Blink

Now that we have our transistor driving the LED at its full current from GPIO0_30 (P9.11), let's use Adafruit_BBIO to write a program that blinks it at a fixed interval. The first step is to load the universal-io Device Tree overlay as described previously:

# echo cape-universaln > /sys/devices/bone_capemgr.*/slots

Next you'll need to use the config-pin command to manually configure the pin as a digital output:

# config-pin P9_11 in

Now that the pin is configured properly, open a new file in Cloud9 called blink.py with the following code:

from Adafruit_BBIO import GPIO
import time

LED_PIN = "GPIO0_30"
GPIO.setup(LED_PIN, GPIO.OUT)

while True:
  GPIO.output(LED_PIN, GPIO.HIGH)
  time.sleep(0.5)
  GPIO.output(LED_PIN, GPIO.LOW)
  time.sleep(0.5)

Press Run and you should see the LED turn on for half a second, turn off for half a second, and repeat forever. Alright! When you're done watching the light show you can press the Stop button or hit Ctrl + C in the terminal that opened when...