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fartd

Implementation of the Fart Detector suggested by the Raspberry Pi Foundation here:

https://www.raspberrypi.org/learning/fart-detector/

This is an alternative software implementation for the given hardware setup:

  • It's written in C
  • It uses the gpio(3) library provided since FreeBSD 11
  • It is a daemon that logs air quality changes as they happen, using syslog(3)
  • It constantly shows status with three LEDs (intended as green/yellow/red)
  • 2c BSD License

Installation

Simply run make all install. It will compile and install the awesome fartd binary, along with an appropriate RCng script. All you need to do is to set fartd_enable=yes in your rc.conf.

Requirements

Be sure to double-check all the Pin numbers that are hardcoded in the .c file! You can change them as needed, of course.

The resistorpins[4] correspond to resistors R1, R2, R3, R4 and are configured to the same pins as they are in the reference implementation (GPIO 17, 18, 22, 23). In the same manner, the detection pin is expected at GPIO 4.

The LEDs are expected at:

  • Green: GPIO 16
  • Yellow: GPIO 20
  • RED: GPIO 21

Tuning

If necessary, you can adjust the LEVEL_* constants to have different thresholds.

If air quality is actually better than a certain level, no LED is active at all. The expected normal condition is something in between (only the green LED is active).

Debugging

If you run fartd -d, it won't fork(2) and will print to STDOUT instead of syslog.

Also you may want to increase sleep_calibrate (default disabled) to check the activation of the individual resistor ladder combinations.

Feedback

You're welcome to provide feedback to [email protected] (or via github). Especially if you happen to connect this to an SNMP daemon somehow, please let me know.