- added README.md

- added systemd service descriptors
- new features in gpio_trigger.py:
  - support waiting for a hold period (-H)
  - added option to ignore command's result code (-i)
  - added variable subtitution in the arguments (%PIN% and %STATE%)

gpio_trigger.py

@@ -1,7 +1,7 @@
 #! /usr/bin/env python
 
 #
-# gpio_trigger.py - execute a command when a GPIO pin is triggered (up or down)
+# gpio_trigger.py - execute a command when a GPIO input pin changes
 #
 # Version 1.0, latest version, documentation and bugtracker available at:
 #		https://gitlab.lindenaar.net/scripts/raspberrypi
@@ -24,8 +24,12 @@ from os import fork, system
 from argparse import ArgumentParser
 from RPi import GPIO
 
-parser = ArgumentParser(description='Run command when a Raspberry Pi pin is'
-                                    ' high or low (e.g. a button is pressed)')
+parser = ArgumentParser(
+    description='Run command when a Raspberry Pi pin changes to high or low.',
+    epilog='(*) use \'--\' to stop argument parsing, arguments can contain the '
+           'following variables: %PIN%=pin number, %STATE%=value (HIGH or LOW)')
+parser.add_argument('-D', '--daemon',  action='store_true',
+                    help='run in background (as daemon)')
 pgroup = parser.add_mutually_exclusive_group(required=False)
 pgroup.add_argument('-P', '--pcb', action='store_const', dest='mode',
                     const=GPIO.BOARD, default=GPIO.BOARD,
@@ -50,22 +54,22 @@ pgroup.add_argument('-r', '--edge-rising', action='store_const', dest='edge',
                     const=GPIO.RISING, help='respond to pin going up')
 pgroup.add_argument('-a', '--edge-any', action='store_const', const=GPIO.BOTH,
                     dest='edge', help='respond to any pin change')
-parser.add_argument('-i', '--ignore-result', action='store_true', default=False,
-                    help='ignore command result code (default: exit if <> 0)')
 parser.add_argument('-b', '--debounce',  type=int, default=200,
                     help='debounce period (in milliseconds, default=200)')
+parser.add_argument('-H', '--hold',  type=int, default=-1,
+                    help='optional hold time, pin must be held stable for the '
+                    'specified time in milliseconds to trigger cmd')
 parser.add_argument('-t', '--timeout',  type=int, default=-1,
                     help='optional timeout (in milliseconds) to wait')
+parser.add_argument('-i', '--ignore-result', action='store_true', default=False,
+                    help='ignore command result code (default: exit if <> 0)')
 pgroup = parser.add_mutually_exclusive_group(required=False)
 pgroup.add_argument('-c', '--continuous', default=False, action='store_true',
                     help='continously monitor GPIO pin and run cmd upon change')
 pgroup.add_argument('-o', '--once', action='store_false', dest='continuous',
                     help='monitor pin and run cmd once, then exit (default)')
-parser.add_argument('-D', '--daemon',  action='store_true',
-                    help='run in background (as daemon)')
 parser.add_argument('cmd', help='command to execute when pin goes low')
-parser.add_argument('arg', nargs='*', help='argument(s) for the command, use --'
-                        ' before first argument to stop parsing parameters')
+parser.add_argument('arg', nargs='*', help='argument(s) for the command (*)')
 
 args = parser.parse_args()                              # parse command line
 GPIO.setmode(args.mode)                                 # set GPIO number mode
@@ -76,12 +80,21 @@ if args.daemon and fork() != 0:                         # Fork for daemon mode
 
 ret = 0
 while args.ignore_result or ret == 0:
+    # wait for GPIO pin to be changed in the right direction
     if GPIO.wait_for_edge(args.pin, args.edge, bouncetime=args.debounce,
                                                         timeout=args.timeout):
-        ret = system(' '.join([ args.cmd ] + args.arg)) # run the command
-        if not args.continuous:                         # exit if running once
-            break
+        state = GPIO.input(args.pin)
+        # pin changed, if required check if it is stays the same long enough
+        if (args.hold < 0) or (
+            GPIO.wait_for_edge(args.pin, GPIO.BOTH, bouncetime=args.debounce,
+                                    timeout=args.hold - args.debounce) is None):
+            ret = system(' '.join([ args.cmd ] + [
+                [ 'LOW', 'HIGH' ][state] if arg == '%STATE%' else
+                str(args.pin) if arg == '%PIN%' else arg for arg in args.arg]))
+            if not args.continuous:                     # exit if running once
+                break
     else:                                               # exit if timeout
+        ret = -1
         break
 
 GPIO.cleanup(args.pin)                                  # cleanup GPIO