Tag Archives: HackSpace magazine

Make an animated sign with Raspberry Pi Pico

Post Syndicated from Andrew Gregory original https://www.raspberrypi.org/blog/make-an-animated-sign-with-raspberry-pi-pico/

Light up your living room like Piccadilly Circus with this Raspberry Pi Pico project from the latest issue of HackSpace magazine. Don’t forget, it’s not too late to get your hands on our new microcontroller for FREE if you subscribe to HackSpace magazine.

HUB75 LED panels provide an affordable way to add graphical output to your projects. They were originally designed for large advertising displays (such as the ones made famous by Piccadilly Circus in London, and Times Square in New York). However, we can use a little chunk of these bright lights in our projects. They’re often given a ‘P’ value, such as P3 or P5 for the number of millimetres between the different RGB LEDs. These don’t affect the working or wiring in any way.

We used a 32×32 Adafruit screen. Other screens of this size may work, or may be wired differently. It should be possible to get screens of different sizes working, but you’ll have to dig through the code a little more to get it running properly.

The most cost- effective way to add 1024 RGB LEDs to your project
The most cost- effective way to add 1024 RGB LEDs to your project

The protocol for running these displays involves throwing large amounts of data down six different data lines. This lets you light up one portion of the display. You then switch to a different portion of the display and throw the data down the data lines again. When you’re not actively writing to a particular segment of the display, those LEDs are off.

There’s no in-built control over the brightness levels – each LED is either on or off. You can add some control over brightness by flicking pixels on and off for different amounts of time, but you have to manage this yourself. We won’t get into that in this tutorial, but if you’d like to investigate this, take a look at the box on ‘Going Further’.

The code for this is on GitHub (hsmag.cc/Hub75). If you spot a way of improving it, send us a pull request
The code for this is on GitHub. If you spot a way of improving it, send us a pull request

The first thing you need to do is wire up the screen. There are 16 connectors, and there are three different types of data sent – colour values, address values, and control values. You can wire this up in different ways, but we just used header wires to connect between a cable and a breadboard. See here for details of the connections.

These screens can draw a lot of power, so it’s best not to power them from your Pico’s 5V output. Instead, use a separate 5V supply which can output enough current. A 1A supply should be more than enough for this example. If you’re changing it, start with a small number of pixels lit up and use a multimeter to read the current.

With it wired up, the first thing to do is grab the code and run it. If everything’s working correctly, you should see the word Pico bounce up and down on the screen. It is a little sensitive to the wiring, so if you see some flickering, make sure that the wires are properly seated. You may want to just display the word ‘Pico’. If so, congratulations, you’re finished!

However, let’s take a look at how to customise the display. The first things you’ll need to adapt if you want to display different data are the text functions – there’s one of these for each letter in Pico. For example, the following draws a lower-case ‘i’:

def i_draw(init_x, init_y, r, g, b):
    for i in range(4):
        light_xy(init_x, init_y+i+2, r, g, b)
    light_xy(init_x, init_y, r, g, b)

As you can see, this uses the light_xy method to set a particular pixel a particular colour (r, g, and b can all be 0 or 1). You’ll also need your own draw method. The current one is as follows:

def draw_text():
    global text_y
    global direction
    global writing
    global current_rows
    global rows

    writing = True
    text_y = text_y + direction
    if text_y > 20: direction = -1
    if text_y < 5: direction = 1
    rows = [0]*num_rows
    #fill with black
    for j in range(num_rows):
    rows[j] = [0]*blocks_per_row

    p_draw(3, text_y-4, 1, 1, 1)
    i_draw(9, text_y, 1, 1, 0)
    c_draw(11, text_y, 0, 1, 1)
    o_draw(16, text_y, 1, 0, 1)
    writing = False

This sets the writing global variable to stop it drawing this frame if it’s still being updated, and then just scrolls the text_y variable between 5 and 20 to bounce the text up and down in the middle of the screen.

This method runs on the second core of Pico, so it can still throw out data constantly from the main processing core without it slowing down to draw images.

Get HackSpace magazine – Issue 40

Each month, HackSpace magazine brings you the best projects, tips, tricks and tutorials from the makersphere. You can get it from the Raspberry Pi Press online store, The Raspberry Pi store in Cambridge, or your local newsagents.

Each issue is free to download from the HackSpace magazine website.

When you subscribe, we’ll send you a Raspberry Pi Pico for FREE.

A banner with the words "Be a Pi Day donor today"

The post Make an animated sign with Raspberry Pi Pico appeared first on Raspberry Pi.

NeoPixel dithering with Pico

Post Syndicated from Ben Everard original https://www.raspberrypi.org/blog/neopixel-dithering-with-pico/

In the extra special Raspberry Pi Pico launch issue of HackSpace magazine, editor Ben Everard shows you how to get extra levels of brightness out of your LEDs with our new board.

WS2812B LEDs, commonly known as NeoPixels, are cheap and widely available LEDs. They have red, green, and blue LEDs in a single package with a microcontroller that lets you control a whole string of them using just one pin on your microcontroller.

The three connections may be in a different order on your LED strip, so check the labels to make sure they’re connected correctly
The three connections may be in a different order on your LED strip, so check the labels to make sure they’re connected correctly

However, they do have a couple of disadvantages:

1) The protocol needed to control them is timing-dependent and often has to be bit-banged.

2) Each colour has 8 bits, so has 255 levels of brightness. However, these aren’t gamma-corrected, so the low levels of brightness have large steps between them. For small projects, we often find ourselves only using the lower levels of brightness, so often only have 10 or 20 usable levels of brightness.

There will usually be wires already connected to your strip, but if you cut it, you’ll need to solder new wires on
There will usually be wires already connected to your strip, but if you cut it, you’ll need to solder new wires on

We’re going to look at how two features of Pico help solve these problems. Firstly, Programmable I/O (PIO) lets us implement the control protocol on a state machine rather than the main processing cores. This means that we don’t have to dedicate any processor time to sending the data out. Secondly, having two cores means we can use one of the processing cores to dither the NeoPixels. This means shift them rapidly between different brightness levels to make pseudo-levels of brightness.

For example, if we wanted a brightness level halfway between levels 3 and 4, we’d flick the brightness back and forth between 3 and 4. If we can do this fast enough, our eyes blur this into a single brightness level and we don’t see the flicker. By varying the amount of time at levels 3 and 4, we can make many virtual levels of brightness. While one core is doing this, we still have a processing core completely free to manipulate the data we want to display.

First, we’ll need a PIO program to communicate with the WS2812B LEDs. The Pico development team have provided an example PIO program to work with – you can see the full details here, but we’ll cover the essentials here. The PIO code is:

.program ws2812
.side_set 1
.define public T1 2
.define public T2 5
.define public T3 3
bitloop:
 out x, 1 side 0 [T3 - 1]
 jmp !x do_zero side 1 [T1 - 1]
 do_one:
 jmp bitloop side 1 [T2 - 1]
 do_zero:
 nop side 0 [T2 - 1]

We looked at the PIO syntax in the main cover feature, but it’s basically an assembly language for the PIO state machine. The WS2812B protocol uses pulses at a rate of 800kHz, but the length of the pulse determines if a 1 or a 0 is being sent. This code uses jumps to move through the loop to set the timings depending on whether the bit (stored in the register x) is 0 or 1. The T1, T2, and T3 variables hold the timings, so are used to calculate the delays (with 1 taken off as the instruction itself takes one clock cycle). There’s also a section in the pio file that links the PIO code and the C code:

% c-sdk {
#include "hardware/clocks.h"
static inline void ws2812_program_init(PIO pio,
uint sm, uint offset, uint pin, float freq, bool
rgbw) {
 pio_gpio_select(pio, pin);
 pio_sm_set_consecutive_pindirs(pio, sm, pin, 1,
true);
 pio_sm_config c = ws2812_program_get_default_
config(offset);
 sm_config_set_sideset_pins(&c, pin);
 sm_config_set_out_shift(&c, false, true, rgbw ?
32 : 24);
 sm_config_set_fifo_join(&c, PIO_FIFO_JOIN_TX);
 int cycles_per_bit = ws2812_T1 + ws2812_T2 +
ws2812_T3;
 float div = clock_get_hz(clk_sys) / (freq *
cycles_per_bit);
 sm_config_set_clkdiv(&c, div);
 pio_sm_init(pio, sm, offset, &c);
 pio_sm_set_enable(pio, sm, true);
}
%}

Most of this is setting the various PIO options – the full range is detailed in the Raspberry Pi Pico C/C++ SDK document.

 sm_config_set_out_shift(&c, false, true, rgbw ? 32
: 24);

This line sets up the output shift register which holds each 32 bits of data before it’s moved bit by bit into the PIO state machine. The parameters are the config (that we’re setting up and will use to initialise the state machine); a Boolean value for shifting right or left (false being left); and a Boolean value for autopull which we have set to true. This means that whenever the output shift register falls below a certain threshold (set in the next parameter), the PIO will automatically pull in the next 32 bits of data.

Using a text editor with programmer’s features such as syntax highlighting will make the job a lot easier
Using a text editor with programmer’s features such as syntax highlighting will make the job a lot easier

The final parameter is set using the expression rgbw ? 32 : 24. This means that if the variable rgbw is true, the value 32 is passed, otherwise 24 is passed. The rbgw variable is passed into this function when we create the PIO program from our C program and is used to specify whether we’re using an LED strip with four LEDs in each (using one red, one green, one blue, and one white) or three (red, green, and blue).

The PIO hardware works on 32-bit words, so each chunk of data we write with the values we want to send to the LEDs has to be 32 bits long. However, if we’re using RGB LED strips, we actually want to work in 24-bit lengths. By setting autopull to 24, we still pull in 32 bits each time, but once 24 bits have been read, another 32 bits are pulled in which overwrite the remaining 8 bits.

sm_config_set_fifo_join(&c, PIO_FIFO_JOIN_TX);

Each state machine has two four-word FIFOs attached to it. These can be used for one going in and one coming out. However, as we only have data going into our state machine, we can join them together to form a single eight-word FIFO using the above line. This gives us a small buffer of time to write data to in order to avoid the state machine running out of data and execution stalling. The following three lines are used to set the speed the state machine runs at:

int cycles_per_bit = ws2812_T1 + ws2812_T2 +
ws2812_T3;
 float div = clock_get_hz(clk_sys) / (freq *
cycles_per_bit);
 sm_config_clkdiv(&c, div);

The WS2812B protocol demands that data is sent out at a rate of 800kHz. However, each bit of data requires a number of state machine cycles. In this case, they’re defined in the variables T1, T2, and T3. If you look back at the original PIO program, you’ll see that these are used in the delays (always with 1 taken off the value because the initial instruction takes one cycle before the delay kicks in). Every loop of the PIO program will take T1 + T2 + T3 cycles. We use these values to calculate the speed we want the state machine to run at, and from there we can work out the divider we need to slow the system clock down to the right speed for the state machine. The final two lines just initialise and enable the state machine.

The main processor

That’s the code that’s running on the state machine, so let’s now look at the code that’s running on our main processor cores. The full code is on github. Let’s first look at the code running on the second core (we’ll look at how to start this code running shortly), as this controls the light levels of the LEDs.

static inline void put_pixel(uint32_t pixel_grb) {
 pio_sm_put_blocking(pio0, 0, pixel_grb << 8u);
}
static inline uint32_t urgb_u32(uint8_t r, uint8_t
g, uint8_t b) {
 return
 ((uint32_t) (r) << 8) |
 ((uint32_t) (g) << 16) |
 (uint32_t) (b);
}
void ws2812b_core() {
int valuer, valueg, valueb;
int shift = bit_depth-8;
 while (1){

for(int i=0; i<STRING_LEN; i++) {
valueb=(pixelsb[i] + errorsb[i]) >> shift;
valuer=(pixelsr[i] + errorsr[i]) >> shift;
valueg=(pixelsg[i] + errorsg[i]) >> shift;
put_pixel(urgb_u32(valuer, valueg, valueb));
errorsb[i] = (pixelsb[i] + errorsb[i]) -
(valueb << shift);
errorsr[i] = (pixelsr[i] + errorsr[i]) -
(valuer << shift);
errorsg[i] = (pixelsg[i] + errorsg[i]) -
(valueg << shift);
 }
sleep_us(400);
}
}

We start by defining a virtual bit depth. This is how many bits per pixel you can use. Our code will then attempt to create the necessary additional brightness levels. It will run as fast as it can drive the LED strip, but if you try to do too many brightness levels, you’ll start to notice flickering.

We found twelve to be about the best with strings up to around 100 LEDs, but you can experiment with others. Our code works with two arrays – pixels which holds the values that we want to display, and errors which holds the error in what we’ve displayed so far (there are three of each for the different colour channels).

If you just want to see this in action, you can download the UF2 file from hsmag.cc/orfgBD and flash it straight to your Pico
If you just want to see this in action, you can download the UF2 file from hsmag.cc/orfgBD and flash it straight to your Pico

To explain that latter point, let’s take a look at the algorithm for determining how to light the LED. We borrowed this from the source code of Fadecandy by Micah Scott, but it’s a well-used algorithm for calculating error rates. We have an outer while loop that just keeps pushing out data to the LEDs as fast as possible. We don’t care about precise timings and just want as much speed as possible. We then go through each pixel.

The corresponding item in the errors array holds the cumulative amount our LED has been underlit so far compared to what we want it to be. Initially, this will be zero, but with each loop (if there’s a difference between what we want to light the LED and what we can light the LED) this error value will increase. These two numbers (the closest light level and the error) added together give the brightness at the pseudo-level, so we need to bit-shift this by the difference between our virtual level and the 8-bit brightness levels that are available.

This gives us the value for this pixel which we write out. We then need to calculate the new error level. Let’s take a look at what this means in practice. Suppose we want a brightness level halfway between 1 and 2 in the 8-bit levels. To simplify things, we’ll use nine virtual bits. 1 and 2 in 8-bit is 2 and 4 in 9 bits (adding an extra 0 to the end multiplies everything by a power of 2), so halfway between these two is a 9-bit value of 3 (or 11 in binary, which we’ll use from now on).

In the first iteration of our loop, pixels is 11, errors is 0, and shift is 1.

value = 11 >> 1 = 1
errors = 11 – 10 = 1

So this time, the brightness level of 1 is written out. The second iteration, we have:

value = 100 >> 1 = 10
errors = 100 – 100 = 0

So this time, the brightness level of 10 (in binary, or 2 in base 10) is written out. This time, the errors go back to 0, so we’re in the same position as at the start of the first loop. In this case, the LED will flick between the two brightness levels each loop so you’ll have a brightness half way between the two.

Using this simple algorithm, we can experiment with different virtual bit-depths. The algorithm will always handle the calculations for us, but we just have to see what creates the most pleasing visual effect for the eye. The larger the virtual bit depth, the more potential iterations you have to go through before the error accumulates enough to create a correction, so the more likely you are to see flicker. The biggest blocker to increasing the virtual bit depth is the sleep_us(400). This is needed to reset the LED strip.

NeoPixels come in many different shapes and sizes

Essentially, we throw out bits at 800kHz, and each block of 24 bits is sent, in turn, to the next LED. However, once there’s a long enough pause, everything resets and it goes back to the first LED. How big that pause is can vary. The truth is that a huge proportion of WS2812B LEDs are clones rather than official parts – and even for official parts, the length of the pause needed to reset has changed over the years.

400 microseconds is conservative and should work, but you may be able to get away with less (possibly even as low as 50 microseconds for some LEDs). The urgb_u32 method simply amalgamates the red, blue, and green values into a single 32-bit string (well, a 24-bit string that’s held inside a 32-bit string), and put_pixel sends this to the state machine. The bit shift there is to make sure the data is in the right place so the state machine reads the correct 24 bits from the output shift register.

Getting it running

We’ve now dealt with all the mechanics of the code. The only bit left is to stitch it all together.

int main() {
 PIO pio = pio0;
 int sm = 0;
 uint offset = pio_add_program(pio, &ws2812_
program);
 ws2812_program_init(pio, sm, offset, PIN_TX,
1000000, false);
 multicore_launch_core1(ws2812b_core);

 while (1) {
 for (int i = 0; i < 30; ++i) {
pixels[i] = i;

for (int j=0;j<30;++j){
 pixels[0] = j;
 if(j%8 == 0) { pixels[1] = j; }
 sleep_ms(50);
 }
 for (int j=30;j>0;--j){
 pixels[0] = j;
 if(j%8 == 0) { pixels[1] = j; }
 sleep_ms(50);
 }
 }
 } }

The method ws2812_program_init calls the method created in the PIO program to set everything up. To launch the algorithm creating the virtual bit-depth, we just have to use multicore_launch_core1 to set a function running on the other core. Once that’s done, whatever we put in the pixels array will be reflected as accurately as possible in the WS2812B LEDs. In this case, we simply fade it in and out, but you could do any animation you like.

Get a free Raspberry Pi Pico

Would you like a free Raspberry Pi Pico? Subscribe to HackSpace magazine via your preferred option here, and you’ll receive your new microcontroller in the mail before the next issue arrives.

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Gifts that last all year round

Post Syndicated from Ashley Whittaker original https://www.raspberrypi.org/blog/gifts-that-last-all-year-round/

What if you could give the joy of opening a Raspberry Pi–themed gift every single month for a whole year? But what if the thought of wrapping 12 individual things fills you with Scrooge-level dread?

Snap up a magazine subscription for one of your nearest and/or dearest and we’ll take care of the packaging and delivery while you sit back and reap all the credit!

You could end up with a few extra gifts depending on what you sign up for so, read on and take your pick.

The MagPi magazine

Magpi magazines fanned out with free gift to the side of them

The official Raspberry Pi magazine comes with a free Raspberry Pi Zero W kit worth £20 when you sign up for a 12-month subscription. You can use our tiniest computer in tonnes of projects, meaning Raspberry Pi fans can never have enough. That’s a top gift-giving bonus for you right there.

Every issue of The MagPi is packed with computing and electronics tutorials, how-to guides, and the latest news and reviews. They also hit their 100th issue this month so, if someone on your list has been thinking about getting a subscription, now is a great time.

Check out subscription deals on the official Raspberry Pi Press store.

HackSpace magazine

Hackspace magazines fanned out with adafruit gift on top

HackSpace magazine is the one to choose for fixers and tinkerers of all abilities. If you’re looking for a gift for someone who is always taking things apart and hacking everyday objects, HackSpace magazine will provide a year of inspiration for them.

12-month subscriptions come with a free Adafruit Circuit Playground Express, which has been specially developed to teach programming novices from scratch and is worth £25.

Check out subscription deals on the official Raspberry Pi Press store.

Custom PC

Some Custom PC magazines fanned out with the free giveaway mouse on top of them

Custom PC is the magazine for people who are passionate about PC technology and hardware. And they’ve just launched a pretty cool new giveaway with every 12-month subscription: a free Chillblast Aero RGB Gaming mouse worth £40. Look, it lights up, it’s cool.

Check out subscription offers on the official Raspberry Pi Press store.

Wireframe magazine

Wireframe magazine lifts the lid on video games. In every issue, you’ll find out how games are made, who makes them, and how you can code them to play for yourself using detailed guides.

The latest deal gets you three issues for just £10, plus your choice of one of our official books as a gift. By the way, that ‘three for £10 plus a free book’ is available across ALL our magazines. Did I not tell you that before? My bad. It’s good though, right?

Check out more subscriptions deals on the official Raspberry Pi Press store.

Three books for the price of one

A selection of Raspberry Pi books on a table surrounded by Christmas decorations

And as an extra Christmas gift to you all, we’ve decided to keep our Black Friday deal rolling until Christmas Eve, so if you buy just one teeny tiny book from the Raspberry Pi Press store, you get two more completely FREE!

Better still, all of the books in the deal only cost £7 or £10 to start with, so makes for a good chunky batch of presents at a brilliantly affordable price.

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Read RFID and NFC tokens with Raspberry Pi | HackSpace 37

Post Syndicated from Andrew Gregory original https://www.raspberrypi.org/blog/read-rfid-and-nfc-tokens-with-raspberry-pi-hackspace-37/

Add a bit of security to your project or make things selectable
by using different cards. In the latest issue of HackSpace magazine, PJ Evans goes contactless.

The HAT is not hard on resources, so you can use many variants of Raspberry Pi

NFC (near-field communication) is based on the RFID (radio-frequency identification) standard. Both allow a device to receive data from a passive token or tag (meaning it doesn’t require external power to work). RFID supports a simple ID message that shouts ‘I exist’, whereas NFC allows for both reading and writing of data.

Most people come into contact with these systems every day, whether it’s using contactless payment, or a card to unlock a hotel or office door. In this tutorial we’ll look at the Waveshare NFC HAT, an add-on for Raspberry Pi computers that allows you to interact with NFC and RFID tokens.

Prepare your Raspberry Pi

We start with the usual step of preparing a Raspberry Pi model for the job. Reading RFID tags is not strenuous work for our diminutive friend, so you can use pretty much any variant of the Raspberry Pi range you like, so long as it has the 40-pin GPIO. We only need Raspberry Pi OS Lite (Buster) for this tutorial; however, you can install any version you wish. Make sure you’ve configured it how you want, have a network connection, and have updated everything by running sudo apt -y update && sudo apt -y upgrade on the command line.

Enable the serial interface

This NFC HAT is capable of communicating over three different interfaces: I2C, SPI, and UART. We’re going with UART as it’s the simplest to demonstrate, but you may wish to use the others. Start by running sudo raspi-config, going to ‘Interfacing options’, and selecting ‘Serial Interface’. When asked if you want to log into the console, say ‘No’. Then, when asked if you want to enable the serial interface, say ‘Yes’. You’ll need to reboot now. This will allow the HAT to talk to our Raspberry Pi over the serial interface.

Configure and install the HAT

As mentioned in the previous step, we have a choice of interfaces and swapping between them means changing some physical settings on the NFC HAT itself. Do not do this while the HAT is powered up in any way. Our HAT can be configured for UART/Serial by default but do check on the wiki at hsmag.cc/iHj1XA. The jumpers at I1 and I0 should both be shorting ‘L’, D16 and D20 should be shorted and on the DIP switch, everything should be off except RX and TX. Check, double-check, attach the HAT to the GPIO, and boot up.

The Waveshare HAT contains many settings. Make sure to read the instructions!

Download the examples

You can download some examples directly from Waveshare. First, we need to install some dependencies. Run the following at the command line:
sudo apt install rpi.gpio p7zip-full python3-pip
pip3 install spidev pyserial

Now, download the files and unpack them:
cd
wget https://www.waveshare.com/w/upload/6/67/Pn532-nfc-hat-code.7z
7z x Pn532-nfc-hat-code.7z

Before you try anything out, you need to edit the example file so that we use UART (see the accompanying code listing).
cd ~/raspberrypi/python
nano example_get_uid.py

Find the three lines that start pn532 = and add a # to the top one (to comment it out). Now remove the # from the line starting pn532 = PN532_UART. Save, and exit.

Try it out!

Finally, we get to the fun part. Start the example code as follows:
python3 example_get_uid.py
If all is well, the connection to the HAT will be announced. You can now place your RFID token over the area of the HAT marked ‘NFC’. Hexadecimal numbers will start scrolling up the screen; your token has been detected! Each RFID token has a unique number, so it can be used to uniquely identify someone. However, this HAT is capable of much more than that as it also supports NFC and can communicate with common standards like MIFARE Classic, which allows for 1kB of storage on the card. Check out example_dump_mifare.py in the same directory (but make sure you make the same edits as above to use the serial connection).

Going further

You can now read unique identifiers on RFID and NFC tokens. As we just mentioned, if you’re using the MIFARE or NTAG2 standards, you can also write data back to the card. The examples folder contains some C programs that let you do just that. The ability to read and write small amounts of data onto cards can lead to some fun projects. At the Electromagnetic Field festival in 2018, an entire game was based around finding physical locations and registering your presence with a MIFARE card. Even more is possible with smartphones, where NFC can be used to exchange data in any form.

Get HackSpace magazine 37 – Out Now!

Each month, HackSpace magazine brings you the best projects, tips, tricks and tutorials from the makersphere. You can get it from the Raspberry Pi Press online store, The Raspberry Pi store in Cambridge, or your local newsagents.

Each issue is free to download from the HackSpace magazine website.

The post Read RFID and NFC tokens with Raspberry Pi | HackSpace 37 appeared first on Raspberry Pi.

Build an arcade cabinet | Hackspace 35

Post Syndicated from Ben Everard original https://www.raspberrypi.org/blog/build-an-arcade-cabinet-hackspace-35/

Games consoles might be fast and have great graphics, but they’re no match for the entertainment value of a proper arcade machine. In this month’s issue of Hackspace magazine, you’re invited to relive your misspent youth with this huge build project.

There’s something special about the comforting solidity of a coin-eating video game monolith, and nothing screams retro fun like a full-sized arcade cabinet sitting in the corner of the room. Classic arcade machines can be a serious investment. Costing thousands of pounds and weighing about the same as a giant panda, they’re out of reach for all but the serious collector. Thankfully, you can recreate that retro experience using modern components for a fraction of the price and weight.

An arcade cabinet is much easier to make than you might expect. It’s essentially a fancy cupboard that holds a monitor, speakers, a computer, a keyboard, and some buttons. You can make your own cabinet using not much more than a couple of sheets of MDF, some clear plastic, and a few cans of spray paint.

If you want a really authentic-looking cabinet, you can find plenty of plans and patterns online. However, most classic cabinets are a bit bigger than you might remember, occupying almost a square metre of floor space. If you scale that down to approximately 60 cm2, you can make an authentic-looking home arcade cabinet that won’t take over the entire room, and can be cut from just two pieces of 8 × 4 (2440 mm × 1220 mm) MDF. You can download our plans, but these are rough plans designed for you to tweak into your own creation. A sheet of 18 mm MDF is ideal for making the body of the cabinet, and 12 mm MDF works well to fill in the front and back panels. You can use thinner sheets of wood to make a lighter cabinet, but you might find it less sturdy and more difficult to screw into.

The sides of the machine should be cut from 18 mm MDF, and will be 6 feet high. The sides need to be as close to identical as possible, so mark out the pattern for the side on one piece of 18 mm MDF, and screw the boards together to hold them while you cut. You can avoid marking the sides by placing the screws through the waste areas of the MDF. Keep these offcuts to make internal supports or brackets. You can cut the rest of the pieces of MDF using the project plans as a guide. 

Why not add a coin machine for extra authenticity

Attach the side pieces to the base, so that the sides hang lower than the base by an inch or two. If you’re more accomplished at woodworking and want to make the strongest cabinet possible, you can use a router to joint and glue the pieces of wood together. This will make the cabinet very slightly narrower and will affect some measurements, but if you follow the old adage to measure twice and cut once, you should be fine. If you don’t want to do this, you can use large angle brackets and screws to hold everything together. The cabinet will still be strong, and you’ll have the added advantage that you can disassemble it in the future if necessary.

Keep attaching the 18 mm MDF pieces, starting with the top piece and the rear brace. Once you have these pieces attached, the cabinet should be sturdy enough to start adding the thinner panels. Insetting the panels by about an inch gives the cabinet that retro look, and also hides any design crimes you might have committed while cutting out the side panels.

The absolute sizing of the cabinet isn’t critical unless you’re trying to make an exact copy of an old machine, so don’t feel too constrained by measuring things down to the millimetre. As long as the cabinet is wide enough to accept your monitor, everything else is moveable and can be adjusted to suit your needs.

Make it shiny

You can move onto decoration once the cabinet woodwork is fitted together. This is mostly down to personal preference, although it’s wise to think about which parts of the case will be touched more often, and whether your colour choices will cause any problems with screen reflection. Matt black is a popular choice for arcade cabinets because it’s non-reflective and any surface imperfections are less noticeable with a matt paint finish.

Aluminium checker plate is a good way of protecting your cabinet from damage, and it can be cut and shaped easily.

Wallpaper or posters make a great choice for decorating the outside of the cabinet, and they are quick to apply. Just be sure to paste all the way up to the edge, and protect any areas that will be handled regularly with aluminium checker plate or plastic sheet. The edges of MDF sheets can be finished with iron-on worktop edging, or with the chrome detailing tape used on cars. You can buy detailing tape in 12 mm and 18 mm widths, which makes it great for finishing edges. The adhesive tape provided with the chrome edging isn’t always very good, so it’s worth investing in some high-strength, double-sided clear vinyl foam tape.

You’ve made your cabinet, but it’s empty at the moment. You’re going to add a Raspberry Pi, monitor, speakers, and a panel for buttons and joysticks. To find out how, you can read the full article in HackSpace magazine 35.  

Get HackSpace magazine 35 Out Now!

Each month, HackSpace magazine brings you the best projects, tips, tricks and tutorials from the makersphere. You can get it from the Raspberry Pi Press online store, The Raspberry Pi store in Cambridge, or your local newsagents.

Each issue is free to download from the HackSpace magazine website.

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Rotary encoders: Raise a Glitch Storm | Hackspace 34

Post Syndicated from Ben Everard original https://www.raspberrypi.org/blog/rotary-encoders-raise-a-glitch-storm-hackspace-34/

A Glitch Storm is an explosive torrent of musical rhythms and sound, all generated from a single line of code. In theory, you can’t do this with a Raspberry Pi running Python – in this month’s new issue, out now, the HackSpace magazine team lovingly acquired a tutorial from The Mag Pi team to throw theory out the window and show you how.

What is a Glitch Storm

A Glitch Storm is a user-influenceable version of bytebeat music. We love definitions like that here at the Bakery: something you have never heard of is simple a development of something else you have never heard of. Bytebeat music was at the heart of the old Commodore 64 demo scene, a competition to see who could produce the most impressive graphs and music in a very limited number of bytes. This was revived/rediscovered and christened by Viznut, aka Ville-Matias Heikkilä, in 2011. And then JC Ureña of the ‘spherical sound society’ converted the concept into the interactive Glitch Storm.

Figure 1: Schematic for the sound-generating circuit

So what is it?

Most random music generators work on the level of notes; that is, notes are chosen one at a time and then played, like our Fractal Music project in The MagPi #66. However, with bytebeat music, an algorithm generates the actual samples levels that make up the sound. This algorithm performs bitwise operations on a tick variable that increments with each sample. Depending on the algorithm used, this may or may not produce something musically interesting. Often, the samples produced exhibit a fractal structure, which is itself similar on many levels, thus providing both the notes and structure.

Enter the ‘Glitch Storm’

With a Glitch Storm, three user-controlled variables – a, b, and c – can be added to this algorithm, allowing the results to be fine-tuned. In the ‘Algorithms’ box, you can see that the bytebeat algorithms simply run; they all repeat after a certain time, but this time can be long, in the order of hours for some. A Glitch Storm algorithm, on the other hand, contains variables that a user can change in real-time while the sample is playing. This exactly what we can do with rotary encoders, without having the algorithm interrupted by checking the state of them all the time.

Figure 2: Schematic for the control box

What hardware?

In order to produce music like this on the Raspberry Pi, we need some extra hardware to generate the sound samples, and also a bunch of rotary encoders to control things. The samples are produced by using a 12-bit A/D converter connected to one of the SPI ports. The schematic of this is shown in Figure 1. The clock rate for the transfer of data to this can be controlled and provides a simple way of controlling, to some extent, the sample rate of the sound. Figure 2 shows the wiring diagram of the five rotary encoders we used.

Making the hardware

The hardware comes as two parts: the D/A converter and associated audio components. These are built on a board that hangs off Raspberry Pi’s GPIO pins. Also on this board is a socket that carries the wires to the control box. We used an IDC (insulation displacement connector) to connect between the board and the box, as we wanted the D/A connection wires to be as short as possible because they carry a high frequency signal. We used a pentagonal box just for fun, with a control in each corner, but the box shape is not important here.

Figure 3: Front physical layout of the interface board

Construction

The board is built on a 20-row by 24-hole piece of stripboard. Figure 3 and Figure 4 show the physical layout for the front and back of the board. The hole number 5 on row 4 is enlarged to 2.5mm and a new hole is drilled between rows 1 and 2 to accommodate the audio jack socket. A 40-way surface-mount socket connector is soldered to the back of the board, and a 20-way socket is soldered to the front. You could miss this out and wire the 20-way ribbon cable direct to the holes in these positions if you want to economise.

Figure 4: Rear physical layout of the interface board

Further construction notes

Note: as always, the physical layout diagram shows where the wires go, not necessarily the route they will take. Here, we don’t want wires crossing the 20-way connector, so the upper four wires use 30AWG Kynar wire to pop under the connector and out through a track hole, without soldering, on the other side. When putting the 20-way IDC pin connector on the ribbon cable, make sure the red end connector wire is connected to the pin next to the downward-pointing triangle on the pin connector. Figure 5 shows a photograph of the control box wiring

Figure 5: Wiring of the control board

Testing the D/A

The live_byte_beat.py listing on GitHub is a minimal program for trying out a bytebeat algorithm. It will play until stopped by pressing CTRL+C. The variable v holds the value of the sample, which is then transferred to the D/A over SPI in two bytes. The format of these two bytes is shown in Figure 6, along with how we have to manipulate v to achieve an 8-bit or 12-bit sample output. Note that all algorithms were designed for an 8-bit sample size, and using 12 bits is a free bonus here: it does sound radically different, and not always in a good way.

The main software

The main software for this project is on our GitHub page, and contains 24 Pythonised algorithms. The knobs control the user variables as well as the sample rate and what algorithm to use. You can add extra algorithms, but if you are searching online for them, you will find they are written in C. There are two major differences you need to note when converting from C to Python. The first is the ternary operation which in C is a question mark, and the second is the modulus operator with a percent sign. See the notes that accompany the main code about these.

Figure 6: How to program the registers in the D/A converter

Why does this work?

There are a few reasons why you would not expect this to work on a Raspberry Pi in Python. The most obvious being that of the interruptions made by the operating system, regularly interrupting the flow of output samples. Well, it turns out that this is not as bad as you might fear, and the extra ‘noise’ this causes is at a low level and is masked by the glitchy nature of the sound. As Python is an interpreted language, it is just about fast enough to give an adequate sample rate on a Raspberry Pi 4.

Make some noise

You can now explore the wide range of algorithms for generating a Glitch Storm and interact with the sound. On our GitHub page there’s a list of useful links allowing you to explore what others have done so far. For a sneak preview of the bytebeat type of sound, visit magpi.cc/bytebeatdemo; you can even add your own algorithms here. For interaction, however, there’s no substitute for having your own hardware. The best settings are often found by making small adjustments and listening to the long-term effects – some algorithms surprise you about a minute or two into a sequence by changing dramatically.

Get HackSpace magazine issue 34 — out today

HackSpace magazine issue 34: on sale now!

HackSpace magazine is out now, available in print from the Raspberry Pi Press online store, your local newsagents, and the Raspberry Pi Store, Cambridge.

You can also download the directly from PDF from the HackSpace magazine website.

Subscribers to HackSpace for 12 months to get a free Adafruit Circuit Playground, or choose from one of our other subscription offers, including this amazing limited-time offer of three issues and a book for only £10!

If you liked this project, it was first featured in The MagPi Magazine. Download the latest issue for free or subscribe here.

The post Rotary encoders: Raise a Glitch Storm | Hackspace 34 appeared first on Raspberry Pi.

Watch wildlife with a Raspberry Pi nature camera| Hackspace 33

Post Syndicated from Rosie Hattersley original https://www.raspberrypi.org/blog/watch-wildlife-with-a-raspberry-pi-nature-camera-hackspace-33/

The past few months have given us ample opportunity to stare at the creatures that reside outside. In issue 33 of Hackspace Magazine, out today, Rosie Hattersley looks at ways to track them.

It’s been a remarkable spring and early summer, and not just because many of us have had more time than usual to be able to appreciate our surroundings. The weather has been mild, the skies clear, and pollution levels low. As a result, it ought to be a bumper year for plants and wildlife. Unfortunately, the lockdown limited opportunities for embracing unexpectedly good weather while simultaneously making us more aware of the wildlife on our doorsteps.

“It’s a great time to take a fresh look at the world around us”

If you’re the outdoorsy type who likes to get out and stare intently at feathered friends from the comfort of a large shed on the edge of a lagoon, you may have spent the past few months getting to know suburban birds during your exercise walks, rather than ticking off unusual species. As things finally open up, it’s a great time to take a fresh look at the world around us, and some of the projects focused on the creatures we share it with.

Make your own nature cam

Equipped with a Raspberry Pi connected to a camera and USB power bank, we are able to spy on the wildlife in our garden. The Raspberry Pi Camera Module V2 is a good option here (it’s less intrusive than the newer High Quality Camera, though that would make a superb critter-cam). It’s important not to disturb wildlife with lighting, so use an infrared module, such as the NoIR Camera Module, if you want to snap evening or night-time wildlife activity. Connect the Camera Module to the Camera port on Raspberry Pi using the cable provided, then gently pull up the edges of the port’s plastic clip and insert the ribbon cable. Push the clip back into place and the Camera Module will remain attached. Try our ‘Getting started with the Raspberry Pi Camera Module‘.

A Raspberry Pi plus camera is a great solution for web-enabled snapping

Set up your Raspberry Pi and let it perform any OS updates needed. (The Raspberry Pi Imager tool can help)

You’ll need a keyboard and mouse to set up the Raspberry Pi, but you can disconnect them at the end. Insert the updated microSD card and use a regular power supply to start it up (keep your power bank on charge separately while you set things up). Go through the Raspberry Pi setup, making sure you change the default password (since it will be accessible to anyone), and connect to your wireless network. It helps if you can access this network from the garden.

Turn on the interface for the camera, and enable SSH and VNC so you can access Raspberry Pi OS remotely when it’s sitting out in the garden. To do this, open Menu > Preferences > Raspberry Pi Configuration and click on Interface, then set Camera, SSH, and VNC to Enabled (see this documentation). Click Yes when advised that a reboot is needed. 

Next, test the camera. Open a terminal window and enter:

raspistill -o Desktop/image.jpg

A preview window will appear. After a few moments, it will save an image to the Desktop. Double-click the image.jpg file to open it.

You can use Python to take pictures and shoot video. This is handy if you want to create a time-lapse or video camera. This Raspberry Pi Project guide explains how to control the camera with Python.

You can use a USB power bank to run your Raspberry Pi wildlife camera

Note that recording video will quickly fill up your storage space and drain the battery. A better idea is to leave the preview running and use VNC to view the camera remotely. A neater option is to hook up your Raspberry Pi to YouTube (as explained in this Raspberry Pi infrared bird-box project).

Open a web page and go to studio.youtube.com. Sign in, or set up a YouTube account. You will need to enable permission to live-stream. This involves providing YouTube with your phone number. Click Settings, Channel, and ‘Feature eligibility’, expand ‘Features that require phone verification’, and click ‘Verify phone number’. Type in your phone number, then enter the code that YouTube sends you as a text message. For security reasons, it will take 24 hours for YouTube to activate this feature on your account.

Get your key and add to terminal

On the left-hand side of the screen you should see a menu with the My Channel option available:

In the middle of the screen you should see the Video Manager option. On the left you should see a Live Streaming option. Look for and select the ‘Stream now BETA’ option. 

Scroll down to the bottom of the page and you should see the ENCODER SETUP option.

Here there is a Server URL and a Stream name/key. The key is shown as a line of asterisks, until you click the Reveal button. Keep the key secret and don’t share it online. Copy your Stream Key to a text document (password-protect it, ideally).

Open a terminal window and enter this command (replacing <key goes here> with your own key:

raspivid -o - -t 0 -w 1280 -h 720 -fps 25 -b 4000000 -g 50 | ffmpeg -re -ar 44100 -ac 2 -acodec pcm_s16le -f s16le -ac 2 -i /dev/zero -f h264 -i - -vcodec copy -acodec aac -ab 128k -g 50 -strict experimental -f flv rtmp://a.rtmp.youtube.com/live2/<key goes here>

With this running on Raspberry Pi, you can view the stream from your camera on YouTube on any computer. This infrared bird-box project explains more about the command options. 

You’ll want this script to execute on startup. Create a file for your startup script and add the aforementioned raspivid stream command to it:

sudo nano /etc/init.d/superscript

Make the script executable:

sudo chmod 755 /etc/init.d/superscript

And register the script to run at startup:

sudo update-rc.d superscript defaults

You can see details of scripts running at startup here.

Shut down Raspberry Pi and fit the computer and Camera Module inside a case (if you are using one). Position Raspberry Pi in your garden and power it with the USB power bank. It will connect to your wireless network, and run the YouTube streaming key. 

Navigate to your channel on YouTube at any time to see the action taking place in your garden. 

Get HackSpace magazine issue 33 — out today

HackSpace magazine issue 33: on sale now!

HackSpace magazine is out now, available in print from the Raspberry Pi Press online store, your local newsagents, and the Raspberry Pi Store, Cambridge.

You can also download the directly from PDF from the HackSpace magazine website.

Subscribers to HackSpace for 12 months to get a free Adafruit Circuit Playground, or choose from one of our other subscription offers, including this amazing limited-time offer of three issues and a book for only £10!

The post Watch wildlife with a Raspberry Pi nature camera| Hackspace 33 appeared first on Raspberry Pi.

OctoPrint: a baby monitor for your 3D printer

Post Syndicated from Andrew Gregory original https://www.raspberrypi.org/blog/octoprint-a-baby-monitor-for-your-3d-printer/

In issue 32 of HackSpace magazine, out now, we talk to Gina Häußge, creator of OctoPrint – it sits on a Raspberry pi and monitors your 3D printer.

Gina Häußge, creator and maintainer of OctoPrint

There’s something enchanting about watching a 3D printer lay down hot plastic. Seeing an object take shape before your eyes is utterly compelling, which is perhaps why we love watching 3D printing time-lapse videos so much.

Despite this, it would be impractical and inefficient to sit and watch every time you sent a print job through. That’s why we should all be grateful for OctoPrint. This free, open-source software monitors your 3D printer for you, keeping you from wasting plastic and ensuring that you can go about your business without fearing for your latest build.
OctoPrint is the creation of Gina Haüßge. We enjoyed a socially distant chat with her about the challenges of running an open-source project, making, and what it’s like to have a small project become huge.

HackSpace: Most people who have used a 3D printer will have heard of OctoPrint, but for the benefit of those who haven’t, what is it?

Gina Haüßge: Somebody once called it a baby monitor for your 3D printer. I really like this description. It’s pretty much a combination of a baby monitor and a remote control, because it allows you to go through any web browser on your network and monitor what your printer is currently up to, how much the current job has progressed. If you have a webcam set up, it can show you the print itself, so you can see that everything is working correctly, it’s still on the bed, and all that.

It also offers a plug-in interface so that it can be expanded with various features and functionality, and people have written a ton of integrations with notification systems. And all of this runs on pretty much any system that runs Python. I have to say Python, not MicroPython, the full version. Usually Linux, and the most common use case is to run it on a Raspberry Pi, and this is also how I originally set it out to work.

Most people think it only runs on a Raspberry Pi, but no. It will run on any old laptop that you still have lying around. It’s cross-platform, so you don’t need to buy a Raspberry Pi if you have another machine that will fit the bill.

OctoPrint is most commonly run on a Raspberry Pi

HS: How long have you been working on it?

GH: I originally sat down to write it over my Christmas break in 2012, because I had got my first 3D printer back then. It was sitting in my office producing fumes and noise for hours on end, which was annoying when trying to work, or game, or anything else.

I thought there must be a solution involving attaching one of these nifty new Raspberry Pis that had just come out. Someone must have written something, right? I browsed around the internet, realised that the closest thing to what I was looking for treated the printer as a black box – to fire job data at it and hope that it gets it right. That was not what I wanted; I wanted this feedback channel. I wanted to see what was happening; I wanted to monitor the temperatures; I wanted to monitor the job progress.

The very first version back then was a plug-in for Cura, before Cura even supported plug-ins. After my Christmas break, I went, OK, it’s doing everything I wanted it to do; back to work at my normal regular job. And then it exploded. I started getting emails, issue reports, and feature requests from all over the world. ‘Can you make it also do this?’ ‘Hey, I have this other printer with this slightly different firmware that behaves like this; can you adapt it so that it works with this?’. ‘Can you remove it from Cura, and have it so it works standalone?’ Suddenly I had this huge open-source project on my hands. I didn’t do any kind of promotion for it or anything like that. I just posted about it in a Google+ community, of all things, and from there it grew by word of mouth.

A year or so later, I reduced my regular job to 80%, to have one day a week for OctoPrint, but that didn’t suffice either with everything that was going on. Then I had the opportunity to go full-time, sponsored by a single company who also made 3D printers, and they ran out of money in 2016. That was when I turned to crowdfunding, which has been the mode of operation ever since. Around 95% of everything that is done on OctoPrint is run by me, and I work on it full-time now. Since 2014.

A lot of the stuff that I have been adding over the years, for instance, the plug-in system itself, would not have been possible as a pet side project, not with a day job.

HS: What are you working on at the moment?

GH: In March just gone, I released the next big version, to make OctoPrint Python 3-compatible, because at the start of the year Python was deemed end of life, so I had to do something. The problem is that there’s a flourishing plug-in ecosystem written in Python 2, so for now, I’m stuck with having to support both, and trying to motivate the plug-in maintainers to also migrate, which is a ton of fun actually. I wrote a migration guide, tracking in the plug-in repository how many plugs are compatible. Newly registered plug-ins have to be compatible too.

HS: Do you have any idea how many people use OctoPrint?

GH: Nine months, a year ago, I introduced usage tracking. It’s my own bundled plug-in that ships with OctoPrint that does anonymous user tracking through my own platform, so no GDPR issues should arise there. And what this shows me is that, over the course of the last seven days, I saw 66,000 instances, and the last 30 days, I saw 91,000 instances.

But that’s only those who have opted into the usage tracking, which obviously is only a fraction. I have no idea about the fraction – whether the real number is five times, ten times higher, I’ve no way of knowing.

When I did the most recent big update, I got some statistics back from piwheels [a Python package repository]. They saw a spike in repositories that were being pulled from their index, which corresponded to dependencies that the new version of OctoPrint depends on, and the spike that they saw corresponded with the day that I rolled out the new version. Based on that, it looks like there’s probably ten times as many instances out there. I didn’t expect that. So the total number of users could be 700,000, it could be over a million, I have no idea. But based on these piwheels stats, it’s in that ballpark.

HS: And are you seeing a growth in those figures?

GH: Yes. Especially now, with the pandemic going on. If you had asked me three or four months ago, just when the pandemic started, I would have told you more like 60,000 per 30 days. So I saw a significant increase. I also saw a significant usage increase in the last couple of weeks.

I also saw a significant increase in support overheads in the last couple of weeks, which was absolutely insane. It was like everyone and their mother wanted to know something from me, writing me emails, opening tickets and all that, and this influx of people has not stopped yet. At first I thought, well I’ll just go into crunch mode and weather this out, but that didn’t work out. I had to find new ways to cope in order to keep this sustainable.

HS: You can’t have crunch mode for three months!

GH: I mean it’s OK for four weeks or so, but then you start to notice side effects on your own well-being. It’s not a good idea. I’m in for the long haul.

HS: Wanting a feedback channel instead of just firing off commands that work silently makes a lot of sense.

GH: It’s not like a paper printer where you fire and forget, so treating it as a black box, where you don’t get anything back on status and all that, is bound to be trouble. This is a complicated machine where a lot of stuff can go wrong, so it makes sense to have a feedback channel — at least that was my intuition back then, and evidently, a lot of people thought the same.

HS: You must have saved people countless hours and hours of wasted time, filament, and energy.

GH: I’ve also heard that I’ve saved at least one marriage! Someone wrote me an email a couple of years ago thanking me because the person had a new printer in their garage and was constantly monitoring it, sitting in front of it. Apparently the wife and kids were not too thrilled by this. They installed OctoPrint, and since then they’ve been happy again.

Get HackSpace magazine issue 31 — out today

HackSpace magazine issue 32: on sale now!

You can read the rest of HackSpace magazine’s interview with Gina Häußge in issue 32, out today and available online from the Raspberry Pi Press online store. You can also download issue 32 for free.

The post OctoPrint: a baby monitor for your 3D printer appeared first on Raspberry Pi.

Design your own Internet of Things with HackSpace magazine

Post Syndicated from Andrew Gregory original https://www.raspberrypi.org/blog/design-your-own-internet-of-things-with-hackspace-magazine/

In issue 31 of HackSpace magazine, out today, PJ Evans looks at DIY smart homes and homemade Internet of Things devices.

In the last decade, various companies have come up with ‘smart’ versions of almost everything. Microcontrollers have been unceremoniously crowbarred into devices that had absolutely no need for microcontrollers, and often tied to phone apps or web services that are hard to use and don’t work well with other products.

Put bluntly, the commercial world has struggled to deliver an ecosystem of useful smart products. However, the basic principle behind the connected world is good – by connecting together sensors, we can understand our local environment and control it to make our lives better. That could be as simple as making sure the plants are correctly watered, or something far more complex.

The simple fact is that we each lead different lives, and we each want different things out of our smart homes. This is why companies have struggled to create a useful smart home system, but it’s also why we, as makers, are perfectly placed to build our own. Let’s dive in and take a look at one way of doing this – using the TICK Stack – but there are many more, and we’ll explore a few alternatives later on.

Many of our projects create data, sometimes a lot of it. This could be temperature, humidity, light, position, speed, or anything else that we can measure electronically. To be useful, that data needs to be turned into information. A list of numbers doesn’t tell you a lot without careful study, but a line graph based on those numbers can show important information in an instant. Often makers will happily write scripts to produce charts and other types of infographics, but now open-source software allows anyone to log data to a database, generate dashboards of graphs, and even trigger alerts and scripts based on the incoming data. There are several solutions out there, so we’re going to focus on just one: a suite of products from InfluxData collectively known as the TICK Stack.

InfluxDB

The ‘I’ in TICK is the database that stores your precious data. InfluxDB is a time series database. It differs from regular SQL databases as it always indexes based on the time stamp of the incoming data. You can use a regular SQL database if you wish (and we’ll show you how later), but what makes InfluxDB compelling for logging data is not only its simplicity, but also its data-management features and built-in web-based API interface. Getting data into InfluxDB can be as easy as a web post, which places it within the reach of most internet-capable microcontrollers.

Kapacitor

Next up is our ‘K’. Kapacitor is a complex data processing engine that acts on data coming into your InfluxDB. It has several purposes, but the common use is to generate alerts based on data readings. Kapacitor supports a wide range of alert ‘endpoints’, from sending a simple email to alerting notification services like Pushover, or posting a message to the ubiquitous Slack. Multiple alerts to multiple destinations can be configured, and what constitutes an alert status is up to you. More advanced uses of Kapacitor include machine learning and anomaly detection.

Chronograf

The problem with Kapacitor is the configuration. It’s a lot of work with config files and the command line. Thoughtfully, InfluxData has created Chronograf, a graphical user interface to both Kapacitor and InfluxDB. If you prefer to keep away from the command line, you can query and manage your databases here as well as set up alerts, metrics that trigger an alert, and the configurations for the various handlers. This is all presented through a web app that you can access from anywhere on your network. You can also build ‘Dashboards’ – collections of charts displayed on a single page based on your InfluxDB data.

Telegraf

Finally, our ’T’ in TICK. One of the most common uses for time series databases is measuring computer performance. Telegraf provides the link between the machine it is installed on and InfluxDB. After a simple install, Telegraf will start logging all kinds of data about its host machine to your InfluxDB installation. Memory usage, CPU temperatures and load, disk space, and network performance can all be logged to your database and charted using Chronograf. This is more due to the Stack’s more common use for monitoring servers, but it’s still useful for making sure the brains of our network-of-things is working properly. If you get a problem, Kapacitor can not only trigger alerts but also user-defined scripts that may be able to remedy the situation.

Get HackSpace magazine issue 31 — out today

HackSpace magazine issue 31: on sale now!

You can read the rest of HackSpace magazine’s DIY IoT feature in issue 31, out today and available online from the Raspberry Pi Press online store. You can also download issue 31 for free.

The post Design your own Internet of Things with HackSpace magazine appeared first on Raspberry Pi.

Build low-power, clock-controlled devices

Post Syndicated from Andrew Gregory original https://www.raspberrypi.org/blog/build-low-power-clock-controlled-devices/

Do you want to make a sensor with a battery life you can measure in days rather than hours? Even if it contains a (relatively!) power-hungry device like a Raspberry Pi? By cunning use of a real-time clock module, you can make something that wakes up, does its thing, and then goes back to sleep. While asleep, the sensor will sip a tiny amount of current, making it possible to remotely monitor the temperature of your prize marrow in the greenhouse for days on end from a single battery. Read on to find out how to do it.

A sleeping Raspberry Pi Zero apparently consuming no current!

You’ll need:

  • DS3231 powered real-time clock module with battery backup: make sure it has a battery holder and an INT/SQW output pin
  • P-channel MOSFET: the IRF9540N works well
  • Three resistors: 2.2 kΩ, 4.7 kΩ, and 220 Ω
  • A device you want to control: this can be a PIC, Arduino, ESP8266, ESP32, or Raspberry Pi. My software is written in Python and works in MicroPython or on Raspberry Pi, but you can find DS3231 driver software for lots of devices
  • Sensor you want to use: we’re using a BME280 to get air temperature, pressure, and humidity
  • Breadboard or prototype board to build up the circuit

We’ll be using a DS3231 real-time clock which is sold in a module, complete with a battery. The DS3231 contains two alarms and can produce a trigger signal to control a power switch. To keep our software simple, we are going to implement an interval timer, but there is nothing to stop you developing software that turns on your hardware on particular days of the week or days in the month. The DS3231 is controlled using I2C, which means it can be used with lots of devices.

You can pick up one of these modules from lots of suppliers. Make sure that you get one with the SQW connection, as that provides the alarm signal

MOSFET accompli

The power to our Raspberry Pi Zero is controlled via a P-channel MOSFET device operating as a switch. The 3.3 V output from Raspberry Pi is used to power the DS3231 and our BME280 sensor. The gate on the MOSFET is connected via a resistor network to the SQW output from the DS3231.

You can think of a MOSFET as a kind of switch. It has a source pin (where we supply power), a drain pin (which is the output the MOSFET controls), and a gate pin. If we change the voltage on the gate pin, this will control whether the MOSFET conducts or not.

We use a P-channel MOSFET to switch the power because the gate voltage must be pulled down to cause the MOSFET to conduct, and that is how P-channel devices function.

MOSFET devices are all about voltage. Specifically, when the voltage difference between the source and the gate pin reaches a particular value, called the threshold voltage, the MOSFET will turn on. The threshold voltage is expressed as a negative value because the voltage on the gate must be lower than the voltage on the source. The MOSFET that we’re using turns on at a threshold voltage of around -3.7 volts and off at a voltage of -1.75 volts.

The SQW signal from the DS3231 is controlled by a transistor which is acting as a switch connected to ground inside the DS3231. When the alarm is triggered, this transistor is turned on, connecting the SQW pin to ground. The diagram below shows how this works.

The resistors R1 and R2 are linked to the supply voltage at one end and the SQW pin and the MOSFET gate on the other. When SQW is turned off the voltage on the MOSFET gate is pulled high by the resistors, so the MOSFET turns off. When SQW is turned on, it pulls the voltage on the MOSFET gate down, turning it on.

Unfortunately, current leaking through R1 and R2 to the DN3231 means that we are not going to get zero current consumption when the MOSFET is turned off, but it is much less than 1 milliamp.

We’re using a BME280 environmental sensor on this device. It is connected via I2C to Raspberry Pi. You don’t need this sensor to implement the power saving

Power control

Now that we have our hardware built, we can get some code running to control the power. The DS3231 is connected to Raspberry Pi using I2C. Before you start, you must enable I2C on your Raspberry Pi using the raspi-config tool. Use sudo raspi-config and select Interfacing Options. Next, you need to make sure that you have all the I2C libraries installed by issuing this command at a Raspberry Pi console:

sudo apt-get install python3-smbus python3-dev i2c-tools

The sequence of operation of our sensor is as follows:

  1. The program does whatever it needs to do. This is the action that you want to perform at regular intervals. That may be to read a sensor and send the data onto the network, or write it to a local SD card or USB memory key. It could be to read something and update an e-ink display. You can use your imagination here.
  2. The program then sets an alarm in the DS3231 at a point in the future, when it wants the power to come back on.
  3. Finally, the program acknowledges the alarm in the DS3231, causing the SQW alarm output to change state and turn off the power.

Clock setting

The program below only uses a fraction of the capabilities of the DS3231 device. It creates an interval timer that can time hours, minutes, and seconds. Each time the program runs, the clock is set to zero, and the alarm is configured to trigger when the target time is reached.

Put the program into a file called SensorAction.py on your Raspberry Pi, and put the code that you want to run into the section indicated.

import smbus

bus = smbus.SMBus(1)

DS3231 = 0x68

SECONDS_REG = 0x00
ALARM1_SECONDS_REG = 0x07

CONTROL_REG = 0x0E
STATUS_REG = 0x0F

def int_to_bcd(x):
    return int(str(x)[-2:], 0x10)

def write_time_to_clock(pos, hours, minutes, seconds):
    bus.write_byte_data(DS3231, pos, int_to_bcd(seconds))
    bus.write_byte_data(DS3231, pos + 1, int_to_bcd(minutes))
    bus.write_byte_data(DS3231, pos +2, int_to_bcd(hours))

def set_alarm1_mask_bits(bits):
    pos = ALARM1_SECONDS_REG
    for bit in reversed(bits):
        reg = bus.read_byte_data(DS3231, pos)
        if bit:
            reg = reg | 0x80
        else:
            reg = reg & 0x7F
        bus.write_byte_data(DS3231, pos, reg)
        pos = pos + 1

def enable_alarm1():
    reg = bus.read_byte_data(DS3231, CONTROL_REG)
    bus.write_byte_data(DS3231, CONTROL_REG, reg | 0x05)

def clear_alarm1_flag():
    reg = bus.read_byte_data(DS3231, STATUS_REG)
    bus.write_byte_data(DS3231, STATUS_REG, reg & 0xFE)

def check_alarm1_triggered():
    return bus.read_byte_data(DS3231, STATUS_REG) & 0x01 != 0

def set_timer(hours, minutes, seconds):
    # zero the clock
    write_time_to_clock(SECONDS_REG, 0, 0, 0)
    # set the alarm
    write_time_to_clock(ALARM1_SECONDS_REG, hours, minutes, seconds)
    # set the alarm to match hours minutes and seconds
    # need to set some flags
    set_alarm1_mask_bits((True, False, False, False))
    enable_alarm1()
    clear_alarm1_flag()

#
# Your sensor behaviour goes here
#
set_timer(1,30,0)

The set_timer function is called to set the timer and clear the alarm flag. This resets the alarm signal and powers off the sensor. The example above will cause the sensor to shut down for 1 hour 30 minutes.

You can use any other microcontroller that implements I2C

Power down

The SensorAction program turns off your Raspberry Pi without shutting it down properly, which is something your mother probably told you never to do. The good news is that in extensive testing, we’ve not experienced any problems with this. However, if you want to make your Raspberry Pi totally safe in this situation, you should make its file system ‘read-only’, which means that it never changes during operation and therefore can’t be damaged by untimely power cuts. There are some good instructions from Adafruit here: hsmag.cc/UPgJSZ.

Note: making the operating system file store read-only does not prevent you creating a data logging application, but you would have to log the data to an external USB key or SD card and then dismount the storage device before killing the power.

If you are using a different device, such as an ESP8266 or an Arduino, you don’t need to worry about this as the software in them is inherently read-only.

The SQW output from the DS3231 will pull the gate of the MOSFET low to turn on the power to Raspberry Pi

Always running

To get the program to run when the Raspberry Pi boots, use the Nano editor to add a line at the end of the rc.local file that runs your program.

sudo nano /etc/rc.local

Use the line above at the command prompt to start editing the rc.local file and add the following line at the end of the file:

python3 /home/pi/SensorAction.py &

This statement runs Python 3, opens the SensorAction.py file, and runs it. Don’t forget the ampersand (&) at the end of the command: this starts your program as a separate process, allowing the boot to complete. Now, when Raspberry Pi boots up, it will run your program and then shut itself down. You can find a full sample application on the GitHub pages for this project (hsmag.cc/Yx7q6t). It logs air temperature, pressure, and humidity to an MQTT endpoint at regular intervals. Now, go and start tracking that marrow temperature!

Issue 30 of HackSpace magazine is out now

The latest issue of HackSpace magazine is on sale now, and you can get your copy from the Raspberry Pi Press online store. You can also download it for free to check it out first.

UK readers can take advantage of our special subscriptions offer at the moment.

3 issues for £10 & get a free book worth £10…

If you’re in the UK, get your first three issues of HackSpace magazine, The MagPi, Custom PC, or Digital SLR Photography delivered to your door for £10, and choose a free book (itself worth £10) on top!

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Special offer for magazine readers

Post Syndicated from Russell Barnes original https://www.raspberrypi.org/blog/special-offer-for-magazine-readers/

You don’t need me to tell you about the unprecedented situation that the world is facing at the moment. We’re all in the same boat, so I won’t say anything about it other than I hope you stay safe and take care of yourself and your loved ones.

The other thing I will say is that every year, Raspberry Pi Press produces thousands of pages of exciting, entertaining, and often educational content for lovers of computing, technology, games, and photography.

In times of difficulty, it’s not uncommon for people to find solace in their hobbies. The problem you’ll find yourself with is that it’s almost impossible to buy a magazine at the moment, at least in the UK: most of the shops that sell them are closed (and even most of their online stores are too).

We’re a proactive bunch, so we’ve done something about that:


From today, you can subscribe to The MagPi, HackSpace magazine, Custom PC, or Digital SLR Photography at a cost of three issues for £10 in the UK – and we’re giving you a little extra too.

We like to think we produce some of the best-quality magazines on the market today (and you only have to ask our mums if you want a second opinion). In fact, we’d go as far as to say our magazines are exactly the right mix of words and pictures for making the most of all the extra home-time you and your loved ones are having.

Take your pick for three issues at £10 and get a free book worth £10!

If you take us up on this offer, we’ll send the magazines direct to your door in the UK, with free postage. And we’re also adding a gift to thank you for signing up: on top of your magazines, you’ll get to choose a book that’s worth £10 in itself.

In taking up this offer, you’ll get some terrific reading material, and we’ll deliver it all straight to you — no waiting around. You’ll also be actively supporting our print magazines and the charitable work of the Raspberry Pi Foundation.

I hope that among our magazines, you’ll find something that’s of interest to you or, even better yet, something that sparks a new interest. Enjoy your reading!

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Build a physical game controller for Infinite Bunner

Post Syndicated from Andrew Gregory original https://www.raspberrypi.org/blog/build-a-physical-game-controller-for-infinite-bunner/

In HackSpace magazine issue 28 we had a look at how to create an ultrasonic controller for a version of Pong called Boing!. This month, we’re going to take a step further forward through video game history and look at the game Frogger. In this classic game, you control a frog as it makes its way across logs, roads, and train tracks, avoiding falling in the water or getting hit.

Infinite Bunner

The tribute to Frogger in the new Code the Classics Volume 1 book is called Infinite Bunner, and works in much the same way, except you control a bunny.

Jump along the logs, dodge the traffic, avoid the trains, and keep your bunny alive for as long as possible

All this hopping got us thinking about a controller. Our initial idea was that since the animals jump, so should the controller. An accelerometer can detect freefall, so it shouldn’t be too hard to convert that into button presses. However, it turns out that computer-controlled frogs and rabbits can jump much, much faster than humans can, and we really struggled to get a working game mechanic, so we compromised a little and worked with ‘flicks’.

The flick controller

The basic idea is that you tilt the controller left or right to move left or right, but you have to flick it up to register a jump (simply holding it upright won’t work).

We’ve used a Circuit Playground Bluefruit as our hardware, but it would work equally well with a Circuit Playground Express. There are two key parts to the software. The first is reading in accelerometer values and use these to know what orientation the board is in, and the second is the board mimicing a USB keyboard and sending keystrokes to any software running on it.

Playing Infinite Bunner

The first step is to get Infinite Bunner working on your machine.

Get your copy of Code the Classics today

You can download the code for all the Code the Classics Volume 1 games here. Click on Clone or Download > Download ZIP. Unzip the download somewhere.

You’ll need Python 3 with Pygame Zero installed. The process for this differs a little between different computers, but there’s a good overview of all the different options on page 186 of Code the Classics.

Subscribe to HackSpace magazine for twelve months and you get a Circuit Playground Express for free! Then you can make your very own Infinite Bunner controller

Once everything’s set up, open a terminal and navigate to the directory you unzipped the code in. Then, inside that, you should find a folder called bunner-master and move into that. You can then run:

python3 bunner.py

Have a few goes playing the game, and you’ll find that you need the left, right, and up arrow keys to play (there is also the down arrow, but we’ve ignored this since we’ve never actually used it in gameplay – if you’re a Frogger/Bunner aficionado, you may wish to implement this as well).

Reading the accelerometer is as easy as importing the appropriate module and running one line:

from adafruit_circuitplayground import cpx, y, z = cp.acceleration

Sending key presses is similarly easy. You can set up a keyboard with the following:

from adafruit_hid.keyboard import Keyboard
from adafruit_hid.keyboard_layout_us import KeyboardLayoutUS
from adafruit_hid.keycode import Keycode

keyboard = Keyboard(usb_hid.devices)

Then send key presses with code such as this:

time.keyboard.press(Keycode.LEFT_ARROW) time.sleep(0.1)
keyboard.release_all()

The only thing left is to slot in our mechanics. The X-axis on the accelerometer can determine if the controller is tilted left or right. The output is between 10 (all the way left) and -10 (all the way right). We chose to threshold it at 7 and -7 to require the user to tilt it most of the way. There’s a little bit of fuzz in the readings, especially as the user flicks the controller up, so having a high threshold helps avoid erroneous readings.

The Y-axis is for jumping. In this case, we require a ‘flap’ where the user first lifts it up (over a threshold of 5), then back down again.

The full code for our controller is:

import time
from adafruit_circuitplayground import cp
import usb_hid
from adafruit_hid.keyboard import Keyboard
from adafruit_hid.keyboard_layout_us import KeyboardLayoutUS
from adafruit_hid.keycode import Keycode

keyboard = Keyboard(usb_hid.devices)

jumping = 0
up=False
while True:
    x, y, z = cp.acceleration
    if abs(y) > 5:
        up=True
    if y < 5 and up:
        keyboard.press(Keycode.UP_ARROW)
        time.sleep(0.3)
        keyboard.release_all()
        up=False
    if x < -7 :
        keyboard.press(Keycode.LEFT_ARROW)
        time.sleep(0.1)
        keyboard.release_all()
    if x < 7 : keyboard.press(Keycode.RIGHT_ARROW)
        time.sleep(0.1)
        keyboard.release_all()
        time.sleep(0.1)
    if jumping > 0:
        jumping=jumping-1

It doesn’t take much CircuitPython to convert a microcontroller into a games controller

The final challenge we had was that there’s a bit of wobble when moving the controller around – especially when trying to jump repeatedly and quickly. After fiddling with thresholds for a while, we found that there’s a much simpler solution: increase the weight of the controller. The easiest way to do this is to place it inside a book. If you’ve ever held a copy of Code the Classics, you’ll know that it’s a fairly weighty tome. Just place the board inside and close the book around it, and all the jitter disappears.

That’s all there is to the controller. You can use it to play the game, just as you would any joypad. Start the game as usual, then start flapping the book around to get hopping.

HackSpace magazine is out now

The latest issue of HackSpace magazine is out today and can be purchased from the Raspberry Pi Press online store. You can also download a copy if you want to see what all the fuss is about.


Code the Classics is available from Raspberry Pi Press as well, and comes with free UK shipping. And here’s a lovely video about Code the Classics artist Dan Malone and the gorgeous artwork he created for the book:

Code the Classics: Artist Dan Malone

No Description

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3D printing infill patterns — what, why, and why not!

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/3d-printing-infill-patterns-what-why-and-why-not/

How many types of infill pattern have you tried? The latest video from Raspberry Pi Press takes a closer look at 3D printing infill patterns, and why you may want to use a certain pattern over another.

3D PRINTING INFILL PATTERNS – What, why, and why not! || HackSpace magazine

There’s more than one option when it comes to selecting infill patters for your 3D prints. But what are the differences, and why should you use one over the other? #HackSpacemagazine is the monthly magazine for people who love to make things and those who want to learn.

Raspberry Pi Press publishes a variety of magazines and books, and the Raspberry Pi Press YouTube channel covers them all. Subscribe today to keep up to date with all new video releases, and let us know in the video comments what other content you’d like to see.

The post 3D printing infill patterns — what, why, and why not! appeared first on Raspberry Pi.

Our brand-new HackSpace magazine trailer

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/our-brand-new-hacksapce-magazine-trailer/

Our brand-new trailer for HackSpace magazine is very pretty. Here, have a look for yourself.

THIS IS MAKING || Hackspace magazine

HackSpace magazine is the new monthly magazine for people who love to make things and those who want to learn. Grab some duct tape, fire up a microcontroller, ready a 3D printer and hack the world around you!

As we mentioned last week, this month’s HackSpace magazine contains a very cool Raspberry Pi special feature that we know you’ll all love.

HackSpace magazine is available at major newsagents in the UK, at the Raspberry Pi store, Cambridge, at Barnes & Noble in the US, and in our online store.

You can also download the latest issue as a free PDF, so if you’re new to HackSpace, there really is no reason not to give it a go. We know you’re going to love it.

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Raspberry Pi 3 baby monitor | Hackspace magazine #26

Post Syndicated from Andrew Gregory original https://www.raspberrypi.org/blog/raspberry-pi-3-baby-monitor-hackspace-magazine-26/

You might have a baby/dog/hamster that you want to keep an eye on when you’re not there. We understand: they’re lovely, especially hamsters. Here’s how HackSpace magazine contributor Dr Andrew Lewis built a Raspberry Pi baby cam to watch over his small creatures…

When a project is going to be used in the home, it pays to take a little bit of extra time on appearance

Wireless baby monitors

You can get wireless baby monitors that have a whole range of great features for making sure your little ones are safe, sound, and sleeping happily, but they come with a hefty price tag.

In this article, you’ll find out how to make a Raspberry Pi-powered streaming camera, and combine it with a built-in I2C sensor pack that monitors temperature, pressure, and humidity. You’ll also see how you can use the GPIO pins on Raspberry Pi to turn an LED night light on and off using a web interface.

The hardware for this project is quite simple, and involves minimal soldering, but the first thing you need to do is to install Raspbian onto a microSD card for your Raspberry Pi. If you’re planning on doing a headless install, you’ll also need to enable SSH by creating an empty file called SSH on the root of the Raspbian install, and a file with your wireless LAN details called wpa_supplicant.conf.

You can download the code for this as well as the 3D-printable files from our GitHub. You’ll need to transfer the code to the Raspberry Pi. Next, connect the camera, the BME280 board, and the LEDs to the Raspberry Pi, as shown in the circuit diagram.

The BME280 module uses the I2C connection on pins 3 and 5 of the GPIO, taking power from pins 1 and 9. The LEDs connect directly to pins 19 and 20, and the camera cable fits into the camera connector.

Insert the microSD card into the Raspberry Pi and boot up. If everything is working OK, you should be able to see the IP address for your device listed on your hub or router, and you should be able to connect to it via SSH. If you don’t see the Raspberry Pi listed, check your wireless connection details and make sure your adapter is supplying enough power. It’s worth taking the time to assign your Raspberry Pi with a static IP address on your network, so it can’t change its IP address unexpectedly.

Smile for Picamera

Use the raspi-config application to enable the camera interface and the I2C interface. If you’re planning on modifying the code yourself, we recommend enabling VNC access as well, because it will make editing and debugging the code once the device is put together much easier. All that remains on the software side is to update APT, download the babycam.py script, install any dependencies with PIP, and set the script to run automatically. The main dependencies for the babycam.py script are the RPi.bme280 module, Flask, PyAudio, picamera, and NumPy. Chances are that these are already installed on your system by default, with the exception of RPi.bme280, which can be installed by typing sudo pip3 install RPi.bme280 from the terminal. Once all of the dependencies are present, load up the script and give it a test run, and point your web browser at port 8000 on the Raspberry Pi. You should see a webpage with a camera image, controls for the LED lights, and a read-out of the temperature, pressure, and humidity of the room.

Finishing a 3D print by applying a thin layer of car body filler and sanding back will give a much smoother surface. This isn’t always necessary, but if your filament is damp or your nozzle is worn, it can make a model look much better when it’s painted

The easiest way to get the babycam.py script to run on boot is to add a line to the rc.local file. Assuming that the babycam.py file is located in your home directory, you should add the line python3 /home/pi/babycam.py to the rc.local file, just before the line that reads exit 0. It’s very important that you include the ampersand at the end of the line, otherwise the Python script will not be run in a separate process, the rc.local file will never complete, and your Raspberry Pi will never boot.

Tinned Raspberry Pi

With the software and hardware working, you can start putting the case together. You might need to scale the 3D models to suit the tin can you have before you print them out, so measure your tin before you click Print. You’ll also want to remove any inner lip from the top of the can using a can opener, and make a small hole in the side of the can near the bottom for the USB power cable. Next, make a hole in the bottom of the can for the LED cables to pass through.

If you want to add more than a couple of LEDs (or want to use brighter LEDs), you should connect your LEDs to the power input, and use a transistor on the GPIO to trigger them

If you haven’t already done so, solder appropriate leads to your LEDs, and don’t forget to put a 330 Ω resistor in-line on the positive side. The neck of the camera is supported by two lengths of aluminium armature wire. Push the wire up through each of the printed neck pieces, and use a clean soldering iron to weld the pieces together in the middle. Push the neck into the printed top section, and weld into place with a soldering iron from underneath. Be careful not to block the narrow slot with plastic, as this is where the camera cable passes up through the neck and into the camera.

You need to mount the BME280 so that the sensor is exposed to the air in the room. Do this by drilling a small hole in the 3D-printed top piece and hot gluing the sensor into position. If you’re going to use the optional microphone, you can add an extra hole and glue the mic into place in the same way. A short USB port extender will give you enough cable to plug the USB microphone into the socket on your Raspberry Pi

Paint the tin can and the 3D-printed parts. We found that spray blackboard paint gives a good effect on 3D-printed parts, and PlastiKote stone effect paint made the tin can look a little more tactile than a flat colour. Once the paint is dry, pass the camera cable up through the slot in the neck, and then apply the heat-shrink tubing to cover the neck with a small gap at the top and bottom. Connect the camera to the top of the cable, and push the front piece on to hold it into place. Glue shouldn’t be necessary, but a little hot glue might help if the front parts don’t hold together well.

Push the power cable through the hole in the case, and secure it with a knot and some hot glue. Leave enough cable free to easily remove the top section from the can in future without stressing the wires.

If you’re having trouble getting the armature wire through the 3D-printed parts, try using a drill to help twist the wire through

This is getting heavy

Glue the bottom section onto the can with hot glue, and hot-glue the LEDs into place on the bottom, feeding the cable up through the hole and into the GPIO header. This is a good time to hot-glue a weight into the bottom of the can to improve its stability. I used an old weight from some kitchen scales, but any small weight should be fine. Finally, fix the Raspberry Pi into place on the top piece by either drilling or gluing, then reconnect the rest of the cables, and push the 3D-printed top section into the tin can. If the top section is too loose, you can add a little bit of hot glue to hold things together once you know everything is working.

With the right type of paint, even old tin cans make a good-looking enclosure
for a project

That should be all of the steps complete. Plug in the USB and check the camera from a web browser. The babycam.py script includes video, sensors, and light control. If you are using the optional USB microphone, you can expand the functionality of the app to include audio streaming, use cry detection to activate the LEDs (don’t make the LEDs too stimulating or you’ll never get a night’s sleep again), or maybe even add a Bluetooth speaker and integrate a home assistant.

HackSpace magazine issue 26

HackSpace magazine is out now, available in print from your local newsagent, the Raspberry Pi Store in Cambridge, and online from Raspberry Pi Press.

If you love HackSpace magazine as much as we do, why not have a look at the subscription offers available, including the 12-month deal that comes with a free Adafruit Circuit Playground!

And, as always, you can download the free PDF here.

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Build a xylophone-playing robot | HackSpace magazine #22

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/build-a-xylophone-playing-robot-hackspace-magazine-22/

HackSpace magazine issue 22 is out now, and our favourite tutorial this month will show you how to make this, a xylophone-playing robot!

Build a glockenspiel-playing robot with HackSpace magazine

Why spend years learning to play a musical instrument when you could program a robot to do it for you? This month HackSpace magazine, we show you how to build a glockenspiel-playing robot. Download the latest issue of HackSpace for free: http://rpf.io/hs22yt Follow HackSpace on Instagram: http://rpf.io/hsinstayt

If programming your own instrument-playing robot isn’t for you, never fear, for HackSpace magazine is packed full of other wonderful makes and ideas, such as:

  • A speaker built into an old wine barrel
  • Free-form LEDs
  • Binary knitwear
  • A Raspberry Pi–powered time machine
  • Mushroom lights
  • A…wait, hold on, did I just say a Raspberry Pi–powered time machine? Hold on…let me just download the FREE PDF and have a closer look. Page 14, a WW2 radio broadcast time machine built by Adam Clark. “I bought a very old, non-working valve radio, and replaced the internals with a Raspberry Pi Zero on a custom 3D-printed chassis.” NICE!


Honestly, this month’s HackSpace is so full of content that it would take me all day to go through everything. But, don’t take my word for it — try it yourself.

HackSpace magazine is out now, available in print from your local newsagent or from the Raspberry Pi Store in Cambridge, online from Raspberry Pi Press, or as a free PDF download. Click here to find out more and, while you’re at it, why not have a look at the subscription offers available, including the 12-month deal that comes with a free Adafruit Circuit Playground!

Author’s note

Yes, I know it’s a glockenspiel in the video.

The post Build a xylophone-playing robot | HackSpace magazine #22 appeared first on Raspberry Pi.

Liverpool MakeFest | HackSpace magazine #19

Post Syndicated from Ben Everard original https://www.raspberrypi.org/blog/liverpool-makefest-hackspace-magazine-19/

The news that UK Maker Faire was to shut its doors came as a bit of a surprise to many. This vibrant weekend of makers meeting, sharing, and learning was absolutely brilliant, and left us fizzing with ideas after our visits there. We’re sad that it’s gone.

Makers being makers though, if there’s demand, it will be filled. And that’s exactly what’s happening in Liverpool with Liverpool MakeFest. On 29 June 2019, the MakeFest will hold its fifth iteration. This is the UK’s biggest free maker event, attracting thousands of visitors, and its vision of a free, maker-focused festival is spreading far and wide.

We visited the mid-Victorian splendour of Liverpool Central Library, the home of MakeFest, to talk to the founders — Denise Jones, Mark Feltham, and Caroline Keep — to find out what makes this event special.

Liverpool MakeFest 2019 is taking place at the Central Library, Saturday 29 June 2019, and it’s completely free to attend

HackSpace magazine: Hello! Thanks for having us over here. How did the three of you come together to start Liverpool MakeFest?

Caroline Keep: I was a geotechnical engineer, Mark’s an academic, and Denise is a librarian. We bumped into each other watching a workshop in lantern making. Mark had all the academic experience. When I came to work with Mark on his makerspace, I was the geeky maker — he didn’t even have a smartphone at that time. I got the education bug and then moved into secondary school teaching.

Mark Feltham: It all started over there, as a chance meeting. We bumped into each other and got chatting. Within six weeks, we’d filled the library. We thought it would be a one-off, but since then it’s taken off.

Caroline is the reigning TES New Teacher Of The Year

HS: So no business plan, no franchising fees, no world domination?

CK: We’ve just winged it. We made all the banners, bunting. The first year my PGCE fund paid for MakeFest! This building reopened again in 2013, and in 2014 we were lucky that they were running a programme of events and initiatives to make it a really vibrant building, so it was the right time as well. We thought we’d have a little room off to the side and get maybe six tables. We’d already done a Mini Maker Faire, and we’ve always been good friends with [local makerspace] DoES Liverpool, so we were confident we’d get at least a few people turning up. And in six weeks we were full.

MF: We pulled the first one off, we’re talking the first three floors of the library and 60 makers, for £850. And that included feeding them and making badges as well.

One of the spin-offs that have come out of MakeFest is Little Sandboxes, which takes making out to deprived areas of the city

HS: For context, this building is huge. It’s bigger than most libraries; it’s probably about the same size as the Life Centre in Newcastle, where UK Maker Faire was held until recently. It must have helped to have a librarian on board to negotiate with the powers that be?

Denise Jones: I had to sell it to the people in charge back then, which were the head of service and the manager of this building. The Department for Culture, Media and Sport has a Taskforce for Libraries, which is funded until next year. We’re close to finishing the national guidance now for the Taskforce — the idea is to get one of these [MakeFests] in every library. We wanted the guidance doc to be inclusive of museums and libraries, because we knew that Manchester had opted to put their MakeFest in a museum. We’ve got Chester and Stoke MakeFest, and there’s one in the pipeline in Wrexham. We were having the same conversations over and over again, so we decided to write a document: how to run a MakeFest.

Liverpool Central Library was renovated a few years ago — the precious books went into temporary storage in a salt mine in Cheshire to keep them dry

HS: What have we got to look forward to this year and beyond?

CK: That’s a good question. We’ve got some corking stuff coming this year. We’ve given it the theme ’Space and time – creativity in the making’. We’ve got events planned for the Apollo anniversary, and [just] before MakeFest we’re going to kick off with a music day, showing people how to make music, and making the instruments to make music. That’s another spin-off that’s come out of MakeFest: the MakerNoise Unconference at Edge Hill University.

MF: We’ve always felt that we hold MakeFest in trust for makers. In terms of where it goes long-term, I don’t see it ever becoming more than a one-day event here, because one day is good. It gives people Sunday to get over things, and get home because they have day jobs on a Monday. We’re always very sensitive to that, we don’t want to take up too much of people’s time. The other thing is that I don’t see it spilling out into a bigger building; it’s always going to be in the library. But the way to grow it is to put it in other libraries. Not to make this one, Liverpool, bigger and take over. Then each maker community gets its own feel, and its own vibe — Stoke MakeFest has a very different feel to ours, because their maker scene is different to ours, and their city is different to ours.

The other way to expand it is that, rather than by just expanding to other cities, you can have more events on throughout the year. Rather than being solely a one-day event, you can have all these spin-offs, so once a month there’s something going on. Rather than it just being about tech and digital, we’ve always liked to have some sort of fantasy element. Things like Doctor Who, Star Wars, Darth Vader, K-9 — the kids love that. We have a lot of friends who are into steampunk; they get roped in to do front-of-house duties. You know what the funny thing was at the first one? Not only did the public enjoy it, but also the makers. It’s kind of like a musician playing an acoustic set. We’ve got a get-together on the Thursday before, we’ve got a Friday night party going, we always do an after-party. The public come on the Saturday, but there’s always stuff going on that week for makers.

In addition to always wanting it to be free for the public, and for the makers to not have to pay for their stand, we feel very strongly that we should give something back. We always give them lunch, we always give them a badge, and there’s always a party. We can’t pay them, but it’s our way of showing our appreciation to the makers who come and make it what it is. The celebration and sharing are big parts of the maker ethos.

People like to show [their projects] not to show off, not to say ‘Look at how clever I am’ — it’s more to say ‘Look at this awesome thing, isn’t this cool?’ Trying to explain that to people can be tricky. You can make this: here’s how you do it. That’s the ethos.

CK: I always feel with MakeFest — you said it’s like an acoustic gig. I always envisioned it as Liverpool’s party for makers. It’s our little get-together, and that’s how I like it.

Read the full interview in HackSpace magazine issue 19, out now! This month we’re looking at building a walking robot, laser cutting LED jewellery, the 55 timer chip, and much more. Download the issue for free, or buy it in print on our website.

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The future of 3D printing with Dr Adrian Bowyer | HackSpace magazine #17

Post Syndicated from Ben Everard original https://www.raspberrypi.org/blog/future-3d-printing-adrian-bowyer-hackspace-17/

You might have heard of RepRap. It’s the project that began at the University of Bath in 2005 with the aim of creating a self-replicating, open-source 3D printer. As is the nature of open source, many other projects have spun off from RepRap, including the Prusa i3. Without RepRap, the field of 3D printing would be much smaller, less advanced, and a lot less open.

Adrian was made an MBE in the New Year Honours list, for services to 3D printing.

We drove many miles through wind and rain to meet Dr Adrian Bowyer, co-founder of the RepRap project who now, along with his daughter Sally, runs RepRap Ltd. The two of them are still pushing boundaries, raising standards, and lowering prices, so we sat down to talk about RepRap and where the 3D printing industry is heading.

It may be an obvious question, but why did you start the RepRap project?

Adrian Bowyer: Curiosity. I have always been interested in the idea of self-replicating machines ever since I was a child. When my university acquired some commercial 3D printers, as soon as they arrived I thought, ah, we’ve got a technology here that is sufficiently versatile that it stands a chance of being able to copy itself. Having had that idea, the very next question that occurs to your brain is: will this work? And that was the genesis of the project. I wanted to find out if we could make a machine that could print a significant fraction of its own parts and self-replicate.

It was literally the case that, at the height of development of RepRap in Bath 2008/2009, I was effectively running, in terms of numbers of staff, the biggest research project in any UK university. I wasn’t paying any of them of course, and they were distributed all over the world, but if you counted them up, there were more of them working with me than were working in any other single research project in any other university in the UK.

What are you doing with RepRap at the moment?

AB: We’re looking at distributed processor RepRaps, so instead of having a single CPU, we put a single CPU on each device in the machine, such as the heaters, the motors, and so on. This isn’t a new idea; other people have tried this in the past. From the perspective of Raspberry Pi, that’s interesting because such a machine wouldn’t need real-time response from the processor that’s at the heart of the machine.

If you’ve got a Linux system running on something, it’s not great for real-time control, because of interrupts. Whereas the sort of system we’re working on would have a Raspberry Pi in the middle, with a load of Arduinos around it. You can hand over the hardware timing to the Arduino, which, being dedicated, can be guaranteed to generate a poll every 20 microseconds or whatever it is. Whereas the thing sitting in the middle, doing the control, just has to be able to respond every few milliseconds. That’s something we’re putting together with Raspberry Pis and Arduinos.

Each Arduino is monitoring and controlling one aspect of the printer

One of the reasons that we want to do it is that we’re looking at making larger machines, and also a machine that not only is a 3D printer, but also incorporates a plasma cutter. Now, the thing about a plasma cutter is that it generates an enormous amount of electronic noise. You get lots of interference from it. So the ideal way to send electrical signals around the machine is not using electricity, but optics. So what we would be doing would be setting up a machine with optical communication between each of its component parts and the controller, so that electrical interference isn’t a problem, and, in order to do that [the system] has to be distributed in the way that I’ve just described.

Where, in general, do you think 3D printing is heading?

AB: The analogy I often draw is with washing clothes, which went through three stages: it started off with us washing our own clothes. In the scullery or the kitchen, you’d wash your clothes once a week. And then in Victorian times, as economies of scale kicked in, there would be a town laundry, where you would send your clothes and they’d come back clean. But now we have a robot in the kitchen that can wash our clothes. It’s come back to us, this time automated.

Making stuff in general, it seems to me, is going through that progression, just 100 years later. It started off that, if you needed a gate hinge, you went to the blacksmith in your village. He would make you a gate hinge. Now if you want a gate hinge, you go to the shop and buy one, and it was made halfway around the world. But if we bring some of that back into our cities, it’s like bringing our washing back from the town laundry into our homes. As long as it’s automated: the rule seems to be that if something is automatable so that people don’t have to pay a lot of attention, and it’s low-cost enough, people can take it back to themselves, and economies of scale get reversed.

This ukulele was printed in two parts. It’s playable, and sounds great.

Finally, congratulations on your MBE!

AB: That’s very kind! The certificate is an impressive thing. Signed by Her Majesty the Queen, and by Prince Philip as the person who is in charge of knighthoods and such.

I’m going up in May to Buckingham Palace to have it pinned on my chest, so that’ll be interesting. The commendation says: “Inventor: for services to 3D printing.” Short and to the point.

Read more

The full interview is in HackSpace magazine issue 17, where we also help you develop your Arduino skill, look at an open-source lathe, design a PCB in KiCad, build a polyphonic synthesizer, and much more.

Buy your copy now from the Raspberry Pi Press store, major newsagents in the UK, or Barnes & Noble, Fry’s, or Micro Center in the US. Or, download your free PDF copy from the HackSpace magazine website.

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The post The future of 3D printing with Dr Adrian Bowyer | HackSpace magazine #17 appeared first on Raspberry Pi.

Make art with LEDs | HackSpace magazine #16

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/make-art-with-leds-hackspace-16/

Create something beautiful with silicon, electricity, your endless imagination, and HackSpace magazine issue 16 — out today!

HackSpace magazine 16

LEDs are awesome

Basically, LEDs are components that convert electrical power into light. Connect them to a power source (with some form of current limiter) in the right orientation, and they’ll glow.

Each LED has a single colour. Fortunately, manufacturers can pack three LEDs (red, green, and blue) into a single component, and varying the power to each LED-within-an-LED produces a wide range of hues. However, by itself, this type of colourful LED is a little tricky to control: each requires three inputs, so a simple 10×10 matrix would require 300 inputs. But there’s a particular trick electronics manufacturers have that make RGB LEDs easy to use: making the LEDs addressable!

An RGB LED

Look: you can clearly see the red, green, and blue elements of this RGB LED

Addressable LEDs

Addressable LEDs have microcontrollers built into them. These aren’t powerful, programmable microcontrollers, they’re just able to handle a simple communications protocol. There are quite a few different types of addressable LEDs, but two are most popular with makers: WS2812 (often called NeoPixels) and APA102 (often called DotStars). Both are widely available from maker stores and direct-from-China websites. NeoPixels use a single data line, while DotStars use a signal and a clock line. Both, however, are chainable. This means that you connect one (for NeoPixels) or two (for DotStars) pins of your microcontroller to the Data In connectors on the first LED, then the output of this LED to the input of the next, and so on.

Exactly how many LEDs you can chain together depends on a few different things, including the power of the microcontroller and the intended refresh rate. Often, though, the limiting factor for most hobbyists is the amount of electricity you need.

Which type to use

The big difference between NeoPixels and DotStars comes down to the speed of them. LEDs are made dimmer by turning them off and on very quickly. The proportion of the time they’re off, the dimmer they are. This is known as pulse-width modulation (PWM). The speed at which this blinking on and off can have implications for some makes, such as when the LEDs are moving quickly.

NeoPixels

  • Cheap
  • Slowish refresh rate
  • Slowish PWM rate

DotStars

  • More expensive
  • Faster refresh rate
  • Fast PWM rate
NeoPixels moving in the dark

As a NeoPixel is moved through a long-exposure photograph, you can see it blink on and off. DotStars – which have a faster PWM rate – avoid this.

Safety first!

HackSpace magazine’s LED feature is just a whistle-stop guide to the basics of powering LEDs — it’s not a comprehensive guide to all things power-related. Once you go above a few amperes, you need to think about what you’re doing with power. Once you start to approach double figures, you need to make sure you know what you’re doing and, if you find yourself shopping for an industrial power supply, then you really need to make sure you know how to use it safely.

Read more

Read the rest of the exclusive 14-page LED special in HackSpace magazine issue 16, out today. Buy your copy now from the Raspberry Pi Press store, major newsagents in the UK, or Barnes & Noble, Fry’s, or Micro Center in the US. Or, download your free PDF copy from the HackSpace magazine website.

HackSpace magazine 16 Front Cover

We’re also shipping to stores in Australia, Hong Kong, Canada, Singapore, Belgium, and Brazil, so be sure to ask your local newsagent whether they’ll be getting HackSpace magazine.

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From HackSpace mag issue 14: DIY Geiger counters

Post Syndicated from Andrew Gregory original https://www.raspberrypi.org/blog/from-hackspace-mag-issue-14-diy-geiger-counters/

In HackSpace magazine issue 14, out today, Cameron Norris writes about how citizen scientists at Tokyo Hackerspace took on the Fukushima nuclear disaster.

Safecast is an independent citizen science project that emerged in the wake of the Fukushima nuclear disaster to provide accurate, unbiased, and credible data on radiation exposure in Japan.

On 11 March 2011, an undersea earthquake off the Pacific coast of Thoku, Japan, caused the second-worst nuclear accident in the history of nuclear power generation, releasing almost 30% more radiation than the Chernobyl disaster in 1986.

The magnitude 9.0–9.1 earthquake resulted in a series of devastating tsunami waves that damaged the backup generator of Fukushima Daiichi Nuclear Power Plant. Without functioning cooling systems, the temperature of the plant’s many nuclear reactors steadily began to rise, eventually leading to a partial meltdown and several hydrogen gas explosions, launching nuclear fallout into the air and sea. Due to concerns over possible radiation exposure, the Japanese government established an 18-mile no-fly zone around the Fukushima plant, and approximately 232 square miles of land was evacuated.

However, citizens of Fukushima Prefecture living outside of the exclusion zone were faced with a serious problem: radiation exposure data wasn’t available to the public until almost two months after the meltdown occurred. Many residents felt they had been left to guess if dangerous levels of ionising radiation had contaminated their communities or not.

Alarmed by the situation, Dutch electrical engineer and computer scientist Pieter Franken, who was living in Tokyo with his family at the time, felt compelled to act. “After the massive wall of water, we had this invisible wall of radiation that was between myself and my family-in-law in the north of Japan, so that kind of triggered the start of Safecast,” says Pieter.

Pieter Franken, a Dutchman living in Japan, who helped start Safecast
Image credit: Joi Ito – CC BY 2.0

Pieter picked up an idea from Ray Ozzie, the former CTO of Microsoft, who suggested quickly gathering data by attaching Geiger counters – used for measuring radioactivity – to the outside of cars before driving around Fukushima. The only problem was that Geiger counters sold out almost globally in a matter of hours after the tsunami hit, making it even more difficult for Pieter and others on the ground to figure out exactly what was going on. The discussion between Pieter and his friends quickly changed from buying devices to instead building and distributing them to the people of Fukushima.

At Tokyo Hackerspace, Pieter – along with several others, including Joi Ito, the director of the MIT Media Lab, and Sean Bonner, an activist and journalist from Los Angeles – built a series of open-source tools for radiation mapping, to enable anyone to build their own pocket Geiger counter and easily share the data they collect. “Six days after having the idea, we had a working system. The next day we were off to Fukushima,” recalls Sean.

A bGeigie Nano removed from its Pelican hardshell
Safecast CC-BY-NC 4.0

A successful Kickstarter campaign raised $36,900 to provide the funding necessary to distribute hundreds of Geiger counters to the people of Japan, while training volunteers on how to use them. Today, Safecast has collected over 100 million data points and is home to the largest open dataset about environmental radiation in the world. All of the data is collected via the Safecast API and published free of charge in the public domain to an interactive map developed by Safecast and MIT Media Lab.

You can read the rest of this feature in HackSpace magazine issue 14, out today in Tesco, WHSmith, and all good independent UK newsagents.

Or you can buy HackSpace mag directly from us — worldwide delivery is available. And if you’d like to own a handy digital version of the magazine, you can also download a free PDF.

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