A disk drive is disclosed comprising a microprocessor and a power driver
for generating at least one actuator signal applied to the VCM actuator,
wherein a serial communication circuit is used to communicate with the
power driver. At least one control component periodically generates a
control signal, wherein the control signal is transmitted at a
substantially constant periodic interval using the serial communication
circuit, and a timer times the periodic interval. A job queue controller
queues and arbitrates serial communication requests to access the power
driver using the serial communication circuit. The serial communication
requests include a request to transmit the control signal and requests
generated by the microprocessor. The job queue controller services a
communication request generated by the microprocessor if the
communication request can be serviced before the timer expires.