Skew measurement for receiving frame-groups

Abstract

A system and method for asynchronously transmitting data blocks, in parallel, across multiple fibers in a serial manner. Frame groups are provided as a mechanism to transmit associated data serially on each fiber and tie the data being transmitted together. The frame groups do not have sequence numbers, therefore, the receiver determines which frames are part of a frame group by the arrival times of the individual frames. The transceivers for each member of the parallel bus asynchronously achieve synchronism from either end of the fiber. A receiver of a transceiver determines a relative skew on a conductor of a link by performing skew measurements on a series of calibration frames sent by a transmitter on another end of said link. A skew monitor performs skew measurements and includes a plurality of skew measurement registers for measuring the relative skew between frames of a frame group, each register having an input from a skew counter, and outputs coupled to a microprocessor controlling the monitor. Each register gates in the value in the skew counter at the time a link control word is received. The receiver can determine that one or more frames of the calibration frames have been lost and have not exceeded the maximum measureable skew limits.