My little Raspberry Pi seems to be growing arms and legs.

The other day I hooked up a simple PIR to it. I can’t remember where I got it, but it runs off 5v, consumes a low enough amount of milliAmps to be directly connected to the Raspberry Pi 5v supply, and outputs a TTL compatible 3.3v signal. Bonus!

I wanted to be able to signal to my MQTT broker when motion was detected, so it was time to start monitoring the GPIO pins. I wrote up this short app using the framework I’d made for MQTT-Republisher earlier. MQTT-GPIO-Trigger will accept a list of GPIO pins that you wish to watch, and will cycle through them all and fire off MQTT messages on any state change.

It uses the standard Linux sysfs interface to read the pin states, and if it detects the WiringPi library on the system it will use Gordons gpio command to export the pins to the system.