An
integrated circuit with an interface circuit is described. During operation, the interface circuit may receive signals corresponding to a header of a frame that is compatible with a
serial communication protocol, where the received signals include a temporal pattern of binary bits with instances of a dominant
signal level and a recessive
signal level. Then, the interface circuit may compute a set of conditions based at least in part on the receive signals, where, when valid, the set of conditions identify a first dominant bit in the binary bits having the dominant
signal level. Moreover, when the set of conditions are valid, the interface circuit may: determine a location of synchronization field in the header relative to the identified first dominant bit; and calculate a
baud rate of the receive signals based at least in part on a subset of the binary bits in the synchronization field.