Multimode system for calibrating a data strobe delay for a memory read operation

A method of operating a calibration subsystem of a memory controller of a processor-based system in multiple modes to coordinate a data strobe with a data valid window for a data read operation from a memory module, including the steps of:

• storing a first value in a configuration table coupled to the memory controller, the first value relating to a first mode of operation and configured to initiate a calibration operation in response to a nonperiodic trigger;
• storing a second value in a configuration table coupled to the memory controller, the second value relating to a second mode of operation and configured to initiate a calibration operation at predetermined intervals.

A multimode circuit for coordinating arrival of a first signal and a second signal at a receiving device, where the second signal is coupled to a signal path, including:

• a calibration subsystem configured to generate a calibration delay time for a calibration signal to pass through a calibration path, the calibration path being configured to have an effective path length substantially matching an effective path length for at least a portion of the signal path;
• and
• selection logic configured to select one of the calibration delay time and an actual delay time as a delay value to apply to the first signal.