METHOD AND APPARATUS FOR RECOVERY OF TIME SKEWED DATA ON A PARALLEL BUS

摘要

An apparatus and method for receiving time skewed data from a parallel data bus. A data transfer on the parallel data bus is preceded by a start-of-cell delimiter consisting of a predetermined sequence of pulses on each of the data signals. The data is received from the bus by receive logic employing a local clock. Sampling logic is used to sample each of the data signals received from the bus at a rate which is higher than the local clock rate. Sample registers store a plurality of samples of corresponding data signals, the number of samples stored being large enough to store at least some of the pulses constituting the start-of-cell delimiter. Start-of-cell detect and center select logic is used for determining that a start-of-cell delimiter is stored in each of the sample registers for determining which of the samples stored in each of the sample registers represents the approximate center sample of one of the pulses of the start-of-cell delimiter. These center samples correspond to the data signals on the bus, but are de-skewed and synchronous with the local clock.