Periodic Calibration For Communication Channels By Drift Tracking
A method and system that provides for execution of a first calibration sequence, such as upon initialization of a system, to establish an operation value, which utilizes an algorithm intended to be exhaustive, and executing a second calibration sequence from time to time, to measure drift in the parameter, and to update the operation value in response to the measured drift. The second calibration sequence utilizes less resources of the communication channel than does the first calibration sequence. In one embodiment, the first calibration sequence for measurement and convergence on the operation value utilizes long calibration patterns, such as codes that are greater than 30 bytes, or pseudorandom bit sequences having lengths of 2 N −1 bits, where N is equal to or greater than 7, while the second calibration sequence utilizes short calibration patterns, such as fixed codes less than 16 bytes, and for example as short as 2 bytes long.
1 . An integrated circuit device adapted for use in a mesochronous memory system in which two components communicate data and in which channel timing is periodically calibrated, the integrated circuit device comprising:
means for performing a first calibration operation associated with communication across the channel to identify a data eye timing point;
means for periodically performing drift tracking using a second calibration operation in which drift tracking uses an expected timing point location and identifies drift associated expected timing point location; and
means for, in response to drift tracking, updating the data eye timing point.
2 . An integrated circuit device, comprising:
transmitter circuitry adapted to perform
a first calibration operation associated with communication across a channel to identify a data eye timing point, and
a second calibration operation to perform drift tracking using an expected timing point location, the second calibration operation identifying drift associated expected timing point location; and
adjustment circuitry to update, in response to drift tracking, the data eye timing point.