Using digital inputs on UniPi 1
Digital input serves for reading of/off state of connected devices like buttons, contacts etc. The following picture describes connection of external device to UniPi 1 while using the integrated 12V power supply, that is designed for such purpose.
So if you activate the connected device, the voltage turns on the input and the signal is evaluated as logic HIGH(1). If the device is deactivated (turned off), the state is evaulated as a logic LOW(0). Using this, you can read for example S0 impulses from energy meters (water meter, electricity meter, ...) or buttons, movement (PIR) sensors or magnetic contacts and many others.
To preserve galvanic isolation of the connected device and internal parts of UniPi, we recommend using external 5 - 24V DC power supply and follow the schematics shown below. Before connecting the device, make sure that jumpers JP2 - JP5 are configured acconrding to the documentation of UniPi 1. Please note that the negative pole of the power supply is be connected to the POx connector.