Pullup resistors for input GPIO pins

[alanchrt]

I'm having some difficulty getting the pullup resistor functionality to work on a security system I'm building for my home.

Here's the code:

from bbio import *
from EventIO import *

# Define delay times
TRIGGER_TIME = 30 # seconds
DEPART_TIME = 30 # seconds

# Define pin locations
BEEP_PIN = PWM1A
ARM_PIN = GPIO1_28
DISARM_PIN = GPIO0_7
FRONT_DOOR_PIN = GPIO2_12
SIDE_DOOR_PIN = GPIO2_13
BACK_DOOR_PIN = GPIO2_8
MOTION_SENSOR_PIN = GPIO2_9

class SecuritySystem(object):
    """The security system core."""
    def __init__(self):
        # Setup the event loop
        self.event_loop = EventLoop()

    def arm_button(self):
        # The arm button was pressed
        print "arm button"

    def disarm_button(self):
        # The disarm button was pressed
        print "disarm button"

    def setup(self):
        # Initialize IO pins
        pinMode(ARM_PIN, INPUT, 1)
        pinMode(DISARM_PIN, INPUT, 1)
        pinMode(FRONT_DOOR_PIN, INPUT, 1)
        pinMode(SIDE_DOOR_PIN, INPUT, 1)
        pinMode(BACK_DOOR_PIN, INPUT, 1)
        pinMode(MOTION_SENSOR_PIN, INPUT, 1)

        # Attach events
        self.event_loop.add_event(DigitalTrigger(ARM_PIN, LOW, self.arm_button, 300))
        self.event_loop.add_event(DigitalTrigger(DISARM_PIN, LOW, self.disarm_button, 300))

        # Start the event loop
        self.event_loop.start()

    def loop(self):
        # Print out ARM_PIN state
        print digitalRead(ARM_PIN)

ss = SecuritySystem()
run(ss.setup, ss.loop)

Even thought I have pull=1 for the pinMode, I still always get LOW values for the state of the pins. I can substitute any of the other pins for ARM_PIN in the loop with the same result.

I'm using an Ubuntu image (http://elinux.org/BeagleBoardUbuntu#Precise_12.04_armhf) and have successfully used the pullup resistors on this bone before with bonescript on Angstrom.

Any idea what could be preventing the pullup resistors from activating?

[alexanderhiam]

Thanks Alan. The issue was that when the DigitalTrigger initializes it call pinMode() on the trigger pin, but I had forgotten to allow for configuring pullup/pulldown resistors. Just fixed it and pushed the changes. Update PyBBIO then just add the pull arg where you're creating the DigitalTriggers like this:

  DigitalTrigger(ARM_PIN, LOW, self.arm_button, 300, pull=1)

This means you can also leave out the calls to pinMode() for those pins.

[alanchrt]

Awesome, this is perfect!