Now let's add a green LED adjacent to the red one and connect it to GPIO25 (pin 22).

Now create a new file called ledtest2.py and enter the following:

import RPi.GPIO as GPIOimport time# Set up GPIO25 (pin 22) as outputGPIO.setup(22, GPIO.OUT)while 1:  # Turn green LED on  GPIO.output(22, False)  time.sleep(1)  # Turn green LED off  GPIO.output(22, True)  time.sleep(1)

Run the program as root.

pi@raspberrypi ~$ sudo python ledtest2.py

If all goes well, the green LED will flash on and off. Quit the program by hitting CTRL-C.

Now let's get a little more complicated. Create a new file called ledtest3.py and enter the following:

import RPi.GPIO as GPIOimport time# Set up pins 18 (GPIO24) and 22 (GPIO25) as outputGPIO.setup(18, GPIO.OUT)GPIO.setup(22, GPIO.OUT)while 1:  GPIO.output(18, False)   # Turn red LED on  GPIO.output(22, True)    # Turn green LED off  time.sleep(1)  GPIO.output(18, True)    # Turn red LED off  GPIO.output(22, False)   # Turn green LED on  time.sleep(1)

Run the program.

pi@raspberrypi ~$ sudo python ledtest3.py

The LEDs should now flash between red and green.