PREAMBLE DETECTION AND POSTAMBLE CLOSURE FOR A MEMORY INTERFACE CONTROLLER
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Abstract
A memory controller, such as a memory controller for reading data received from a DDR SDRAM memory, may detect the beginning and end of a read cycle. The memory controller may include a preamble detection circuit to receive a strobe signal and output a first control signal indicating detection of a preamble window in the strobe signal that indicates a beginning of the read cycle, where the first control signal is delayed based on a selectable delay period applied to the first control signal. The memory controller may further include a first gate to, based on the first control signal, either output the strobe signal for reading of the data lines or block the strobe signal, and the control logic to set an amount of the selectable delay period for the preamble detection circuit.
10 Citations
43 Claims
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1-23. -23. (canceled)
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24. A device comprising:
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a memory; and a memory controller comprising; a preamble detection circuit comprising; a first multiplexer, and a second multiplexer to provide a first signal indicating detection of a beginning of a read cycle from the memory; control logic to select outputs of the first multiplexer and the second multiplexer, where the control logic is to determine the outputs to select for the first multiplexer and the second multiplexer during a training cycle in which a strobe signal is sampled over a plurality of data read cycles, and in which, during different ones of the plurality of data read cycles, different combinations of the outputs of the first multiplexer and the second multiplexer are selected, and where the control logic is to perform the training cycle when the device is initially powered-up or reset; and a first gate connected to output the strobe signal or block the strobe signal based on the first signal. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31)
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32. A memory controller comprising:
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a preamble detection circuit comprising; a first multiplexer, and a second multiplexer to provide a first signal indicating detection of a beginning of a read cycle from a memory device; a postamble detection circuit to output a second signal indicating an end of the read cycle from the memory device; a first gate connected to output a strobe signal or block the strobe signal based on the first signal and the second signal; and control logic to output signals that control a selection of the first multiplexer and the second multiplexer, where the control logic is to determine the selection of the first multiplexer and the second multiplexer during a training cycle in which the strobe signal is sampled over a plurality of data read cycles, and in which, during different ones of the plurality of data read cycles, different combinations of outputs of the first multiplexer and the second multiplexers are selected. - View Dependent Claims (33, 34, 35, 36, 37)
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38. A method comprising:
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determining a delay during a training cycle in which a strobe signal is sampled over a plurality of data read cycles, and in which, during different ones of the plurality of data read cycles, different combinations of outputs of a first multiplexer and a second multiplexer are selected; selecting a first output corresponding to one of a plurality of flip-flops, to output from the first multiplexer, based on the delay; providing to the first output to a plurality of serially connected delay elements; selecting a second output corresponding to one of the plurality of serially connected delay elements, to output as a first signal from the second multiplexer, based on the delay; and controlling a gate to pass or block the strobe signal based on the first signal. - View Dependent Claims (39, 40, 41, 42, 43)
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Specification