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gpio-watch

gpio-watch is a tool for running scripts in response to GPIO events.

Synopsis

gpio-watch [-s script_directory] [-e default_edge] [pin[:edge]] ...

Description

gpio-watch was written to make it easy to connect external edge-triggered sensors -- like pushbuttons -- to a Raspberry Pi (or other computer with available GPIO lines). It will watch a set of pins for events, and will trigger shell scripts in response to those events.

gpio-watch accepts a list of pins to watch for events. By default it will trigger on both rising and falling events, but you can change the default behavior with the -e default_edge command line option.

You may also modify the behavior per-pin by appending an edge mode after the pin number, such as 4:rising to monitor the rising edge on pin 4.

Options

  • -s script_directory -- location in which gpio-watch will look for event handling scripts. Scripts must be named after the pin number triggering the event. For example, if you specify -s /etc/gpio-scripts, and gpio-watch processes an event on pin 4, it will attempt to run /etc/gpio-scripts/4.

    Defaults to /etc/gpio-scripts.

  • -e default_edge -- specifies whether gpio-watch should monitor rising, falling, or both edges by default. You can also specify edge detection per-pin.

    The special keyword switch activates switch debouncing logic. In this mode, gpio-watch sets the edge mode to both but only activates the event script when the button has been released. The release (falling) event must happen more than DEBOUNCE_INTERVAL (current hardcoded as 100000 nanoseconds) after the press (rising) event to activate the script.

    For pins with a pull-up resistor switchup will work the same as switch but treats the falling edge as the press and the rising edge as the release.

Example

Watch switches connected to pins 21, 22, and 23:

gpio-watch -e switch 21 22 23

If you were to press a button connected to pin 23, gpio-watch would attempt to run:

/etc/gpio-scripts/23 23 0

That is, the event script is called with both the pin number and the current pin value to permit a single script to handle multiple events.

Build & install

make
sudo make install

License

gpio-watch, a tool for running scripts in response to gpio events Copyright (C) 2014 Lars Kellogg-Stedman [email protected]

This program is free software: you can redistribute it 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 program 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, see http://www.gnu.org/licenses/.