UPDATE: Information outdated, OSPi now uses a different interface. Please update OSPi software if the problem persists.
Currently the firmware for OSPi does NOT work with Raspberry Pi Bullseye. The problem is, the required library “WiringPi” is no longer included.
Use the legacy version “Buster”: https://www.raspberrypi.com/software/operating-systems/
Details here:
https://github.com/OpenSprinkler/OpenSprinkler-Firmware/issues/196
However, you can reinstall these using these commands:
wget https://github.com/WiringPi/ WiringPi/releases/download/2. 61-1/wiringpi-2.61-1-armhf.deb
sudo dpkg -i wiringpi-2.61-1-armhf.deb

I'm using OpenSprinkler on Bullseye and it works fine for me. This was after installing OpenSprinkler on a clean install of buster. Maybe there is a certain function that is not working? What is the problem?
Hi, when installing directly with Bullseye, the WiringPi library is missing.
Installation from buster and upgrade to Bullseye will keep the WiringPi library, so everything is ok.