After several maddening errors it occurs to me that there is a problem in my GPIO setup, to wit, RPi.GPIO is failing silently.
To test this theory I got my multimeter, set it to volts, put one probe in ground and another probe in the GPIO port (GPIO 17 in this case) and get 0 volts coming through.
Ordinarily I would think there is a loose conection, or a problem with the board (I am using the Adafruit T-Cobbler http://www.adafruit.com/products/1105 ) but I am able to move a servo with this command (using servoblaster) (which does not use the RPi.GPIO library)
echo p1-22=50 > /dev/servoblaster
My question is - am I testing the GPIO correctly? Is there a better way to test if I am getting any current through the GPIO setup?
The code I am using (Python) is as follows
import RPi.GPIO as GPIO import time GPIO.setmode(GPIO.BCM) dirPin = 4 stepPin = 17 GPIO.setup(dirPin, GPIO.OUT) GPIO.setup(stepPin, GPIO.OUT) for i in range(0, 3): GPIO.output(dirPin, 1) GPIO.output(stepPin, 1) time.sleep(15000) GPIO.output(dirPin, 1) GPIO.output(stepPin, 0) time.sleep(10)