IOError: [Errno 2] No such file or directory: '/sys/devices/virtual/gpio/gpio25/value'

[nick-hills]

Running this stripped down test code, the subject error occurs.

!/usr/bin/python

import pifacecommon.core
import pifacecommon.interrupts
import os
import time

def print_flag(event):
print ("You pressed button" + event.pin_num)

pifacecommon.core.init()
port = pifacecommon.core.GPIOB
listener = pifacecommon.interrupts.PortEventListener(port)

listener.register(0, pifacecommon.interrupts.IODIR_ON, print_flag)

listener.activate()

results in:

Process Process-1:
Traceback (most recent call last):
File "/usr/lib/python3.2/multiprocessing/process.py", line 267, in _bootstrap
self.run()
File "/usr/lib/python3.2/multiprocessing/process.py", line 116, in run
self._target(_self._args, *_self._kwargs)
File "/usr/lib/python3/dist-packages/pifacecommon/interrupts.py", line 207, in watch_port_events
gpio25 = open(GPIO_INTERRUPT_DEVICE_VALUE, 'r') # change to use 'with'?
IOError: [Errno 2] No such file or directory: '/sys/devices/virtual/gpio/gpio25/value'

[tompreston]

You need to enable interrupts first when using just pifacecommon. I appreciate that this probably needs better documentation, I did not realise so many people were using it. Also be careful, the function enable_interrupts() is scheduled to change in the next version of pifacecommon v4.0.0. Make sure you read the change log.

#!/usr/bin/python

import pifacecommon.core
import pifacecommon.interrupts
import os
import time

def print_flag(event):
    print ("You pressed button" + event.pin_num)

pifacecommon.core.init()
port = pifacecommon.core.GPIOB

pifacecommon.interrupts.enable_interrupts()

listener = pifacecommon.interrupts.PortEventListener(port)

listener.register(0, pifacecommon.interrupts.IODIR_ON, print_flag)

listener.activate()