Data capture window synchronizing method for generating data bit sequences and adjusting capture window on parallel data paths

Abstract

A self test function in the Memory Controller is utilized to generate unique and continuous data patterns for each of the words which are stored into two consecutive DRAM addresses in two spaced store operations. The self test function then generates fetch commands to read back the unique data patterns from the two DRAM addresses. In the fetch operations, the data transmission for each operation and between both operations is contiguous (no gaps). A self test data comparison function is then used to compare these fetched data words to data patterns which are generated from the self test data generator. Bit error counters from the memory controller keeps track of any miscompares. By reading out a unique signature from these bit counters, it can be determined whether the store path data are misaligned early or late or correct and/or the fetch path data are misaligned early or late or correct. In addition, the exact number of cycles the data are early or late is known. Based on the last results, either or both the store and/or fetch data path capture window parameters are adjusted to correct or early or late bit position.