Continuous adaptive data capture optimization for interface circuits

A method for operating a data interface circuit whereby calibration adjustments are frequently made during normal system operation and without disturbing normal system operation, comprising;

• initially establishing, using a first calibration method, an optimal sampling point for sampling data bits received by an input of the data interface circuit;
• from time to time during system operation, and without disturbing normal system operation, performing a second calibration method that is different from the first, the second calibration method comprising:
• sampling transition edges of data bits received by the input, wherein values of the received data bits represent a random pattern from perspective of the data interface circuit;
• wherein for the second calibration method sampling the fringe timing points associated with the transition edge of a data bit comprises sampling:
• a) a plurality of interfringe timing points;
• and b) an intrafringe timing point;
• determining that the transition edges have drifted relative to the optimal sampling point by a drift delay amount, the drift having occurred since a previous creation or adjustment of the optimal sampling point;
• adjusting the optimal sampling point by adding or subtracting the drift delay amount from, or adding the drift delay amount to, the optimal sampling point to create a revised optimal sampling point;
• and
• wherein the first calibration method requires a specific data pattern to be provided to the input of the data interface circuit, and the second calibration method operates successfully on any random pattern of data bit values provided to the input of the data interface circuit.

A method for operating a data interface circuit whereby calibration adjustments for data bit capture are made without disturbing normal system operation, comprising;

• initially establishing, using a first calibration method where a data bit pattern received by the data interface circuit is known and predictable, an optimal sampling point for sampling data bits received by the data interface circuit;
• during normal system operation and without disturbing normal system operation, performing a second calibration method where the data bit pattern received by the data interface circuit is unknown and unpredictable, and wherein the second calibration method determines an amount of timing drift for received data bit edge transitions and adjusts the optimal timing point determined by the first calibration method to create a revised optimal timing point;
• wherein from time to time during system operation, and without disturbing normal system operation, performing the second calibration method where the data bit pattern received by the data interface circuit is unknown and unpredictable, and wherein the second calibration method determines an amount of timing drift for received data bit edge transitions and adjusts the revised optimal timing point to create a new revised optimal timing point;
• wherein for the second calibration method sampling the fringe timing points associated with the transition edge of a data bit comprises sampling:
• a) a plurality of interfringe timing points;
• and b) an intrafringe timing point.