Frame detector for use in graphics systems
AssigneeSun Microsystems, Inc.
InventorsWilliam K. Chan, Nathaniel David Naegle
Life of this patent
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Abstract
One embodiment of a method of frame detection may involve storing data indicative of a pulse duration and a number of successive occurrences of pulses having that pulse duration for each of several different pulse durations detected within a first field of a composite synchronization signal. This process may be repeated for one or more other fields of the composite synchronization signal. The data stored for each of the fields may be compared, and a frame signal may be generated dependent on an outcome of said comparing.
Claims30
A frame detector configured to operate in a plurality of frame detection modes, the frame detector comprising:
- a measurement unit configured to generate data indicative of a duration of each of a plurality of pulses included in a composite synchronization signal;
- a counter configured to generate data indicative of a number of successive occurrences of pulses having a same duration;
- a memory coupled to the measurement unit and the counter and configured to store pattern data detected during each of a plurality of fields, wherein the pattern data for each field includes data indicative of two or more pulse durations generated by the measurement unit, wherein the pattern data for each field further includes data indicative of two or more counts generated by the counter, wherein each count is associated with a respective one of the two or more pulse durations;
- a control unit coupled to the memory and configured to perform a comparison of the pattern data stored during each of the plurality of fields and to identify which pattern data identifies a first field in a frame dependent on the comparison;
- and
- a mode register coupled to the control unit;
- wherein storing one value of a plurality of values in the mode register determines a corresponding mode of operation of the frame detector, and
- wherein one of the corresponding modes is a training mode in which the frame detector is supplied with the composite synchronization signal and a frame signal corresponding to the frame signal encoded in the composite synchronization signal.
A method for operating a multi-mode frame detector, the method comprising:
- storing data indicative of a pulse duration and data indicative of a number of successive occurrences of pulses having the pulse duration, for each of a plurality of different pulse durations detected in a field of a composite synchronization signal;
- repeating said storing for one or more other fields of the composite synchronization signal;
- receiving a frame signal if in a training mode and identifying which field's data corresponds to an occurrence in the frame signal of a first field in a frame in response to said receiving the frame signal, wherein the frame signal corresponds to a frame signal encoded in the composite synchronization signal;
- comparing data stored for each of the fields of the composite synchronization signal if not in a training mode;
- and
- generating and outputting a frame signal dependent on an outcome of said comparing if not in a training mode.
A method for operating a multi-mode frame detector, the method comprising:
- storing data indicative of a plurality of patterns, wherein each pattern is detected during one of a plurality of fields within a composite synchronization signal received by the frame detector, wherein each pattern includes at least two pulse measurements and at least two counts, wherein each count indicates a number of successive occurrences of pulses having a respective one of the at least two pulse measurements;
- during a training mode, detecting an edge in a frame signal received by the frame detector during one of the plurality of fields and responsively identifying one of the patterns as indicative of a first field in a frame, wherein the frame signal corresponds to a frame signal encoded in the composite synchronization signal;
- and
- during a non-training mode, toggling a frame signal output from the frame detector in response to detecting a pattern matching the one of the patterns identified as indicative of the first field in the frame.
Dependencies are inferred from the claim text.