Method and apparatus for compensating for mismatched delays in signals of a mobile display interface (MDDI) system

• US 8,812,706 B1
• Filed: 09/06/2002
• Issued: 08/19/2014
• Est. Priority Date: 09/06/2001
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Zou, Qiuzhen, Wiley, George A., Steele, Brian
• Primary Examiner(s): Harrell, Robert B
• Application Number:
  US10/236,657
• Time in Patent Office: 4,365 Days
• Field of Search: 709/203, 709/572, 709/230
• US Class Current: 709/230
• CPC Class Codes: G06F 3/14 Digital output to display device ; Cooperation and interconnection of the display device with other functional units
• CPC Class Codes: G09G 2370/10 Use of a protocol of communication by packets in interfaces along the display data pipeline
• CPC Class Codes: G09G 2370/16 Use of wireless transmission of display information
• CPC Class Codes: G09G 5/006 Details of the interface to the display terminal specific for a display terminal using a CRT G09G1/167; using a flat panel G09G3/2096; circuits for interfacing with colour displays G09G5/04
• CPC Class Codes: G09G 5/008 Clock recovery
• CPC Class Codes: G09G 5/12 Synchronisation between the display unit and other units, e.g. other display units, video-disc players
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/283 in response to processing delays, e.g. caused by jitter or round trip time [RTT]
• CPC Class Codes: H04L 47/41 by acting on aggregated flows or links
• CPC Class Codes: H04L 69/324 in the data link layer [OSI layer 2], e.g. HDLC
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

A method, apparatus, and computer program product embodied on a hardware computer readable storage medium for compensating mismatched delays in at least two signals of a mobile display digital interface (MDDI) system. The method, apparatus, and computer program product embodied on a hardware computer readable storage medium sends a skew calibration packet from a host to a client. The host begins a calibration pattern; then toggling a data signal and a strobe signal at a substantially similar time which strobe signal is used by the client as a clock source. The method, apparatus, and computer program product embodied on a hardware computer readable storage medium also aligns a timing of the strobe signal and the data signal by providing varying delays and resetting the client to an original clock source before a next packet reception.

Claims

1. A hardware apparatus for compensating mismatched delays in at least two signals of a mobile display digital interface (MDDI) system, the apparatus comprising:

means for sending a skew calibration packet from a host to a client;

means for beginning a calibration pattern by the host;

means for toggling a data signal and a strobe signal at a substantially similar time;

means for using the strobe signal as a clock source by the client;

means for aligning a timing of the strobe signal and the data signal by providing varying delays; and

means for resetting the client to an original clock source before a next packet reception.

2. The hardware apparatus of claim 1 further comprising a means for examining simultaneous transitions of the at least two signals to determine an optimal delay setting.

3. The hardware apparatus of claim 2 further comprising a means for repeating the examining step until the optimal delay setting is determined.

4. The hardware apparatus of claim 3 wherein the means for aligning comprises adjustable taps on a data signal path.

5. The hardware apparatus of claim 1 wherein the means for aligning comprises adjustable taps on a data signal path and a strobe signal path.

6. The hardware apparatus of claim 5 wherein the adjustable taps comprise a programmable delay circuit.

7. The hardware apparatus of claim 6 wherein the programmable delay circuit comprises a plurality of delay taps of different lengths.

8. The hardware apparatus of claim 1 wherein the means for using the strobe signal as a clock source also comprises a means for using the data signal as the clock source.

9. The hardware apparatus of claim 1 wherein the means for toggling further comprises a means for toggling the data signal and strobe signal at a substantially similar level.

10. The hardware apparatus of claim 1 wherein the varying delays comprise a safety margin.

11. The hardware apparatus of claim 1 wherein the means for aligning comprises a means for aligning an arrival time of the data signal and the strobe signal.

12. The hardware apparatus of claim 1 further comprising a means for using a successive approximation algorithm to adjust the varying delays to an optimal operation.

13. The hardware apparatus of claim 1 wherein the means for aligning comprises adjustable taps on a strobe signal path.

14. The hardware apparatus of claim 1 wherein the at least two signals comprise a plurality of signals.

15. A method executed on hardware for compensating mismatched delays in at least two signals of a mobile display digital interface (MDDI) system, the method comprising the steps of:

sending a skew calibration packet from a host to a client;

beginning a calibration pattern by the host;

toggling a data signal and a strobe signal at a substantially similar time;

using the strobe signal as a clock source by the client;

aligning a timing of the strobe signal and the data signal by providing varying delays; and

resetting the client to an original clock source before a next packet reception.

16. The method of claim 15 wherein the step of aligning comprises adjusting taps on a data signal path and a strobe signal path.

17. The method of claim 16 wherein the step of adjusting taps comprises adjusting the data signal path with a programmable delay circuit.

18. The method of claim 17 wherein the programmable delay circuit comprises a plurality of delay taps of different lengths.

19. The method of claim 15 further comprising the step of examining simultaneous transitions of the at least two signals during the aligning step to determine an optimal delay setting.

20. The method of claim 19 further comprising repeating the examining step until the optimal delay setting is determined.

21. The method of claim 15 wherein the step of using the strobe signal as a clock source comprises also using the data signal as the clock source.

22. The method of claim 15 wherein the step of toggling further comprises toggling the data signal and strobe signal at a substantially similar level.

23. The method of claim 15 wherein the varying delays comprise a safety margin for a next data signal.

24. The method of claim 15 wherein the step of aligning comprises aligning an arrival time of the data signal and the strobe signal.

25. The method of claim 15 further comprising the step of using a successive approximation algorithm to adjust the varying delays to an optimal operation.

26. The method of claim 15 wherein the step of aligning comprises adjusting taps on a data signal path.

27. The method of claim 15 wherein the step of aligning comprises adjusting taps on a strobe signal path.

28. The method of claim 15 wherein the at least two signals comprise a plurality of signals.

29. A hardware apparatus for compensating mismatched delays in at least two signals of a mobile display digital interface (MDDI) system, the apparatus comprising:

a skew calibration packet for sending from a host to a client;

a calibration pattern provided by the host;

a toggle for toggling a data signal and a strobe signal to a substantially similar time;

a clock source for the client comprising the strobe signal;

varying delays for aligning a timing of the strobe signal and the data signal; and

a resetting structure for resetting the client to an original clock source before a next packet reception.

30. The hardware apparatus of claim 29 wherein the varying delays for aligning comprise adjustable taps on a data signal path and a strobe signal path.

31. The hardware apparatus of claim 30 wherein the adjustable taps comprise a programmable delay circuit.

32. The hardware apparatus of claim 31 wherein the programmable delay circuit comprises a plurality of delay taps of different lengths.

33. The hardware apparatus of claim 29 wherein clock source also comprises the data signal.

34. The hardware apparatus of claim 29 wherein the toggle is further adapted to toggle the data signal and strobe signal at a substantially similar level.

35. The hardware apparatus of claim 29 wherein the varying delays comprise a safety margin.

36. The hardware apparatus of claim 29 wherein the varying delays for aligning comprise a delay for aligning an arrival time of the data signal and the strobe signal.

37. The hardware apparatus of claim 29 wherein the varying delays for aligning comprise adjustable taps on a data signal path.

38. The hardware apparatus of claim 29 wherein the varying delays for aligning comprise adjustable taps on a strobe signal path.

39. The hardware apparatus of claim 29 wherein the at least two signals comprise a plurality of signals.

40. A computer program product embodied on a hardware computer readable storage medium comprising:

code for causing a compensation for mismatched delay in at least two signals of a mobile display digital interface (MDDI) system, the code comprising;

code for causing a skew calibration packet being sent from a host to a client;

code for causing a calibration pattern to be started by the host;

code for causing a data signal and a strobe signal to be toggled at a substantially similar time;

code for causing the strobe signal to be used as a clock source by the client;

code for causing a timing of the strobe signal and the data signal to be aligned by providing varying delays; and

code for causing the client to reset to an original clock source before a next packet reception.