Home page 1

Raspberry Pi

A simple start

Hope this helps someone

I wanted to understand programming the raspberry Pi using Python to control the RPIO outputs.

I did not want to buy extra boards or download other peoples written programmes.

************

My main intitial problem was understanding that the GPIO library is not installed in IDLE 3

and that you cannot just work in python and expect the GPIO control pin bit to work - you have to use sudo to run a programme.

Open up IDLE .........Not IDLE 3
Under File - New Window
Write your programme in the new window
e.g.
import RPi.GPIO as GPIO
import time
GPIO.setmode(GPIO.BOARD) ...... sets to pin number - for GPIO number change BOARD to BCM
GPIO.setup(11, GPIO.OUT) .....Note I connected my light/resistor to pin 11 or GPIO 17
GPIO.output(11,True) .......Turns light on
time.sleep(2) ..........wait a couple of seconds
GPIO.output(11,False) ..........Turns light off

Save the file as an example lights1

To run it click on the start button - bottom left
click on run and type
sudo python lights1.py ..... for lights1 put your saved name
IF you save it in a folder e.g. Python
then type
sudo python Python/lights1.py

I butchered a printer cable - which fits on the GPIO pins of the Pi and soldered on some pins at the other end - these fit into a standard breadboard

I bought some led's and resistors as well as wires to use as jump wires with the breadboard.

first setup

yellow wire from Pin 6 or Ground to one end of the resistor

white lead from pin 11 or GPIO 17 to long leg on the LED

Short leg of LED to resistor.

***********

I then wanted to enter a number so that I could tell it how long to put the light on.

from Tkinter import *
root = Tk()
root.withdraw()
import tkSimpleDialog
number = tkSimpleDialog.askinteger("Integer", "Enter a Number")
print (number)

this little programme pops up a box asking for a number - which is then put into the variable number

also prints it out just to check

************

Now substitute number instead of the 2 and it asks for a number - you input it - and then it lights the light for that length of time.

Open up IDLE .........Not IDLE 3
Under File - New Window
Write your programme in the new window
e.g.
import RPi.GPIO as GPIO
import time

from Tkinter import *
root = Tk()
root.withdraw()
import tkSimpleDialog
number = tkSimpleDialog.askinteger("Integer", "Enter a Number")
print (number)
GPIO.setmode(GPIO.BOARD)
GPIO.setup(11, GPIO.OUT)
GPIO.output(11,True)
time.sleep(number)
GPIO.output(11,False)

My programme is named lights1 and is in a folder called Python

so to run it Save the file

To run it click on the start button - bottom left
click on run and type
sudo python Python/lights1.py

************

Any comments to

brian @ ftfarm.co.uk

remove spaces either side of @ - left to stop robots getting my email.