A controller for compensating a voltage drop on a cable includes an output stage coupled to a channel configuration pin of the source device, a processor coupled to a power supply pin of a source device, and an error amplifier that includes a positive input coupled to a reference voltage, a negative input coupled to the channel configuration pin, a first output coupled to the output stage, and a second output coupled to the processor. The error amplifier is configured to supply a first signal to the output stage indicating a voltage difference between the reference voltage and a voltage at the channel configuration pin. The output stage is configured to supply an output current to the processor using the voltage drop and a stored current determined using the first signal. The processor is configured to generate a compensated supply voltage on the power supply pin using the output current.