This is a simple daemon that facilitates access to the Raspberry Pi (RPi) GPIO ports from processes that are not running as root. This daemon, running as root, waits for connections on a Unix domain socket and implements a very simple command/response protocol to permit input and output from the GPIO ports. A typical application would be for a Web CGI script that needs access to the GPIO interface, since it's strongly advised not to run a web server as root.
- python-daemon 1.5.5
- raspberry-gpio-python 0.5.0
- All commands are initiated by the client program and are terminated by a newline character.
- port is the pin number on the RPi connector, not the Broadcom channel number.
- One response is generated per command, also terminated by a newline character.
- Commands are case-independent.
- Lines beginning with # are treated as comments
SETUP port OUT [LOW|HIGH]
Sets port as output. Optional parameter LOW or HIGH specifies the initial state of the port. Responds with 'ok' or an error message.
SETUP port IN [PULLUP|PULLDOWN]
Sets port as input. Optional parameter PULLUP or PULLDOWN specifies whether a pull up or pull down resistor is configured on the port; the default is no pull up or pull down. Responds with 'ok' or an error message.
OUTPUT port LOW|HIGH
Sets the state of the specified output port, and responds with 'ok' or an error message.
INPUT port
Reads the specified input port, and responds with its state: 'true' or 'false' or an error message.
SETUP 16 IN PULLUP
OUTPUT 11 HIGH
INPUT 16
- Copy
gpiod.pyto a suitable location, such as /usr/local/sbin - copy
gpiod(the init script) to /etc/init.d - Ensure that the modules listed above under Python Requirements have been installed
- Start the daemon and test with gpiotest.py
- If you want to initialize the interface when the daemon starts, create a script with gpiod commands at /etc/gpiod.cfg
Some ideas for enhancements include:
- More comprehensive support of the GPIO port capabilities, such as event detection (although this may also imply changes to the socket protocol).
- Better initialization using a pidfile
- Ability to specify a duration for timed output pulses
- Initial version