Raspberry Pi Jam “Chaos Car!”

Raspberry Pi 1
+ battery pack
+ Bluetooth USB dongle
+ i-racer bluetooth car
+ Raspberry Pi camera
+ some Python code
+ loads of sellotape

Chaos car!

Here’s the code:

#!/usr/bin/env python2

import os
import random
import bluetooth
import sys
import time

car_name = "DaguCar"

def find_car_mac( car_name ):
    ret = None

    print "Scanning for a device called %s..." % car_name

    devices = bluetooth.discover_devices()

    for addr in devices:
        dev_name = bluetooth.lookup_name( addr )
        if dev_name == car_name:
            print "Car found!  (MAC=%s)" % addr
            time.sleep( 1 )
            return addr
            print "Skipping device named '%s'." % dev_name

    sys.stderr.write( "Couldn't find a device called %s!\n" % car_name )
    sys.exit( 1 )

#car_mac = find_car_mac( car_name )

print "Using hard-coded MAC address"
car_mac = "20:13:04:23:05:71"

print "Connecting to the car at %s..." % car_mac

sock = bluetooth.BluetoothSocket( bluetooth.RFCOMM )
sock.connect( ( car_mac, 1 ) )

class Car:
    def turn_right(self):
        print("looking right")
        sock.send( '\x6A' )
    def turn_left(self):
        print("looking left")
        sock.send( '\x5A' )
    def roll_forward(self):
        print("watch out in front coming forward")
        sock.send( '\x1A' )
    def roll_backward(self):
        print("beep beep going backward")
        sock.send( '\x2A' )
    def wait(self):
        sock.send( '\x00' )

car = Car()

instruction = ["turn right", "turn left", "roll forward", "roll backward", "wait"]

while True:
    ci = random.choice(instruction)
    if ci == "turn right":
    elif ci == "turn left":
    elif ci == "roll forward":
    elif ci == "roll backward":
    elif ci == "wait":

Improving the code to avoid bumping into walls is left as an exercise for the reader.

Which Raspberry Pi photo was funniest?

We had a great day at the Egham Raspberry Pi Jam, and Rabbit Escape and our Photo Booth:

seemed to go down well:

But which photo was funniest? Here are some of the entries (I had to choose kids’ ones without faces to go on here, but there were some other great ones!):

But the winner has to be the eyeball wearing a hat!

Thanks everyone, see you next time!

Raspberry Pi Funniest Photo Game

For our latest Egham Raspberry Pi Jam, we worked on a photo booth program, using the Raspberry Pi camera. Here’s how we did it.

Downloads: funniest-photo-game.odp, photo-booth.zip.

Update 1: fixed a bug where it tried to create a directory that already exists

Update 2: see the winning photo!


What we did

  • Made and decorated a box that held the Pi and camera steady for taking photos:
    Decorated Box for Raspberry Pi
    (Note the holes for the wires!)
  • Created some costumes (see “Costumes” below)
  • Wrote a Python program (see “Program” below) to display pictures on top of the camera picture, and take photos
  • Wrote up the instructions and competition rules


We made lots of costumes that show up over the picture. They all needed to be 1280×720 pixels, PNG files that use Indexed Color mode. (In Gimp we clicked “Image”, then “Mode”, then “Indexed Color” before choosing “File” then “Export” or “Overwrite” to save them as .png files.)

Here are some examples:

Once we’d made the costumes we put them in a directory called “costumes” next to the program file, photo-booth.py.


To get the Pi ready to run our program we needed to type these commands:

sudo apt-get update
sudo apt-get install python-picamera
sudo apt-get install python-imaging

Once we’d done this, we created the Python program and directories described in the next section, and then we ran the program with:

python photo-booth.py


We made a directory to hold our program on the Desktop of our Raspberry Pi, which we called “photo-booth”. Inside that, we made a “costumes” directory containing our costumes, and a “gallery” directory to hold the saved photos. Also inside “photo-booth” we saved this code as “photo-booth.py”:

import io
import picamera
from PIL import Image
import time
import pygame
import subprocess
import os

class PhotoBooth:
    def __init__( self, camera ):
        self.camera = camera
        self.costumes = os.listdir( 'costumes' )
        self.current_overlay = None
        self.cos_num= 0
        self.current_costume = None



    def set_up_camera(self):
        self.camera.resolution = ( 1280, 720 )
        self.camera.framerate = 24

    def change_costume(self, change):
        self.cos_num += change
        self.cos_num = self.cos_num%len(self.costumes)
        self.current_costume = Image.open( 'costumes/'+self.costumes[self.cos_num])
        self.overlay(self.current_costume, 128)

    def overlay(self, image, alpha):
        pad = Image.new('RGB', (
            ((image.size[0] + 31) // 32) * 32,
            ((image.size[1] + 15) // 16) * 16,
        pad.paste(image, (0, 0))

        if self.current_overlay is not None:

        self.current_overlay = camera.add_overlay(pad.tostring(), size=image.size)
        self.current_overlay.alpha = alpha
        self.current_overlay.layer = 3

    def take_photo(self):
        stream = io.BytesIO()
        camera.capture( stream, format='jpeg' )
        stream.seek( 0 )
        captimg = Image.open( stream )
        imgrgba = self.current_costume.convert("RGBA")
        captimg.paste( imgrgba, ( 0, -100 ), imgrgba )
        self.overlay(captimg, 255)
        captimg.save( 'gallery/photo%d.png' % time.time().real )
        self.overlay(self.current_costume, 128)

    def run(self):
            while True:
                for event in pygame.event.get():
                    if event.type == pygame.QUIT:
                    if event.type == pygame.KEYDOWN:
                        if event.key == pygame.K_LEFT:
                        if event.key == pygame.K_RIGHT:
                        if event.key == pygame.K_SPACE:
                        if event.key == pygame.K_ESCAPE:
                        if event.key == pygame.K_g:
                            subprocess.call('ls gallery/*.png | head -1 | xargs xdg-open', shell = True)
                    if event.type == pygame.MOUSEBUTTONDOWN:

if not os.path.exists( 'gallery' ):
    os.makedirs( 'gallery' )

with picamera.PiCamera() as camera:
    booth = PhotoBooth( camera )

Download code and costumes

You can download the code and costumes we used here: photo-booth.zip.

If you have any questions, feel free to leave a comment below!

Snowflake Christmas card web page on the Raspberry Pi

In this video I will show you how to make an electronic Christmas card for your friends or family using HTML and JavaScript, which means it will be a little web site that anyone can see by going to it in their Internet browser.

I’m doing this on the Raspberry Pi, but you can do the same thing on almost any computer that exists. All you need is a web browser (like Firefox or Internet Explorer) and a text editor (like Notepad or Gedit).

If this looks very difficult, try the video I made making a similar card using Scratch, which is a lot easier: Snowflake Christmas card in Scratch on the Raspberry Pi.

If you’d like to use the snowflake picture I drew, right-click this link and choose “Save link as…” or similar: snowflake.svg.

If you’d like to compare my code against yours, right-click this link and choose “Save link as…” or similar: snowflakes.html.

If you’d like to see what the finished product looks like, just left-click on snowflakes.html above, instead of right-clicking.

Snowflake Christmas card in Scratch on the Raspberry Pi

In this video I will show you how to make an electronic Christmas card for your friends or family using Scratch.

Scratch can work on most computers – you can download it from http://scratch.mit.edu/.

Scratch is already installed on your Raspberry Pi if you’ve got Raspian or NOOBs on your SD card.

(If you want to get a Pi try my Raspberry Pi: Before we start video.)

If you want to try something more advanced, you can make a similar card as a web page: Snowflake Christmas card web page on the Raspberry Pi.