A method, system, and apparatus for fault detection in a microprocessor-based system uses a serial data communication protocol for communications between a peripheral device and a controller. Peripheral device interface circuitry is adapted to intermittently receive input serial data frames from the controller using the serial communication protocol and to intermittently send output serial data frames to the controller using the serial communication protocol. Each output serial data frame includes one or more status bits representing communication status data and one or more data bits representing peripheral device data. The status bits and the data bits are serially followed by at least one fault bit that indicates whether a fault is detected during sending of the output serial data frame.