Tag Archives: hackspace

OctoPrint: a baby monitor for your 3D printer

via Raspberry Pi

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

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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

via Raspberry Pi

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

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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

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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 cp
x, 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

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Play Pong with ultrasonic sensors and a Raspberry Pi | HackSpace magazine

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Day three of our Pong celebration leads us here, to HackSpace magazine’s ultrasonic hack of Eben’s Code the Classics Pong tribute, Boing!

If you haven’t yet bought your copy of Code the Classics, you have until 11:59pm GMT tonight to get £1 off using the discount code PONG. Click here to visit the Raspberry Pi Press online store to secure your copy, and read on to see how you can use ultrasonic sensors to turn this classic game into something a lot more physical.

Over to the HackSpace magazine team…

Code the Classics is an entertaining book for a whole bunch of reasons, but one aspect of it that is particularly exciting to us makers is that it means there are some games out there that are really fun to play, but also written to be easy to understand and have high-quality game art to go along with them. Why does this excite us as makers? Because it makes them ideal candidates for testing out novel DIY games controllers!

Pong

We’re going to start right at the beginning of the book (and also at the beginning of computer game history) with the game Pong. There’s a great chapter on this seminal game in the book, but we’ll dive straight into the source code of our Boing! tribute game. This code should run on any computer with Python 3 (and a few dependencies) installed, but we’ll use a Raspberry Pi, as this has GPIO pins that we can use to add on our extra controller.

Download the code here by clicking the ‘Clone or download’ button, and then ‘Download ZIP’. Unzip the downloaded file, and you should have a directory called Code‑The‑Classics-master, and inside this, a directory called boing-master.

Open a terminal and navigate to this directory, then run:

python3 boing.py

If everything works well, you’ll get a screen asking you to select one or two players – press SPACE to confirm your selection, and have a play.

Hacking Code the Classics

So that’s how Eben Upton designed the game to be played. Let’s put our own spin on it. Games controllers are basically just sensors that take input from the real world in some way and translate that into in-game actions. Most commonly, these sensors are buttons that you press, but there’s no need for that to be the case. You can use almost any sensor you can get input from – it sounds trite, but the main limitation really is your imagination!

We were playing with ultrasonic distance sensors in the last issue of HackSpace magazine, and this sprung to mind a Pong controller. After all, distance sensors measure in one dimension and Pong bats travel in one dimension.

Last issue we learned that the main challenge when using the cheap HC-SR04 sensors with 3.3V devices is that they use 5V, so we need to reduce their output to 3.3V. A simple voltage divider does the trick, and we used three 330Ω resistors to achieve this – see Figure 1 for more details.

There’s support for these sensors in the GPIO Zero Python library. As a simple test, you can obtain the distance with the following Python code:

import gpiozero
import time
sensor = gpiozero.DistanceSensor(echo=15,trigger=14)

while True:
    print(sensor.distance)

time.sleep(0.1)

That will give you a constant read-out of the distance between the ultrasonic sensor and whatever object is in front of it. If you wave your hand around in front of the sensor, you’ll see the numbers changing from 0 to 1, which is the distance in metres.

So far, so straightforward. We only need to add a few bits to the code of our Boing! game to make it interact with the sensor. You can download an updated version of Boing! here, but the changes are as follows.

Add this line to the import statements at the top:

import gpiozero

Add this line to instantiate the distance sensor object at the end of the file (just before pgzrun.go()):

p1_distance = DistanceSensor(echo=15,trigger=14,queue_len=5)

We added the queue_len parameter to get the distances through a little quicker.

Finally, overwrite the p1_controls function with the following:

def p1_controls():
    move = 0
    distance = p1_distance.distance
    print(distance)
    if distance < 0.1:
        move = PLAYER_SPEED
    elif distance > 0.2:
        move = -PLAYER_SPEED
    return move

This uses the rather arbitrary settings of 10 cm and 20 cm to define whether the paddle moves up or down. You can adjust these as required.

That’s all there is to our ultrasonic Pong. It’s great fun to play, but there are, no doubt, loads of other versions of this classic game you can make by adding different sensors. Why not see what you can come up with?

Code the Classics

Today is the last day to get £1 off Code the Classics with the promo code PONG, so visit the Raspberry Pi Press online store to order your discounted copy before 11:59pm GMT tonight.

You can also download Code the Classics as a free PDF here, but the book, oh, the book – it’s a marvellous publication that deserves a physical presence in your home.

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