- 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%)

README.md

@@ -0,0 +1,110 @@
+Raspberry Pi Scripts
+====================
+This repository contains my collection of scripts and other snippets for the
+[Raspberry Pi](https://www.raspberrypi.org). I am publishing these in case they
+are of any benefit to other enthusiasts. Use them freely and please let me know
+in case you encounter any issues or require changes.
+
+The latest versions, documentation and bugtracker available on my
+[GitLab instance](https://gitlab.lindenaar.net/scripts/raspberrypi)
+
+Copyright (c) 2019 Frederik Lindenaar. free for distribution under
+the GNU General Public License, see [below](#license)
+
+Contents
+========
+This repository contains the following scripts:
+  * [gpio_trigger.py](#gpio_trigger)
+    is s script to execute a command when a GPIO input pin changes
+  * [rpi_no_hdmi.service](#services)
+    is a systemd service to disable the Raspberry Pi's HDMI port at boot
+  * [rpi_no_usb.service](#services)
+    is a systemd service to disable the Raspberry Pi's USB bus at boot
+  * [rpi_no_wifi.service](#services)
+    is a systemd service to disable on-board WiFi on Raspberry Pi at boot
+  * [rpi_poweroff_button.service](#services)
+    is a systemd service to support a power-off button using [gpio_trigger.py](#gpio_trigger)
+
+
+<a name=gpio_trigger>gpio_trigger.py</a>
+----------------------------------------
+This script was initially written to add a power-off button to a Raspberry Pi,
+[see this blog post](https://frederik.lindenaar.nl/2019/10/23/raspberry-pi-power-off-button.html)
+for the rationale behind it and how to construct and connect a physical button.
+
+The script itself is a generic solution to monitor a GPIO pin and executes a
+command when the input signal on a pin changes. It can run as interactively as
+well as in the background and executes a command once or continuously upon any
+change or specific transition (e.g. HIGH to LOW).
+
+The script is written in Python 2 and uses the `RPi.GPIO` library as both are
+installed by default on most distributions so should just work. Please note that
+by default the script should be started as root to gain access to the GPIO port.
+
+To implement a simple power-off button, install the script in `/usr/local/sbin`,
+connect an NC switch (i.e. one that connects when pressed) between pin 39 (GND)
+and pin 40 of the Raspberry Pi and add:
+
+~~~
+if [ -x /usr/local/sbin/gpio_trigger.py ]; then
+  /usr/local/sbin/gpio_trigger.py -D -H 5000 poweroff
+fi
+~~~
+
+to the file `/etc/rc.local`. This will start the script in the background (`-D`)
+to wait for pin 40 (default pin) to be connected to ground for 5000ms (`-H`) and
+then run the command `poweroff` to shutdown the Raspberry Pi.
+
+Please refer to the output of `gpio_trigger.py -h` for the options supported and
+defaults used when no option is specified.
+
+
+<a name=services>Systemd services</a>
+-------------------------------------
+The repository contains a number of `.service` files, which are systemd service
+descriptions to control specific on-board features of the Raspberry Pi (e.g. to
+disable unused ports). Their purpose should be pretty clear from their name (and
+comments they contain). The rationale of the initial scripts is covered in this
+[blog post](https://frederik.lindenaar.nl/2018/05/11/raspberry-pi-power-saving-disable-hdmi-port-and-others-the-systemd-way.html).
+
+In general, to install these copy them to the directory `/etc/systemd/system/`
+
+To manually disable the port, 'start' the 'service' with:
+
+~~~
+service <<filename without .service>> start
+~~~
+
+To manually enable the port again, 'stop' the 'service' with:
+
+~~~
+service <<filename without .service>> stop
+~~~
+
+To enable starting during system boot (to disable the port) run:
+
+~~~
+systemctl enable service <<filename without .service>>
+~~~
+
+To disable starting during system boot (to no longer disable the port) run:
+
+~~~
+systemctl disable service <<filename without .service>>
+~~~
+
+
+<a name="license">License</a>
+-----------------------------
+These scripts, documentation & configration examples are free software: you can
+redistribute and/or modify it under the terms of the GNU General Public License
+as published by the Free Software Foundation, either version 3 of the License,
+or (at your option) any later version.
+
+This script, documenatation and configuration examples are distributed in the
+hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
+warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+this program.  If not, download it from <http://www.gnu.org/licenses/>.

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'
+parser = ArgumentParser(
-                                    ' high or low (e.g. a button is pressed)')
+    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 --'
+parser.add_argument('arg', nargs='*', help='argument(s) for the command (*)')
-                        ' before first argument to stop parsing parameters')
 
 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
+        state = GPIO.input(args.pin)
-        if not args.continuous:                         # exit if running once
+        # pin changed, if required check if it is stays the same long enough
-            break
+        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

rpi_no_hdmi.service

@@ -0,0 +1,37 @@
+#
+# rpi_no_hdmi.service – Systemd service to disable the Raspberry Pi's HDMI port
+#
+# Version 1.0, latest version, documentation and bugtracker available at:
+#		https://gitlab.lindenaar.net/scripts/raspberrypi
+#
+# Copyright (c) 2019 Frederik Lindenaar
+#
+# This script is free software: you can redistribute and/or modify it under the
+# terms of version 3 of the GNU General Public License as published by the Free
+# Software Foundation, or (at your option) any later version of the license.
+#
+# This script is distributed in the hope that it will be useful but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+# A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, visit <http://www.gnu.org/licenses/> to download it.
+#
+
+# To install copy to /etc/systemd/system/rpi_no_hdmi.service
+# enable it to start during boot with:          systemctl enable rpi_no_hdmi
+# temporarily enable with:                      service rpi_no_hdmi start
+# temporarily disable with:                     service rpi_no_hdmi stop
+# disable starting during boot with:            systemctl disable rpi_no_hdmi
+
+[Unit]
+Description=Disable Raspberry Pi HDMI port
+
+[Service]
+Type=oneshot
+ExecStart=/opt/vc/bin/tvservice -o
+ExecStop=/opt/vc/bin/tvservice -p
+RemainAfterExit=yes
+
+[Install]
+WantedBy=default.target

rpi_no_usb.service

@@ -0,0 +1,37 @@
+#
+# rpi_no_usb.service – Systemd service to disable the Raspberry Pi's USB bus
+#
+# Version 1.0, latest version, documentation and bugtracker available at:
+#		https://gitlab.lindenaar.net/scripts/raspberrypi
+#
+# Copyright (c) 2019 Frederik Lindenaar
+#
+# This script is free software: you can redistribute and/or modify it under the
+# terms of version 3 of the GNU General Public License as published by the Free
+# Software Foundation, or (at your option) any later version of the license.
+#
+# This script is distributed in the hope that it will be useful but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+# A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, visit <http://www.gnu.org/licenses/> to download it.
+#
+
+# To install copy to /etc/systemd/system/rpi_no_usb.service
+# enable it to start during boot with:          systemctl enable rpi_no_usb
+# temporarily enable with:                      service rpi_no_usb start
+# temporarily disable with:                     service rpi_no_usb stop
+# disable starting during boot with:            systemctl disable rpi_no_usb
+
+[Unit]
+Description=Disable Raspberry Pi USB bus
+
+[Service]
+Type=oneshot
+ExecStart=/bin/sh -c "echo 0x0 > /sys/devices/platform/soc/3f980000.usb/buspower"
+ExecStop=/bin/sh -c "echo 0x1 > /sys/devices/platform/soc/3f980000.usb/buspower"
+RemainAfterExit=yes
+
+[Install]
+WantedBy=default.target

rpi_no_wifi.service

@@ -0,0 +1,37 @@
+#
+# rpi_no_wifi.service – Systemd service to disable WiFi on Raspberry Pi 3B/ZeroW
+#
+# Version 1.0, latest version, documentation and bugtracker available at:
+#		https://gitlab.lindenaar.net/scripts/raspberrypi
+#
+# Copyright (c) 2019 Frederik Lindenaar
+#
+# This script is free software: you can redistribute and/or modify it under the
+# terms of version 3 of the GNU General Public License as published by the Free
+# Software Foundation, or (at your option) any later version of the license.
+#
+# This script is distributed in the hope that it will be useful but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+# A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, visit <http://www.gnu.org/licenses/> to download it.
+#
+
+# To install copy to /etc/systemd/system/rpi_no_wifi.service
+# enable it to start during boot with:          systemctl enable rpi_no_wifi
+# temporarily enable with:                      service rpi_no_wifi start
+# temporarily disable with:                     service rpi_no_wifi stop
+# disable starting during boot with:            systemctl disable rpi_no_wifi
+
+[Unit]
+Description=Disable Raspberry Pi 3B/ZeroW WiFi interface
+
+[Service]
+Type=oneshot
+ExecStart=/sbin/ifdown wlan0
+ExecStop=/sbin/ifup wlan0
+RemainAfterExit=yes
+
+[Install]
+WantedBy=default.target

rpi_poweroff_button.service

@@ -0,0 +1,40 @@
+#
+# rpi_poweroff_button.service – Systemd service to implement a poweroff button
+#
+# Version 1.0, latest version, documentation and bugtracker available at:
+#		https://gitlab.lindenaar.net/scripts/raspberrypi
+#
+# Copyright (c) 2019 Frederik Lindenaar
+#
+# This script is free software: you can redistribute and/or modify it under the
+# terms of version 3 of the GNU General Public License as published by the Free
+# Software Foundation, or (at your option) any later version of the license.
+#
+# This script is distributed in the hope that it will be useful but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+# A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, visit <http://www.gnu.org/licenses/> to download it.
+#
+
+# Please note this requires gpio_trigger.py installed in /usr/local/sbin, see:
+# https://frederik.lindenaar.nl/2019/10/23/raspberry-pi-power-off-button.html
+
+# To install copy to /etc/systemd/system/rpi_poweroff_button.service
+# enable it to start during boot with:  systemctl enable rpi_poweroff_button
+# temporarily enable with:              service rpi_poweroff_button start
+# temporarily disable with:             service rpi_poweroff_button stop
+# disable starting during boot with:    systemctl disable rpi_poweroff_button
+
+[Unit]
+Description=Power-off button on GPIO
+
+[Service]
+Type=idle
+ExecStart=/usr/local/sbin/gpio_trigger.py --hold 5000 poweroff
+Restart=always
+RestartSec=30
+
+[Install]
+WantedBy=default.target