When you put together one of our interface boards you’ll see that it breaks out the GPIO pins into their own header and labels them 0 to 7. Our GPIO library numbered Pins 0..23, after the header pins on the Raspberry Pi. That’s pretty awkward in practice so we’re experimenting with ways to make it easier to write programs that work with broken out GPIO headers.
Our current approach is to replace the Pin type with two pin classes: GPIOPIn and HeaderPin. A GPIOPin is created with a pin number from 0 to 7 that identifies the pin on the interface board. A HeaderPin is created with a pin number from 0 to 23 that identifies the pin on the Pi’s header.
For example:
#!/usr/bin/python3
import sys
from time import sleep
from quick2wire.gpio import GPIOPin, In, Out
led = GPIOPin(1, direction=Out)
button = GPIOPin(0, direction=In)
while True:
led.value = button.value
sleep(0.1)
To ensure that existing code keeps working, we define Pin as a synonym of HeaderPin. But when we’ve found an approach that works well we’ll deprecate Pin and eventually remove it from the API.