De-emphasis training on a point-to-point connection

• US 7,502,338 B1
• Filed: 12/19/2003
• Issued: 03/10/2009
• Est. Priority Date: 12/19/2003
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Whitby-Strevens, Colin
• Primary Examiner(s): Ngo; Ricky
• Assistant Examiner(s): Liu; Ben H
• Application Number:
  US10/742,719
• Time in Patent Office: 1,908 Days
• Field of Search: 370/338, 370/229, 370331-334, 370/401, 370/282, 370/292, 375/219, 375/295, 375/316
• US Class Current: 370/292
• CPC Class Codes: H04B 1/62 for providing a predistortion of the signal in the transmitter and corresponding correction in the receiver, e.g. for improving the signal/noise ratio
• CPC Class Codes: H04B 3/145 variable equalisers

Abstract

A method for establishing data transmission between a two devices by performing de-emphasis training is disclosed. While a retry count does not exceed a predetermined threshold: a training pattern with a signal strength is sent from a first device to a second device. If a negative acknowledgement is received from the second device within enough time to determine that the send training pattern was unacceptable to the second device, the retry count is incremented, the signal strength for the training pattern is attenuated and the training pattern is resent.

Claims

1. A method for establishing data transmission between two devices by performing de-emphasis training, the method comprising:

while a retry count does not exceed a predetermined threshold;

sending with a signal strength a training pattern from a first device to a second device;

receiving negative acknowledgement from the second device within enough time to determine that the sent training pattern was unacceptable to the second device;

incrementing a retry count; and

attenuating the signal strength; and

if the retry count exceeds the predetermined threshold, then perform remedial action to improve data transmission between the first and second devices.

2. The method of claim 1, wherein the negative acknowledgement is derived from evaluating an eye pattern derived from a data stream received by the second device, the data stream approximating the transmitted training pattern.

3. The method of claim 1, wherein the remedial action performed comprises slowing a transmission speed between the two devices.

4. The method of claim 1, wherein the remedial action performed comprises reporting a failure to a device management software.

5. The method of claim 1, wherein the remedial action performed comprises triggering a timeout condition.

6. The method of claim 1, wherein the negative acknowledgement comprises a pattern of alternating bit values.

7. The method of claim 1, wherein the negative acknowledgement comprises a pattern without high frequency content.

8. The method of claim 6, wherein the negative acknowledgement comprises a number of a first bit followed by the same number of a second bit, the second bit opposite from the first bit.

9. A method for establishing data transmission between two devices by performing de-emphasis training, the method comprising:

while a training pattern counter does not exceed a predetermined threshold;

sending a training pattern from a first device to a second device;

verifying the absence of a negative acknowledgement sent from the second device;

incrementing a training pattern counter; and

modifying the training pattern.

10. The method of claim 9, wherein the act of modifying the training pattern comprises lengthening the training pattern.

11. A method for establishing data transmission between two devices by performing de-emphasis training, the method comprising:

while a training pattern counter does not exceed a predetermined threshold;

sending a training pattern from a first device to a second device;

verifying the absence of a negative acknowledgement sent from the second device;

incrementing a training pattern counter; and

modifying the training pattern.

12. The method of claim 11, wherein the negative acknowledgement is derived from evaluating an eye pattern derived from a data stream received by the second device, the data stream approximating the transmitted training pattern.

13. The method of claim 11, further comprising performing a remedial action if the training pattern counter exceeds the predetermined threshold, said remedial action comprising slowing a transmission speed between the two devices.

14. The method of claim 11, further comprising performing a remedial action if the training pattern counter exceeds the predetermined threshold, said remedial action comprising reporting a failure to a device management software.

15. The method of claim 11, further comprising performing a remedial action if the training pattern counter exceeds the predetermined threshold, said remedial action comprising triggering a timeout condition.

16. The method of claim 11, wherein the negative acknowledgement comprises a pattern of alternating bit values.

17. The method of claim 11, wherein the negative acknowledgement comprises a pattern without high frequency content.

18. The method of claim 17, wherein the negative acknowledgement comprises a number of a first bit followed by the same number of a second bit, the second bit opposite from the first bit.

19. The method of claim 11, wherein the act of modifying the training pattern comprises lengthening the training pattern.

20. A method of establishing data transmission between two devices by performing de-emphasis training, the method comprising:

a) performing speed negotiation between a first device and a second device;

b) synchronizing the first and second devices;

c) selecting a de-emphasis training pattern and de-emphasis level;

d) until all de-emphasis training patterns to be sent from the first device to the second device are sent;

1) until all de-emphasis levels to be tried for a given training pattern have not been sent from the first device to the second device;

i) transmitting the de-emphasis pattern from the first device to the second device at the selected de-emphasis level;

ii) analyzing an incoming bit stream to determine signal quality;

iii) changing de-emphasis level for the training pattern; and

iv) resending the training pattern with the changed de-emphasis level;

2) changing the de-emphasis pattern to be sent;

e) setting an acceptable de-emphasis level based on the analyzed bit streams; and

f) transmitting symbols from the first device to the second device using the acceptable de-emphasis level.

21. The method of claim 20, wherein the de-emphasis level selected in act c) comprises no de-emphasis.

22. The method of claim 20, wherein the act of synchronizing comprises sending a synchronizing training pattern from the first device to the second device.

23. The method of claim 20, wherein the act of analyzing the incoming bit stream comprises:

applying a margin to a receiver on the first device, the receiver receiving the incoming bit stream; and

evaluating signal quality of the incoming bit stream received by the receiver.

24. A method of establishing data transmission between two devices by performing de-emphasis training, the method comprising:

a) performing speed negotiation between a first device and a second device;

b) synchronizing the first and second devices;

c) selecting a de-emphasis training pattern and de-emphasis level;

d) until all de-emphasis training patterns to be sent from the first device to the second device are sent;

1) until all de-emphasis levels to be tried for a given training pattern have not been sent from the first device to the second device;

i) transmitting the de-emphasis pattern from the first device to the second device at the selected de-emphasis level;

ii) analyzing an incoming bit stream to determine signal quality;

iii) unless the analysis identifies an acceptable de-emphasis level, changing de-emphasis level for the training pattern and resending the training pattern with the changed de-emphasis level;

2) resetting the de-emphasis level changing the de-emphasis pattern to be sent;

e) setting an acceptable de-emphasis level based on the analyzed bit streams; and

f) transmitting symbols from the first device to the second device using the acceptable de-emphasis level.

25. The method of claim 24, wherein the de-emphasis level selected in act c) comprises no de-emphasis.

26. The method of claim 24, wherein the act of synchronizing comprises sending a synchronizing training pattern from the first device to the second device.

27. The method of claim 24, wherein the act of analyzing the incoming bit stream comprises:

applying a margin to a receiver on the first device, the receiver receiving the incoming bit stream; and

evaluating signal quality of the incoming bit stream received by the receiver.

28. A method for establishing data transmission between devices by de-emphasis training, the method comprising:

sending with a signal strength a training pattern from a first device to a second device;

receiving information from the second device, the information indicative that the sent training pattern was unacceptable to the second device;

incrementing a retry count;

reducing the signal strength; and

when the retry count exceeds the predetermined threshold, performing remedial action to improve data transmission between the first and second devices.

29. A method for establishing data transmission between devices by de-emphasis training, the method comprising:

while a counter does not exceed a predetermined threshold;

sending a training pattern from a first device to a second device;

determining the absence of information sent from the second device, said information indicating that the sent training pattern was unacceptable to the second device;

incrementing said counter; and

based at least in part on said determining the absence, modifying the training pattern.

30. A method of establishing data transmission between devices via de-emphasis training, the method comprising:

selecting a first de-emphasis training pattern to be sent between a first device and a second device;

transmitting the de-emphasis pattern from the first device to the second device at a first selected de-emphasis level;

analyzing an incoming bit stream associated with said transmitted pattern to determine signal quality;

changing the de-emphasis level for the training pattern based at least in part on said analyzing;

resending the training pattern with the changed de-emphasis level; and

repeating said acts of analyzing, changing and resending at different de-emphasis levels so as to identify and acceptable de-emphasis level based on the analyzed bit streams; and

transmitting symbols from the first device to the second device using the acceptable de-emphasis level.