Abstract: A direct memory access (DMA) controller transmits and receives formatted data frames having frame headers in a communications subsystem. The DMA controller includes a transmit input and output, a receive input and output, transmit circuitry, receive circuitry, a receive frame header capture circuit, a receive frame action table and a response message table. The transmit circuitry receives transmit data frames on the transmit input and applies the transmit data frames to the transmit output. The receive circuitry receives receive data frames on the receive input and applies the receive data frames to the receive output. The receive frame header capture circuit obtains a frame header from the received data frames and applies the frame header to the receive frame action table. The receive frame action table generates a frame action command based on the frame header field.

Abstract: An automatic baud rate detector circuit includes a serial input, a counter, a register, a comparator and a state machine circuit. The serial input receives a serial data stream having a bit defined by a first transition from a first logic state to a second logic state and next subsequent second transition from the second logic state to the first logic state. A counter increments a sample count in response to a clock signal when a count enable signal supplied to the counter is active. A register coupled to the counter stores the sample count as a minimum count when a load control signal supplied to the counter is active. The comparator is coupled to the counter and the register and generates a compare signal which indicates whether the sample count is less than the minimum count. The state machine circuit is coupled to the serial input for receiving the serial data stream and supplies the count enable signal to the counter and the load enable signal to the register.