Hands on Raspberry Pi

Connect your Pi

- Raspberry Pi 2- Micro SD card- HDMI cable- HDMIPi screen & power cable- Mouse- Keyboard- WiFi dongle- Raspberry Pi power cable (last)

Log in

Username: piPassword: raspberry

Note: Password will not show while typing

Try the command line

Type the commands:- ls- ls -l- pwd- cd python_games- ls- cd

Boot to desktop

- Run the command startx- Hit Enter

Open Python 3

Python is a programming languageIDLE is a Python application

Hello world

In the IDLE Python window, enter:

print(“Hello world”)

and hit Enter

Calculator

Try:

2 + 210 * 5123 + 456

Variables

Try:

a = 1b = 2c = a + bprint(c)

Strings

Try:

name = “Ben”print(“Hello ” + name)

Syntax errors

Try:

print(Hello)print(“Hello)print(“Hello’)

Types

Try:

age = 26“My age is ” + age

Type casting

Try:

“My age is ” + str(age)

Loops

Try:

for i in range(10): print(“Hello”)

Loops

Try:

for i in range(10): print(i)

Exit IDLE

Close the IDLE window

GPIO pins

GPIO pins

Breadboard

Connect ground rail

Wire up LED to 3V3

Open Terminal

Create new folder

Type mkdir intro and hit Enter

This creates a new directory (folder) called intro

Enter the folder

Type cd intro and hit Enter

“Change directory intro”

This enters the directory intro

Open IDLE as super user

In the Terminal window, run:

sudo idle3 &

This will open IDLE with super user permissions - we need this to access GPIO pinsThe ampersand (&) opens it in a new process

Open a new window

Go to File > New window

Save file

Go to File > Save

Save as led.py in your intro folder

Flashing LED programfrom RPi import GPIO

from time import sleep

GPIO.setmode(GPIO.BCM)

GPIO.setwarnings(False)

GPIO.setup(2, GPIO.OUT, False)

for i in range(10):

GPIO.output(2, True)

sleep(0.1)

GPIO.output(2, False)

sleep(0.1)

Move from 3V3 to GPIO 2

Run the script!

Press F5 to run the program

Add second LED

New file

Go to File > New windowSave as led2.py

Code for 2 LEDsfrom RPi import GPIO

from time import sleep

GPIO.setmode(GPIO.BCM)

GPIO.setwarnings(False)

red = 2

blue = 3

GPIO.setup(red, GPIO.OUT, False)

GPIO.setup(blue, GPIO.OUT, False)

Flash continuouslywhile True:

GPIO.output(red, True)

sleep(0.1)

GPIO.output(blue, True)

sleep(0.1)

GPIO.output(red, False)

sleep(0.1)

GPIO.output(blue, False)

sleep(0.1)

Make it stop!

Press Ctrl + C to force quit (it won’t ever end)

Shut down your Pi

Enter sudo halt in the Terminal

OR

Shut down from the main Menu

Connect your Camera

Boot the Pi and log in

Test the camera

Type raspistill -k and hit Enter

This starts the camera preview

Hit Ctrl + C to stop

Take a selfie!

Type raspistill -o image.jpg and hit Enter

raspistill is the command for using the camera-o means “output”image.jpg is the chosen filename

Check the photo is there

Run ls to see the photo is thereRun startx to boot to Desktop

Open File Manager

Open image

Double click image.jpg to view it

Open IDLE as root

Open TerminalOpen IDLE as root user

sudo idle3 &

New file

Go to File > New windowSave as camera.py

Take a selfie with Pythonfrom picamera import PiCamera

from time import sleep

with PiCamera() as camera:

camera.start_preview()

sleep(5)

camera.capture('/home/pi/image2.jpg')

camera.stop_preview()

View the photo from File ManagerNotice the difference in resolution between the file taken from the command line and from Python

This is due to default settings in raspistill and in Python picamera

Resolution and other aspects are configurable

Connect a GPIO push button

Add the button to the codefrom picamera import PiCamera

from time import sleep

from RPi import GPIO

button = 17

GPIO.setmode(GPIO.BCM)

GPIO.setup(button, GPIO.IN, GPIO.PUD_UP)

with PiCamera() as camera:

camera.start_preview()

GPIO.wait_for_edge(button, GPIO.FALLING)

camera.capture('/home/pi/image3.jpg')

camera.stop_preview()

Press the button to take a picture

Run the script with F5Wait for the previewPress the push button to take a picture

View the photo from File Manager

Add a loopwith PiCamera() as camera:

camera.start_preview()

GPIO.wait_for_edge(button, GPIO.FALLING)

for i in range(5):

sleep(3)

camera.capture('/home/pi/image%s.jpg' % i)

camera.stop_preview()

What’s the difference?GPIO.wait_for_edge(button, GPIO.FALLING)

for i in range(5):

sleep(3)

camera.capture('/home/pi/image%s.jpg' % i)

camera.stop_preview()

for i in range(5):

GPIO.wait_for_edge(button, GPIO.FALLING)

sleep(3)

camera.capture('/home/pi/image%s.jpg' % i)

camera.stop_preview()

What can you do?

Raspberry Pi Resources

Raspberry Pi Camera Resources

Experiment time!

- Try combining buttons, LEDs, camera- Different buttons for different actions- 2 buttons to start/stop preview- LED status- What else is in your CamJam kit?- Use your imagination!

Updating your SD Card

(you must be online)

sudo apt-get updatesudo apt-get upgrade

Installing software

sudo apt-get install tree

sudo pip install twython

sudo pip-3.2 install twython