Method and apparatus for multi-channel data delay equalization

• US 6,647,027 B1
• Filed: 11/10/1999
• Issued: 11/11/2003
• Est. Priority Date: 11/10/1999
• Status: Expired due to Term

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: LSI Logic Corporation (Broadcom, Inc.)
• Inventors: Smith, Paul J., Gasparik, Frank
• Primary Examiner(s): Nguyen, Chau
• Assistant Examiner(s): HYUN, SOON D
• Application Number:
  US09/437,454
• Time in Patent Office: 1,462 Days
• Field of Search: 370/516, 370/517, 370/518, 370/519, 370/503, 370/507, 375/354, 375/356, 375/371-373, 713/500, 713/501, 713/502, 713/503, 713/600, 713/601, 327/141, 327/151, 327/156, 327/160
• US Class Current: 370/519
• CPC Class Codes: G06F 13/423 with synchronous protocol
• CPC Class Codes: G06F 2213/0036 Small computer system interface [SCSI]
• CPC Class Codes: H04L 25/14 Channel dividing arrangements , i.e. in which a single bit stream is divided between several baseband channels and reassembled at the receiver
• CPC Class Codes: H04L 7/0338 the correction of the phase error being performed by a feed forward loop
• CPC Class Codes: H04L 7/10 Arrangements for initial synchronisation

Abstract

A method and apparatus for managing transmission of data signals in a plurality of data lines. Data signals are received on the data lines and a reference signal. On each of the data lines, a delay between the data signal and the reference signal is measured to form a plurality of delay measurements. A set of delay values from the delay measurements is generated. In a preferred embodiment of the present invention, the delay values are selected to equalize the delay in each of the data lines to have the same delay as the data line having the longest delay. The delay values are used to adjust delay in a transmission in each of the plurality of data signals in the data lines. In the preferred embodiment of the present invention, the reference signal is set such that transitions for the data signals are centered to the middle of a pulse for the reference signal.

Claims

1. A method for managing, reception of data signals on a plurality of data lines, the method conspiring:

receiving data signals on the plurality of daunt lines and a reference signal;

measuring a delay between the data signal a and the reference signal on each of the plurality of data lines, based on a periodic timing reference to form a plurality of delay measurements;

generating a set of delay values from the plurality of delay measurements; and

using the set of delay values to adjust delay in a reception in each of the plurality or data signals in the plurality of data lines.

2. The method of claim 1, wherein a delay value is selected for a data line in the plurality of data lines to adjust a delay for the data line to a slowest data line within the plurality of data lines.

3. The method of claim 7, wherein the plurality of data lines arc in a small computer system interface bus.

4. The method of claim 1, wherein the plurality of data lines is sixteen.

5. The method of claim 1, wherein the delay in a data line within the plurality of data lines is implemented using a delay chain.

6. The method of claim 1, wherein the receiving, measuring, and generating steps arc performed in response to a command from a host device.

7. The method of claim 1, wherein the receiving, measuring, and generating stops are performed periodically and changes in delay caused by temperature changes are minimized.

8. The method of claim 1, wherein the reference signal is an acknowledgement signal.

9. The method of claim 1, wherein the measuring step is accomplished using a delay counter.

10. The method of claim 1, wherein the data signal is a test signal.

11. The method of claim 1, wherein the plurality of data lines required a different delay value.

12. The method of claim 1, wherein the step of generating a set of delay value comprises:

identifying a data line within the plurality of data lines having a longest delay within the plurality of delay measurements; and

selecting delay values for other data lines within the plurality of delay lines, wherein the delay values set the delay for the other data lines equal to the data line.

13. The method of claim 12, further comprising:

selecting a delay value for the reference signal, wherein the delay value causes transitions in the data signals received from the plurality of lines to occur during a middle of a pulse for the reference signal.

14. The method of claim 1, wherein the step of generating a set or delay value comprises:

identifying a largest delay within the set or delay values;

selecting delay value for each of the plurality of data lines equal to the largest delay minus the delay for each of the data line plurality of data lines.

15. The method of claim 1, wherein the receiving, measuring, and generating steps are performed in a target device.

16. The method of claim 1, wherein the receiving, measuring, and generating steps are performed in a host device.

17. A method for equalizing a reception of data signals in a plurality of input channels in a device, the method comprising:

receiving a data signal from each of the plurality of input channels in the device and a reference signal;

identifying a delay between a transition in the data signal and a transition in the reference signal on each channel of the plurality of input channels, based on a periodic timing reference, to form a plurality of delays; and

using the plurality of delays to adjust a delay in a reception of a data signal on each channel within the set of input channels to increase a setup and a hold time for the plurality of data signals.

18. The method of claim 17, wherein the reference signal is an acknowledgment signal.

19. The method of claim 17, wherein the plurality of input channels lines are in a small computer system interface device.

20. The method of claim 17, wherein the plurality of input channels is sixteen.

21. The method of claim 17, wherein the receiving and identifying steps are performed in response to a signal from a lost device.

22. The method of claim 17, wherein the receiving and identifying steps are performed periodically.

23. The method of claim 17, wherein the delay in an imput channel with the plurality of input channels is implemented using a plurality of delay chains.

24. A data processing system comprising:

a plurality of data lines;

a host device connected to the plurality of data lines, wherein the host device transmits a data signal on each of the plurality or data lines to form a set or transmitted data signals and transmits another signal; and

a target device connected to the plurality of data lines, wherein the target device receives the set of transmitted data signals, nicasures a delay between a transmitted data signal in the set of transmitted data signals and the another signal for each of the plurality of transmitted data signals, based on a periodic timing reference, to generate a sot of delay values, adjusts a delay at the target device for each of the plurality of data lines based on the set of delay values.

25. The data processing system of claim 24, wherein the target device includes a set of delay counters, wherein each delay counter is associated with a data line in the plurality of data lines and each delay center in the set of delay counters is used to measure a period of time between a transition data signal and the another signal.

26. The data processing system of claim 25, wherein the target device includes a delay adjustment calculator, wherein the delay adjustment calculator generates the set of delay values using delays measured by the set of delay counters.

27. The data processing system of claim 26, wherein the target device includes a set of input delay adjust units, wherein each input delay adjust unit is connected to a data line within the plurality of data lines and delays transmission of a signal using a delay value for the data line from the set of delay values.

28. The data processing system of claim 24, wherein the plurality of data lines form a small computer system interface bus.

29. The data processing system of claim 24, wherein the data processing system is a personal computer.

30. The data processing system of claim 24, wherein the data processing system is a workstation.

31. A channel delay apparatus comprising.

a delay adjustment unit, a first set of inputs for receiving data from a plurality of data channels, a second set of inputs for receiving, a set of delay values, and set of outputs at which the data received at the first set of inputs is transmitted, and a delay mechanism, wherein the delay mechanism delays travelling from the first set of inputs to the set of outputs based on the set of delay values, wherein data for a data channel in the set of data channels is delayed relative to data for another data channel in the set of data channels using a delay value from the set of delay values;

a delay counter unit having a first set of inputs for receiving data from the plurality of data channels and a reference signal from a signal line and a set of outputs, wherein the delay counter unit is based on a periodic timing reference and measures a delay between data in each of the plurality of data channels and the reference signal on the signal line and generates a set of measured delay values at the set of outputs; and

a delay adjustment calculation unit having a plurality of inputs corrected to the set of outputs in the delay counter and a set of outputs connected to the second set of inputs in the delay adjustment unit, wherein the delay calculation unit generates the set of delay values using the set of measured delay values.

32. The channel delay apparatus of claim 31, wherein the apparatus is located in a host bus adapter.

33. The channel delay apparats of claim 31, wherein the apparatus is located in disk drive.

34. The channel delay apparatus of claim 31, wherein the input adjust delay unit includes a plurality of delays.

35. The channel delay apparatus of claim 32, wherein each of the plurality of delays includes a set of delay elements connected in series.

36. The channel delay apparatus of claim 35, wherein data is transmitted through the set of delay elements, wherein each of the set of delay elements includes an output, and wherein the channel delay apparatus delays a signal traveling from an input in the first set of output in the set of outputs by selecting an output from the set of delay elements.

37. The delay channel apparatus of claim 31, wherein the reference signal is an acknowledgement signal.

38. The delay channel apparatus of claim 31, wherein the delay counter unit includes a plurality of delay counter circuits, wherein each of the plurality of delay courtier circuits is associated with a data channel within the plurality of data channels and comprises:

a first transition detector having an input configured to receive data and an output;

a second transition detector having an input configured to receive the reference signal ailed an output;

a first latch having a first input, a second input, and an output, wherein the first input is connected to the output of the first transition detector and the second input is connected to the output of the first transition detector;

a counter having a first input, a reset input, a clock input, and an output, wherein the first input is connected to the output of the latch, the resect input is connected to the output of the first transition detector, and the clock input is configured to receive a clock signal; and

a second latch having a first input, a second input, and an output, wherein the first input is connected to the output of the counter, wherein the second input is connected to tile output of the counter, and wherein the output generates a delay value.

39. The delay channel apparatus of claim 31, wherein the delay adjustment unit includes a plurality of delay units, wherein each delay unit is associated within a data channel within the plurality of data channels and wherein each delay unit includes a set of delay cells in which each delay cell contains at least one delay client.

40. The delay channel apparatus of claim 31, wherein each delay unit includes a two delay elements.

41. The delay channel apparatus of claim 38, wherein a ring oscillator circuit generates a clock signal for application to tic clock input in the counter.

42. A data processing system for managing reception of data signals on a plurality of data lines, the data processing system comprising:

reciving means for receiving data signals on the plurality of data lines and a reference signal;

measuring means for measuring a delay between the data signal and the reference signal on each of the plurality of data lines, based on a periodic timing reference to form a plurality of delay measurements;

generating means for generating a set of delay values from the plurality of delay measurements; and

using means for using the set or delay values to adjust delay in a reception in each of the plurality of data signals in the plurality of data lies.

43. The data processing system of claim 42, wherein a delay value is selected for a data line in the plurality of data lines to, adjust a delay for the data line to a slowest data line within the plurality of data lines.

44. The data processing system of claim 42, wherein the plurality of data lines are in a small computer system interface bus.

45. The data processing system of claim 42, wherein the plurality of data lines is sixteen.

46. The data processing system of claim 42, wherein the delay in a data line within the plurality of data lines is implemented using a delay chain.

47. The data processing system of claim 42, wherein the receiving mains, measuring means, and generating means are initiated in response to a command from a host device.

48. The data processing system of claim 42, wherein the receiving means, measuring means, and generating means are initiated periodically and changes in delay caused by temperature changes are minimized.

49. The data processing system of claim 42, wherein the reference signal is an acknowledgment signal.

50. The data processing system of claim 42, wherein the measuring means is accomplished using a delay counter.

51. Tie data processing system of claim 42, wherein the data signal is a test signal.

52. The data processing system of claim 42, wherein the plurality of data lines requires a different delay value.

53. The data processing system of claim 42, wherein the generating means:

identifying means for identifying a data line within the plurality of data lines having a longest delay within the plurality of delay measurements; and

selecting means for selecting delay values for other data lines within the plurality of delay lines, wherein the delay values set the delay for the other data lines equal to the data line.

54. The data processing system of claim 53 further comprising:

second selecting means for selecting a delay value for the reference signal, wherein the adjusted delay value causes transitions in the data signals received from the plurality of lines to occur during a middle of a pulse for the reference signal.

55. The data processing system of claim 42, wherein the generating means:

identifying means for identifying a largest delay within the set of delay values;

selecting means for selecting delay value for each of the plurality of data lines equal to the largest delay minutes the delay for each of the data line plurality of data lines.

56. Tho data processing system of claim 42, wherein the receiving means, measuring means, and generating means are located in a target device.

57. The data processing system of claim 42, wherein the receiving means, measuring means, and generating, means are located in a host device.

58. A data processing system for equalizing a reception of data signals in a plurality of input channels in a device, tie data processing system comprising:

receiving means for receiving a data signal form each of the plurality of input channels in the device and a reference signal;

identifying means for identifying a delay between a transition in the data signal and a transition in the reference signal on each channel of the plurality of input channels, based on a periodic timing reference, to form a plurality of delays; and

using means for using the plurality of delays to adjust a delay in a reception of a data signal on each channel within the set of input channels to increase a setup and a hold time for the plurality of data signals.

59. The data processing system of claim 58, wherein the reference signal is an acknowledgment signal.

60. The data processing system of claim 58, wherein the plurality of input channels lines are in a small computer system interface device.

61. The data processing system of claim 58, wherein the plurality of input channels is sixteen.

62. The data processing system of claim 58, wherein the receiving means and identifying means are initiated in response to a signal from a host device.

63. The data processing system of claim 58, wherein the receiving means and identifying means are initiated periodically.

64. The data processing system of claim 58, wherein the delay in an input channel within the plurality of input channels is implemented using a plurality of delay structures.

65. A computer program product in a computer readable medium for managing transmission of data signals on plurality of data lines, the computer program product comprising:

first instructions for receiving data signals on the plurality of data lines and a reference signal;

second instructions for measuring a delay between the data signal and the reference signal on each of the plurality of data lines, based on a periodic timing reference, to form a plurality of delay measurements;

third instructions for generating a set of delay values from the plurality of delay measurements; and

fourth instructions for using the set of delay values to adjust delay in a transmission in each of the plurality of data signals in the plurality of data lines.

66. A computer program product in a computer readable medium for equalizing a transmission of data signals in a plurality of input channels in a device, the computer program product comprising:

first instructions for receiving a data signal form each of the plurality of input channels in the device and a reference signal;

second instructions for identifying a delay between a transition in the data signal and a transition in the reference signal on each channel of the plurality of input channels, based on a periodic timing reference to form a plurality of delays; and

third instructions for using the plurality of delays to adjust a delay in a transmission of a data signal on each channel within the set of input channels to increase a setup and a hold time for the plurality of data signals.