A controller for controlling the reverse-bias voltage of an avalanche photodiode in a transceiver or receiver. The controller includes memory for storing information related to the avalanche photodiode, and analog to digital conversion circuitry for receiving an analog signal corresponding to the temperature of the avalanche photodiode, converting the received analog signal into a digital value, and storing the digital value in a predefined location within the memory. Control circuitry in the controller controls the operation of the avalanche photodiode and a temperature lookup table store in the memory. A serial interface enables a host device to read from and write to locations within the memory. The invention also controls the reverse-bias voltage of an avalanche photodiode in a transceiver or receiver.