The UNI/O protocol was created by microchip and is a 1 wire bus.

Voltage Range

Not specified by the protocol so dependent on the devices being used.


A pull up resistor is not required but advisable so the bus is idle if the master is not driving it. The value is dependent on bus voltage and other factors – see here. Based on the calculation is this datasheet:

5V bus, Rpmin = 15K33, Rpmax = 150K

3V3 bus, Rpmin = 9K666Rpmax = 99K



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