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Raspberry Pi Programming Workshop

RPiPW = resources + notes + code samples for a workshop introducing the Raspberry Pi as a beginner's programming environment

Table of Contents

The Raspberry Pi

The Raspberry Pi is a low-cost, low-power single board computer the size of a credit card. With a low price point and advanced software, it is a great tool to teach youth electronics and programming.

The Pi is developed by the Raspberry Pi Foundation. Their goal is ''to advance the education of adults and children, particularly in the field of computers, computer science and related subjects,'' according to their about us page.

Children buy $60 video games for expensive consoles each year. What if they purchased a computer with that money instead? They could take the same HDMI cable out of their video game system and plug it into a Raspberry Pi.

Breakdown of various available models of the Raspberry Pi

Release Date Original Price Model GPIO Pins CPU
Feb 2016 $35 3 B 40 1.2GHz ARMv8 64bit (quad core)
Nov 2015 $5 Zero 40 1.0GHz ARMv6 (single core)
Feb 2015 $35 2 B 40 900MHz ARMv7 (quad core)
Nov 2014 $20 1 A+ 40 700MHz ARMv6 (single core)
July 2014 $25 1 B+ 40 700MHz ARMv6 (single core)
Apr 2014 $30 Compute 200 700MHz ARMv6 (single core)
Feb 2012 $25 1 A 26 700MHz ARMv6 (single core)
Feb 2012 $35 1 B 26 700MHz ARMv6 (single core)

There are other SBCs (Single Board Computers) available. The Raspberry Pi is not the best, but the Raspberry Pi is one of the cheapest and most popular boards. Other SBCs include OEMA68, Parallella with 18 core processors, OLinuXino, Banana Pi, C.H.I.P. the $9 base modular computer, Beagleboards, and Cubieboards. With anything popular in the open source community, higher numbers of people working on a projects yields more projects, tutorials, and development. I started with the journey into single board computers with the Raspberry Pi model 1 B.

Electricity efficiency: A typical desktop computer without a monitor consumes 200 W 800 mA. If you were to leave a full computer running all day for a year, you would be using 1752 kilowatt-hours or about $630 on your electric bill. A 5 W Raspberry Pi running all day for a year would use 43.8 kilowatt-hours or about $15. This makes a large environmental difference for long-term projects like hosting a web server or opening your garage when your phone comes within range.

Purchasing a Raspberry Pi

What about all of the extra things you need to make it work? I made a shopping cart at the Cambridge, MA Micro Center page with everything I would buy for one.

  • $29.99 RS Raspberry Pi 3 Model B

  • $8.99 Micro-USB Power Supply 5 volt 2.5 amp

  • $3.99 Inland Wired Optical Mouse

  • $3.99 Inland Wired Keyboard

  • $5.99 Micro Center 16GB micro SDHC Class 10 Flash Media Card

  • $52.95 Subtotal

  • $4.50 Tax

  • $57.45 Grand Total

Some of these items are commonly lying around already. Cheaper prices can be found at other online stores, thrift stores, and garage sales. Three things that I did not include are a case, and HDMI cable, and a screen with HDMI or DVI. Optionally, Legos or a 3D printer can be used to build a case. TVs are almost everywhere.

Another ready to go option is the pi-top for $300 or the pi-topCEED for $150 which are Raspberry Pi workstations that include monitors.

Operating Systems for the Raspberry Pi

There are many different operating systems available for the Raspberry Pi. My personal favorite is Arch for Arm as it is the fastest operating system for the Pi that I am aware of. For this tutorial, I will use Raspbian because it contains software to get started, has excellent community support, and most project tutorials use Raspbian as a starting point.

Why GNU/Linux? GNU/Linux is built on free and open source software and can be easily downloaded, modified, distributed, and used with few to no restrictions. This is very beneficial for a programming environment. GNU/Linux is also used by the most advanced science and technology institutions such as the International Space Station, CERN, US Navy, US DOD, FAA, USPS, Google, Novell, IBM, Cisco, and Amazon.
Other operating systems to note are pi-topOS, Fedberry, OpenWRT, RISC OS, OSMC, FreeBSD, and many more. You can even make your own operating system for the Raspberry Pi.

Installing Raspbian via NOOBS

The Raspberry Pi usually does not come with an operating system or storage. You run the operating system from a microSD. If you have never installed or experimented with GNU/Linux before, use NOOBS. It was made to be as easy as possible. If you mess it up, hold shift while you boot and reinstall.

Video tutorial of installing NOOBS https://www.raspberrypi.org/help/noobs-setup/

  1. Download this large zip file to your other computer: https://downloads.raspberrypi.org/NOOBS_latest

  2. You will need a class 10 microSD card greater than or equal to 8GB. If you have other files on the microSD card you will be using, back those up to another location, then format the microSD card to FAT32. Extract all of the files directly to a microSD card.

  3. Put the microSD card into the Raspberry Pi and plug in your power supply. The Raspberry Pi will light up.

  4. A menu of operating systems appears. Put a check next to Raspbian. At the Bottom of the screen change the international options to your country. I choose US. There are many differences between a keyboard in the United States and one in Great Britain. Click ''Install'' and wait a long while.

  5. You have an Operating System!

If copying files to a microSD card is too daunting of a task, preinstalled cards are also available for purchase.

Software Repositories

Every GNU/Linux distribution has a set of software that can be installed for free called a repository. The App Store and Google Play store were based on the concept of a repository. All of your software can be installed and updated from one central place. To get a visual glipse of the repository, I like to use a program called ''synaptic''.

IMPORTANT: To open a terminal in Raspbian, click on the black rectangle in the upper left of the screen.
To install synaptic, run this command in a terminal:

sudo apt-get install -y synaptic

Relevant XKCD:

Open synaptic, click the update button to get the latest list of programs, and then page down to browse. That is an incredibly large list of programs. All of them are absolutely free. Most of them are open source. The search button at the top right allows you to search for keywords in the name and description.

Introduction to Programming

I would love to teach everyone to program in a day. That is not possible. I can show you some cool things you can do with programming. I can tell you how to learn more. You will have to do more on your own, practice, find a project that you can work on during your spare time, search for solutions, read code and tutorials, communicate with other programmers, ask questions, and have fun making new things.

Why should you use the Raspberry Pi for programming? I see lots of web developers use these shiny, expensive laptops. They design engaging interactive websites. They put them out on the Internet and then the result does not work for the majority of computers. They write it off and say, "Oh, well. It works for me." That attitude does not change the situation they face. Many people cannot use their website. Had they developed on a low spec Raspberry Pi, the result should work on any computer or phone.

I will be using Python for these examples. Python is an easy-to-read, beginner programming language that can do almost anything with extra libraries. Libraries expand the functionality of a language by adding more functions, APIs (application program interfaces), and features.

NOTE: While learning, try to debug and follow all errors. The error should give line numbers. Check that line, if it leads to another function, check that function. Google the error if that does not help. Replace the file with the original if all else fails.

I will be using many terminal commands. It is dangerous to take the word of a stranger on the Internet when dealing with terminal commands. GNU/Linux has some built in documentation. You will need the Internet to find most information and tutorials, but the built-in documentationation helps as a quick reference. You can use the ''man'' command to look up information about a command. To find information on using the ''ls'' command, try this in a terminal:

man ls

You can also read the manual for the manual with this command:

man man

Python has even more built in documentation than its man page. Open the interactive Python prompt with this command:

python

Now we can access the interactive help menu with this command:

help()

Quit the interactive help menu with this command:

quit

Quit interactive Python with this function:

quit()

You can teach yourself the basics of using the command line with an interactive website at:

https://www.codecademy.com/learn/learn-the-command-line

You can teach yourself the basics of Python with an interactive website at:

http://www.codecademy.com/tracks/python

I highly recommend the codecademy free resources after this workshop. Spend at least 15 minutes each day on codecademy when teaching yourself a new programming language. Codecademy is the easiest way to learn the syntax of a programming language. You can log in to save your progress using Facebook, Google, or make a new account. That is how I started learning Python. When I thought I was familiar enough with the Python syntax to make my own programs, I used google, stackoverflow.com, and other websites to make new programs of my own.

It is about a 13 hour course, but doing 2-4 hours will be enough to get you familiar with the basics of the language and the syntax. You can use google-fu and extra modules to script more after a few hours on codecademy.

Hello, world!

Hello, world! is traditionally the first program that anyone writes when tackling a new programming language. It is a simple program that says, "Hello," to the world.

Relevant XKCD:

NOTICE: This comic is dated and uses the old way to use print. Older versions of Python 2 used this format. Later versions of Python 2 use the new way as well as the old way. It is good to be aware of this, as many old examples still exist on the Internet.

In a terminal, type this command:

python

The cursor will now follow three greater than symbols >>>. Type this command and we will be on our way:

print("Hello, world!")

If you read ''Hello, world!'' back from the computer, you succeeded. Pat yourself on the back and feel good about writing your first line of Python code. Quit interactive Python with this function:

quit()

We will do this same exercise in a different way. Open up a text editor from the terminal using the following command line. Leafpad and nano come installed with Raspbian. Nano is a terminal application so we will use that. We will also create a new file and give it a filename as we open it.

nano hello.py

Write out the print function again.

print("Hello, world!")

Exit by holding CTRL and pressing X. It asks if you want to save changes. Press Y and enter. You have now saved your program as a text file.

We will call this new text file into Python with this quick command:

python hello.py

You wrote your first program! Now, we will get to the good stuff.

hello.py code

Infinite Loops

I believe that infinite loops are one of the most exciting concepts in computer science. A ''normal'' programming book will hold out on this information until much later. I like to give away some spoilers.

We can copy our hello.py file from earlier to a new file with this command:

cp hello.py helloloop.py

We can open the new file with nano using this command:

nano helloloop.py

Now, add a new line to the beginning of the file that reads:

while True:

Put a tab in front of our earlier work so that the file looks like this:

while True:
	print("Hello, world!")

Exit by holding CTRL and pressing X. It asks if you want to save changes. Press Y and enter. You have now saved your program as a text file.

When we run this file, it will not stop printing ''Hello, world!'' until we force the program to close. To close the program, hold CTRL and press C. You could also close the terminal window, but we will need it again in a second. Run the new program with this command:

python helloloop.py

Remember to close it by holding CTRL and pressing C once you have had enough! That was your first loop! Loops are great for when you want to repeat something without having to start it each time. Our loop is much easier to write than the alternative:

print("Hello, world!")
print("Hello, world!")
print("Hello, world!")
print("Hello, world!")
print("Hello, world!")
print("Hello, world!")
print("Hello, world!")
print("Hello, world!")

Programming may seem like a lot of typing at first, but it allows you to type less in the long run.

helloloop.py code

GPIO: General Purpose Input/Output

If you have ever used an Arduino, you are already familiar with input/output pins. These can be programmed and linked to other components to build custom circuits. The Pi A & B have 26 pins. The Pi A+, B+, 2 B, Zero, and 3 B have 40 pins. The Pi Compute Module has 200 pins.

Models A & B Models A+, B+, 2 B, Zero, and 3 B

These are programmable with Python. I will do a simple demonstration of this and continue onward. If circuitry and robotics is a passion of yours, dig in.

I will use two wires and an LED light with two pins, one short and one long. The Pi's third pin from the corner is a GROUND. One wire will connect the LED's short pin to the Pi's GROUND. The other wire will connect the long pin to the pin labeled GPIO7 in the diagram above (the thirteenth pin down on the right).

We will light up the bulb using two methods: once with Python and once with bash. Bash is a command line shell. Getting to know bash is a great way for students to start digging into the most basic elements of programming, so I wanted to introduce it a little bit here.

Setup the modules you will need by running the following on the command line. Modules for Python expand the functionality of the programming language. Some modules are associated with Python by default and many others are available to download. All of your modules can be listed with the Python function ''help('modules')'' from within interactive Python. In this example, we will use the RPIO module, which connects Python with the pins of the Pi, and the time module, which allows Python to track the passage of time.

sudo apt-get update

sudo apt-get install -y python-dev python-rpi.gpio

We will write a Python script using nano again. We will call the file LED7.

nano LED7.py

Once RPIO is installed, this module can be pulled into any Python script with import as shown here.

import RPi.GPIO as GPIO
import time

# Choose which GPIO pin to use
led = 7

# set up GPIO as output
GPIO.setmode(GPIO.BCM)
GPIO.setup(led, GPIO.OUT)

# set pin GPIO7 to be "on," turning on the light
GPIO.output(led, 1)

# delays for 1 second, keeping the light on briefly
time.sleep(1)

# set pin GPIO7 to be "off," turning off the light
GPIO.output(led, 0)

# delays for 1 second, keeping the light off briefly
time.sleep(1)

Exit by holding CTRL and pressing X. It asks if you want to save changes. Press Y and enter. You have now saved your program as a text file.

Since Python is controlling hardware with this script, it will need root privileges. Use this command to run the script:

sudo python3 LED7.py

The light should turn on and off.

Another way to approach this is to use bash. Bash is the default shell for the command line. This is possible because everything in the system is treated like a file, including hardware (like the pins) or other devices. This usage of bash is more complex than the RPIO method in pythod, but it is also very precise. We will not focus on the code here, just be aware that it can be done if students want to manipulate any of the hardware from the command line.

sudo echo "7" > /sys/class/gpio/export

sudo echo "out" > /sys/class/gpio/gpio7/direction

sudo echo "1" > /sys/class/gpio/gpio7/value

sudo echo "0" > /sys/class/gpio/gpio7/value

Echo is a self-explanatory command. It repeats back what you give it. The greater than symbol ''>'' sends the output of the previous command to overwrite a file. In this case, the file is actually hardware instead of a document. This is a unique aspect to Unix and GNU/Linux.

If you replace the LED with a motor, the same code can control a robot!

LED7.py code

LED7withbash.sh code

For more information about projects using the Raspberry Pi's GPIO, check out these links:

Python and pygame

Raspbian comes bundled with some games written in Python. I like to use these games as a starting point when teaching kids about programming in Python. The programs are small enough that you can read them in one sitting, and they are very well commented. Comments are lines that start with ''#'' and are ignored by the computer.

We will pick a game, demonstrate how it works, read code, make a change, and test. This is a great exercise to do with students. However, changing variables is a backwards way to learn a language. Remember to visit codecademy to learn more.

Pygame is a module that can be used to write games and modify them. Python, the pygame module, and games written with pygame can be installed on GNU/Linux, Mac, and Windows. You do not need a Raspberry Pi for this section.

I would suggest downloading Python version 2.7 to maximize compatibility with pygame.

  • GNU/Linux Installation Instructions

Python is probably already installed on your GNU/Linux system. You can check that Python 2.7 is installed by running this command:

python -V

Pygame is installed by default on Raspbian. If you are on a debian based system, you can install pygame with this command:

sudo apt-get update && sudo apt-get install -y python-pygame

Since pygame depends on Python, the correct version of Python would also be installed with this command.

  • Mac Installation Instructions

Download Python and pygame. Install Python and then install pygame. Note: I am purposefully linking to an older release of Python 2.7.

  • Windows Installation Instructions

The easiest way to install Python (and many other common programs) for Windows is through ninite. Ninite is a website that allows you to install many programs at once. The ninite download program can be left on your system and used as an updater in the future.

We also need the pygame module. Install Python and then install pygame.


You can download the code we will start with from:

http://inventwithpython.com/makinggames_src.zip


These games written with pygame originated from the Invent with Python website. You can get a free book that accompanies the games.

There are hundreds of free games that you can modify from the pygame webpage.

Check out the pygame tutorials for more information.

Beginner: Download Al's games from http://inventwithpython.com/makinggames_src.zip Unzip them and play a bit. Then, open a file that ends in .py in a text editor or IDLE, change variables, save it, and test it out by playing the game again.

Intermediate: Change a game from inventwithpython, http://www.pygame.org/, or https://pyweek.org/ into something that looks completely different from the original with different game mechanics. Since you're making bigger changes, save your work with a new file name.

A simple example of this is TheGameThatMarioBeat2.py based on code from wormy.py The Game That Mario Beat 2

Mastery: Build your own game starting with a blank document using python and pygame using the internal documentation for python and pygame and the python and pygame websites.

Photo Editing

To add your own images to games, you need to use a photo editor. GIMP (the GNU Image Manipulation Program) is free and open source and works on the Raspberry Pi 3, GNU/Linux, Mac, and Windows.

The default layout has three windows (tools, image, and layers) and can be confusing to young kids. On the menu bar, choose Window and "Single-Window Mode" to make it easier to navigate.

Beginner: To familiarize yourself with it, take an image from PyGame or Ren'Py and make some changes to it. Export it into the same format and test the python script to make sure it works.

Intermediate: Use a picture from the Internet. If you are planning on using the image for a public project, make sure you have the right to reuse the image. Bring the image into GIMP. In the layers panel, right click on the image layer and choose "Add Alpha Channel" which adds the ability to have a transparent background. Crop the character, sprite, or object so that everything else is a checkerboard pattern. Save it as a png file. Try using this png with python in a pygame activity. You could also take a photo of yourself with a camera, open the photo with GIMP, crop your body or face so that the background is transparent, save the image, and test with python.

Minecraft: Pi Edition

Minecraft is the best selling game of all time. Mojang (the original developer of Minecraft) wrote a version specifically for the Raspberry Pi. Mojang gave it alway for free in hopes of teaching youth programming. Python and java modules accompany the game. Minecraft: Pi Edition and the python and java modules are already installed on Raspbian.

NOTE: Minecraft: Pi Edition only works for the Raspberry Pi's CPU architecture ARM. Since the game itself is not open source, it cannot be recompiled for other computers. To work with Minecraft: Pi Edition on a 32 or 64 bit CPU architecture, you have to emulate a Raspberry Pi with something like QEMU (more on that in the projects section).

Start up Minecraft: Pi Edition.

NOTE: Do not make the game full-screen. Children tend to do this first thing. The mouse will not work optimally, and it is not meant to be full-screen. It is meant to take up some of the screen while you code next to it.

Create a world and start to play. Notice the three cartesian coordinates in the top left corner of the screen. These coordinates give numbers to the x, y, and z axis of the game world.

Open up leafpad to code in a text file, or type ''python'' into the terminal to code in an interactive Python shell, and we will write a program for Minecraft.

# import the modules
from mcpi import block
from mcpi import minecraft

# First make a connection between Python and the game
mc = minecraft.Minecraft.create()

# mc is a object we can call to control the world.  Let's say, ''Hello!''
mc.postToChat("Hello, Minecraft World!")

# Now add a block.  You could read the coordinates in the top left, and choose numbers near those.
mc.setBlock(-7, 10,0 , block.STONE)

# Try to spell a word in the sky.  It is very easy with copy and paste.
mc.setBlock(-7, 9, 0, block.STONE)
mc.setBlock(-7, 8, 0, block.STONE)
mc.setBlock(-7, 7, 0, block.STONE)
mc.setBlock(-7, 6, 0, block.STONE)
mc.setBlock(-7, 9, 1, block.STONE)
mc.setBlock(-7, 10, 2, block.STONE)
mc.setBlock(-7, 9, 3, block.STONE)
mc.setBlock(-7, 10, 4 , block.STONE)
mc.setBlock(-7, 9, 4, block.STONE)
mc.setBlock(-7, 8, 4, block.STONE)
mc.setBlock(-7, 7, 4, block.STONE)
mc.setBlock(-7, 6, 4, block.STONE)
# I spelled the letter M.  Try to write your name and impress your friends.

If you typed this into a file, save it as minecrafthack.py and run it with ''python minecrafthack.py''

Something is not right. We will have to fix it. See if you can fix my capital M.

See if you can write your entire name.

There are other projects that can be found elsewhere like the interactive photo booth, giant clock, and more.

minecrafthack.py code

This is only the beginning of what can be done. Check out these links for more Minecraft projects with the pi.

Looping GPIO with Minecraft

Programming Python, loops, GPIO, and Minecraft is all cool, but can we combine them? Yes. Here are two example scripts:

minecraftlight.py code

minecraftlightloop.py code

Processing

Processing is a great introductory programming language that can make generative art, interactive art, and drawing. https://processing.org/

Processing is a programming language about making visual art. Processing is geared towards making interactive drawings with code. It works on Android, iOS, GNU/Linux, Mac, and Windows. Drawings can be generated from mouse movements, music frequencies, GPIO inputs, or web apis. Processing is one of the easiest languages to learn. Processing uses java syntax by default. You can also use javascript live on webpages through p5.js. Python syntax can also be used if enabled.

To install processing on the Raspberry Pi, run these two commands:

wget https://processing.org/download/install-arm.sh

sudo sh install-arm.sh

If you want to use P3D, this command will fix a bug in the latest versions of Raspbian (at the time of this writing):

sudo aptitude remove libgles1-mesa libgles2-mesa

These are scripts I have made or modified using Processing:

Screenshot

Generative art using randomly moving triangles of random sizes. These triangles have a calming and mesmerizing effect on the viewer. As this script continues, the result becomes more unique and beautiful. Run for an hour to multiple days. Hold 's' to save images.

Screenshot

JitterRotate is an experiment with semantic errors. Generative art using randomly moving triangles of random sizes, colors, rotation, and transparency. This sketch only takes about 30 seconds to peak. Hold 's' to save images.

Screenshot

Draw with squares, ellipses, and triangles. Shapes have random fill color, stroke color, stroke width, and size. WARNING: Contains flashing lights. Hold 's' to save images.

The code for my processing examples can be found at my Processing github.

To learn more, check out the Resources section and my page of examples.

Note: Java is licensed under the Oracle Binary Code License which differs from many of the other licenses discussed around the Raspberry Pi.

Computer Vision: opencv-python and simplecv

I will not demonstrate Computer Vision, but I have to mention it. ''opencv'' allows you to program the sense of sight. Analyze photos, video, or live feeds and make decisions based on what you "see." It is a very powerful module for Python. ''simplecv'' makes it much easier to write programs. OpenCV is a framework that works on top of C++, Java or Python.

To learn more, check out the Resources section.

Taking The Raspberry Pi Further

Programming on the Raspberry Pi is one of my favorite activities, but I understand that not everyone is as passionate about code as I am. There are many different directions you can take with the Raspberry Pi that have nothing to do with code. This section is full of projects, solutions, and resources to use the Raspberry Pi in creative ways.

Projects

  • Raspberry Pirate Radio

Have you ever wanted to run your own radio station? You can turn your Raspberry Pi into an FM radio transmitter using one wire and a Python script.

Notice: If the project was left running in the United States, the FCC could track you down for using improper signals. The problem is that depending on the frequency you use, you could be interfering with frequencies used by emergency services. The reason for this is the makeshift antenna and program sends out block shaped radio waves instead of sine waves. This spills over to other frequencies unintended by the program.

http://www.instructables.com/id/Raspberry-Pirate-Radio/

http://makezine.com/projects/raspberry-pirate-radio/

http://lifehacker.com/start-a-pirate-radio-station-with-a-raspberry-pi-and-a-1538837219

http://myhowtosandprojects.blogspot.com/2014/04/raspberry-pi-make-your-own-pirate-radio.html

  • Build a robot

If you can power a light with GPIO pins, you can just as easily connect it to a motor. Add more motors and you have a robot.

http://diyhacking.com/raspberry-pi-robot/

Make a Raspberry Pi-Controlled Robot: Building a Rover with Python, Linux, Motors, and Sensors By Wolfram Donat

  • Create your own web server

What better way to learn web design than creating your own web server? You can turn a Raspberry Pi into an entire web stack. ''LAMP'' stacks are very popular among the industry (GNU/Linux + Apache + MySQL + PHP). I prefer using smaller programs to accomplish nearly the same thing. I use GNU/Linux + Nginx + SQLite + PHP (LNSP) when using a web stack on the Raspberry Pi. These can also interact with Python.

https://wiki.archlinux.org/index.php/Nginx

  • Universal Translator

This project allows you to convert speech from one spoken language to another. Record audio of talking, convert the audio to text, translate the text to another language, and have it read back to you in another language.

http://www.daveconroy.com/turn-raspberry-pi-translator-speech-recognition-playback-60-languages/

https://github.com/dconroy/PiTranslate

  • Connect Raspberry Pis to automate your home

The ''Internet of Things'' (IoT) is a way to connect everything together through the Internet. Purchasing IoT devices and appliances can be COSTLY unless you do it yourself. A single board computer and a little bit of Python knowledge can start you on the path to creating your own IoT devices. Slap a Raspberry Pi onto a garage door, program it to listen for your phone to connect to the network, and you have an automated garage door. There are unlimited possibilities now with single board computers.

http://www.informationweek.com/software/enterprise-applications/10-raspberry-pi-projects-for-learning-iot/d/d-id/1320757

https://www.raspberrypi.org/blog/tag/internet-of-things/

  • Build your own camera

The Raspberry Pi foundation has designed two camera modules that can be easily connected to the Raspberry Pi. They are the camera and the infrared modules.

RPi Camera Module

RPi Infrared Camera Module

RPi Camera help

  • Emulating a Raspberry Pi on your Computer with QEMU and Windows

Emulating a Raspberry Pi on your Computer with QEMU and Windows

I confirm that it works and covers all pitfalls. It feels very slow to use because it is limited by 256mb of allocated RAM. The advantage of emulating the Pi on a computer is that the img file can be modified directly. A custom img with updated software and all of your programs can then be copied to your SD card.

  • Build a Retro Game system

The RetroPie project aims to turn a Raspberry Pi into a game system. It includes an interface called emulationstation and can emulate many of the game consoles from 1977 to 1998.

To install RetroPie on top of default Raspbian run these commands:

sudo apt-get update
    
git clone git://github.com/petrockblog/RetroPie-Setup
    
cd RetroPie-Setup
    
sudo ./retropie_setup.sh

The games will need to be copied into the appropriate folder before the console will appear in the menu. Logout to the terminal and run this command:

emulationstation

A popular alternative to this project is to build a RetroPie into a handheld case using 3D printed cases and a tiny screen.

Official RetroPie Website

3D printing project for a GameBoy style case

Micro Arcade Cabinet

  • Build your own ''cloud'' server

The term cloud has been confusing the majority of computer users since its creation. It simply means you are putting your private data on someone else's server. Since you cannot verify that their interests are in your best interest, the majority of cloud based services cannot be trusted. You could build your own cloud! I will suggest Freedom Box. It acts as a cloud and more.

FreedomBox Foundation

  • Talk with all of your friends at once

You can run a server on your Raspberry Pi called mumble that will allow your friends to all connect and talk to each other at once.

Mumble Server forum post

  • Design your own case

If you have access to a 3D printer or some spare legos, you can make your own cases. You can use any 3D modeling software to design your own 3D shapes to protect your Raspberry Pi. Here are some examples of cases that others have made:

8 Interesting DIY RPi Case Ideas

Thingiverse 3D models Raspberry Pi Results

  • Try a program out in space

The AstroPi project put some Raspberry Pi computers on the International Space Station. You can build a duplicated device using a 3D printer, a Raspberry Pi, and a Sense Hat. There are programming competitions regularly that you can enter. Your Python experiment can be carried out in space. The Raspberry Pis in space even have their own twitter accounts that you can browse.

https://astro-pi.org/

https://www.raspberrypi.org/blog/astro-pi/

https://twitter.com/astro_pi_ir

https://twitter.com/astro_pi_vis

https://vimeo.com/157627149

  • Control your stereo over wifi

How cool would it be to use your phone to control the stereo? You can do that with the Raspberry Pi. Put all of your music on a storage device. Connect your music collection to your Pi. Install and configure mpd (Music Player Daemon) on your Pi. Connect your Pi to the stereo. Connect your phone to your Pi through an MPD app such as MPoD or MPDroid.

http://elinux.org/Rpi_Music_Player_Daemon

  • Build a media center

Kodi is a powerful media center that can be installed on your Raspberry Pi. You can view your video files from a hard drive or stream files from the web. I have had the most success with OSMC which can be installed directly from NOOBS with an Internet connection.

OSMC

  • Build your own tablet

The Raspberry Pi has released a 7 inch touch screen. Connect the cables to the Pi, add power, and you have a tablet.

https://www.raspberrypi.org/products/raspberry-pi-touch-display/

  • Virtual Network Computing (VNC)

VNC can be used with nearly all computer systems including GNU/Linux, iOS, Mac, and Windows. It is a way to share control of a computer across a network or the Internet. Today, it is most commonly used for tech support from remote sites. VNC software can be installed with these commands:

sudo apt-get install tightvncserver xtightvncviewer

A VNC server can be started with this command:

vncserver :1 -geometry 1920x1080 -depth 24

Other computers or phones on your network can connect to your Raspberry Pi with the proper credentials using your local IP address. IPv4 addresses are four sets of numbers separated by periods. An example of an IP address is 192.168.1.58. Your local IP address can be found using the command:

ifconfig | grep inet

https://www.raspberrypi.org/documentation/remote-access/vnc/

  • Build a surveillance system

Build your own motion detection cameras and have them email you when someone walks near your car. Create a camera that emails you a picture of your desk every hour. The possibilities are endless.

  • What should I wear today?

Create a system to check the temperature and humidity outside. Based on that information, the Raspberry Pi could email you what you should wear to stay warm throughout the year.

  • Create interactive installation art

Many artists have included Raspberry Pis into their work. One of the most tranquil of such projects is called ''Lichen Ohms Seriatim'' located in Cambridge, United Kingdom. Participants carry around a Raspberry Pi with a screen, bluetooth adapter, headphones, and a battery in a clear plastic container. The sounds change as they approach bluetooth beacons referred to as ''lichens.'' This creates an immersive audio/video experience.

https://www.raspberrypi.org/blog/lichen-beacons/

http://www.ludions.com/projects/lichens/

  • Build a supercomputer

You can create a beowulf system by connecting a bunch of computers together using network cables, GNU/Linux, and software to make them act as one.

http://www.zdnet.com/article/build-your-own-supercomputer-out-of-raspberry-pi-boards/

33 Raspberry Pi Cluster

64 Raspberry Pi Cluster

GCHQ's 66 Raspberry Pi Cluster

Pi Zero OTG Cluster

  • Participate with an open source project

Another great way to get more experience is to find a python script on github, make a github account, and fork the project. To fork a project, you can take someone else's program, make changes, and make it your own; or you can make a change, and submit the change back to the original project. Even changing a simple grammar mistake is a great first move.

Problems and Solutions That Worked for Me

This section is not a comprehensive troubleshooter for a Raspberry Pi, but it gives some examples of the problem solving skills that will be beneficial to your journey into microcomputers. When I bought my model B, a lot of problems had not been worked out. Compromises, workarounds, and hacks had to be implemented to accomplish some goals. Many of these problems have been solved with the new line of Raspberry Pis including the A+, B+, 2 B, Zero, and 3 B.

  • Low resolution video

This happens with kids ofen. The quick solution is to reboot. Click on the menu in the top left > Logout > Reboot.

This happens when you first plug in the Raspberry Pi with the power before the HDMI. If you change the order of operations to HDMI and then power, the boot process will automatically identify the video source and give provide optimal resolution.

  • Wireless adapters

Wireless adapters do not always work. Some brands work very well and others require extra work to use them. After doing too much of the extra work, I always look up the chipset of compatible wireless cards BEFORE I buy a new one. Atheros chipsets are nearly always compatible. The packaging rarely says the name of the chipset so you always have to look it up.

  • Peripheral power / Powered USB Hub

The B has two USB ports. I need to plug in a keyboard, a mouse, and a wifi adapter. I could plug in the keyboard and mouse at the same time and use it perfectly with a wired ethernet connection. I could unplug the keyboard, plug in the wifi, search for networks. To enter in a password, I would have to unplug the mouse, plug the keyboard in, type the password, and then plug in the mouse. Just after I got a valid IP address, the wifi adpater would lose power. It would start up again, connect, and lose power. This loop would continue until I unplugged it. I ordered a powered USB hub off amazon. Once that arrived, I could plug in a keyboard, mouse, wifi adapter, and two storage devices. The best part about the powered USB hub is that you can power the Raspberry Pi with a MicroUSB to USB cable. The drawback after this is that I was using much more power then before. I was very surprised when I tried the B+ with four USB slots. On the B+, I plugged in keyboard, mouse, and wifi directly in and it worked perfectly.

  • Corrupted SD Cards

The operating system traditionally uses either a SD card or a microSD card. The firmware of the first production run ruined many SD cards. The firmware can be updated and it eventually got better. I had been running various GNU/Linux operating systems off of 16GB flash drives for many years at this point. After corrupting the same SD card many times, I gave up on the SD card. I had to use it to boot from, but I did not have to run the system off of it. Default Raspbian has two partitions in its .img file. One is a boot and the other is the root. I modified the boot configuration to boot from /dev/sdb2 instead of /dev/sda2. I then used dd to copy the Raspbian img to a flash drive. That one still works.

  • Audio pops

One of the projects I made turned my Raspberry Pi model B into an mp3 player for my hi-fi stereo. I could control it with my iPhone over the network. Everything talked perfectly together. The only problem I had was that there would be a loud pop between each track. Not only is this annoying, but it could damage my speakers. The problem was well known on the Internet and by the developers. The problem was that the power would turn off when not in use and then turn back on. The power could not be left on using ALSA the default audio interface on Raspbian. I solved this problem by installing PulseAudio. I configured pulse to remain always on. This solved my problem. The Raspberry Pi B+ and 2 B fixed this problem.

  • No HDMI Video Output

I did a programming workshop using my model B. I introduced what we were doing on a TV with the Pi. Later that day, I took it back out and I could not get any output from the HDMI. After troubleshooting a few things, it went back in the bag. I later give it to my tech team to try to solve the problem. They researched ways to troubleshoot the HDMI, they took off the case, and got it to work. This was reproducible. That official case has since been replaced with legos.

  • Wireless Drivers

Wireless adapters do not always work. This is because the hardware manufacturer has closed source, proprietary drivers. Some brands work very well and others require extra work to use them. After doing too much of the extra work, I always look up the chipset of compatible wireless cards BEFORE I buy a new one. Atheros chipsets are nearly always compatible. The packaging rarely says the name of the chipset so you always have to look it up.

  • No hardware clock

Desktop computers typically have a coin sized battery attached to the motherboard to keep the clock running on the BIOS. When the Rapsberry Pi gets turned off, it loses track of time. When connected to the Internet, this should not matter as it will get the correct time from a server. For offline projects, you must keep this in mind if your program uses specified times. As a work around, I boot up the system, set the time manually, reboot, and then the clock is correct. An example of this code is:

sudo date -s "14 APR 2053 15:34:00"

Raspberry Pi Giveaway

We will pick an almost random number using Python. Everyone gets a number 0 - n.

from random import randint

n = 30 # 31 participants because 0 is a number.

print(randint(0,n))

The winner gets a Raspberry Pi!

If you did not win, you can buy the one I did this presentation with at cost.

Encode QR Code

We can encode a QR code offline on the Raspberry Pi using qrencode.

To install qrencode on the pi run this command:

sudo apt-get update && sudo apt-get install -y qrencode

We will encode a QR code of this website to a PNG and then display the QR code with these two commands:

qrencode -o qrcode.png 'https://github.com/TechnologyClassroom/RaspberryPiProgrammingWorkshop'

feh -F qrcode.png

For more ideas on using qrencode, check out this Linux Magazine link.

Resources

This section contains websites and books for everything you ever wanted to know about the Raspberry Pi, GNU/Linux, Python, Processing, and Computer Vision.

Raspberry Pi Links:

Raspberry Pi Books:

Python and Programming Links:

Python Books:

Processing Links:

Processing Books and videos for purchase:

Computer Vision Links:

Computer Vision Books:



This guide was made with a laptop running GNU/Linux, various Raspberry Pi models, and countless hours of volunteer work and tinkering from open source programmers.

Python is one of the most fun programming languages. Remember to have fun with it and follow your imagination.

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