I built Opensprinkler Pi based on v1.4+ PCB. I chose this PCB version because it has a built in relay. I considered this as the most useful extra output, e.g. for an additional station control.
Unfortunately neither the current firmware nor the app supports the relay control. Is there any chance to include this kind of control?
The relay feature has been retired since early this year. It’s partly because very few users are actually using this feature, and those who do can use an external 24VAC relay instead. A while back I wrote a blog post about using 24VAC relay with OpenSprinkler: https://opensprinkler.com/using-24v-ac-relays-with-opensprinkler/