gpio-watch

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

Synopsis

gpio-watch [-D 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 -D /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.

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.

License

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/.