OpenSprinkler › Forums › Hardware Questions › OpenSprinkler Pi (OSPi) › Need to know what stable version of OSPi/UI to use! › Reply To: Need to know what stable version of OSPi/UI to use!
I apologize for the confusion however if you are using OSPi, you can use any version of the software as you can upgrade to the latest.
Just follow the instructions on the latest firmware using a clean Raspbian image and you should be up and running without issues: https://opensprinkler.com/forums/topic/announcing-opensprinkler-unified-firmware-2-1-4/
Please note, the mobile app is an application you download from the App Store (such as iOS, Android, Windows Phone, etc). It is no longer something you install on the device.