OpenSprinkler › Forums › OpenSprinkler Unified Firmware › Announcing OpenSprinkler Unified Firmware 2.1.3 (for AVR/RPI/BBB/LINUX) › Reply To: Announcing OpenSprinkler Unified Firmware 2.1.3 (for AVR/RPI/BBB/LINUX)
Yes, you can connect a rain sensor to your 1.1. Please check the OSPi user manual:
page 10, RPi pin uses. According to the diagram, the firmware uses GPIO 14 as rain sensor. What you need to do in terms of connection is: VCC (3.3V) -> 30K (or 27K) resistor -> one wire of rain sensor, and the other wire of the rain sensor -> GND. This way, the pin is pulled high by default, and when rain sensor clicks it’s pulled to ground.
The current version of OSPi also has a 4.7K resistor in series and a TVS in parallel to the rain sensor port, to protect it from transient voltages. These are optional, but can improve the reliability. For details, you can check the schematic: