Speed signaling for data communications

• US 6,731,688 B1
• Filed: 12/13/1999
• Issued: 05/04/2004
• Est. Priority Date: 12/13/1999
• Status: Expired due to Term

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Johnson, Luke A.
• Primary Examiner(s): Le, Amanda T.
• Application Number:
  US09/459,274
• Time in Patent Office: 1,604 Days
• Field of Search: 375/219, 375/220, 375/222, 375/224, 375/225, 375/288, 375/259, 375/257, 375/258, 370/468
• US Class Current: 375/257
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: Y02D 30/50 in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

Communications between a host and a peripheral may be initiated by the peripheral transmitting data at the highest support data rate to the host. If the host is able to recognize the data, the host can so indicate to the peripheral. Otherwise, the peripheral may try a lower data rate progressively decreasing the data rate until the best possible data rate is identified under current conditions. In this way, a communication link may be established in a relatively straightforward fashion that is optimal for the given current conditions.

Claims

1. A method comprising:

transmitting a predetermined data pattern to a receiver at a first data rate;

if the receiver does not recognize the pattern, transmitting the pattern at a second data rate that is lower than the first data rate; and

establishing communications by transmitting signals in a format different than the format utilized for communications including transmitting three different voltage levels including a lower level, an intermediate level, and a higher level.

2. The method of claim 1 including initiating a power on sequence by transmitting the intermediate level followed by the higher level.

3. The method of claim 2 including transitioning from the intermediate level to the higher level in response to receipt of a signal that transitions from the lower level to the higher level.

4. The method of claim 3 including transmitting a calibration sequence in response to the receipt of the higher level.

5. The method of claim 4 including transmitting the lower level followed by a calibration sequence.

6. The method of claim 5 including transmitting the lower level after transmitting a calibration sequence after receiving the lower level.

7. The method of claim 1 including receiving said data pattern and returning said data pattern at the same rate as the pattern was received.

8. The method of claim 7, wherein if a received data pattern is not recognized, transmitting a characteristic voltage level.

9. The method of claim 8 including waiting for a receiver to transition from the low level for a predetermined time, and after the time is expired, transmitting a pattern at a second data rate that is lower than the first data rate.

10. A method comprising:

receiving a predetermined data pattern at a first data rate;

determining whether the pattern is recognized; and

if the pattern is not recognized, requesting that the pattern be retransmitted at a second data rate that is lower than the first data rate and providing an out of band signal that is sent by a different means than a normal transmission transmitting a characteristic voltage level.

11. The method of claim 10 including receiving said data pattern and returning said data pattern at the same rate as the pattern was received.

12. A method comprising:

transmitting a predetermined data pattern to a receiver at a first data rate;

if the receiver does not recognize the pattern, transmitting the pattern at a second data rate that is lower than the first data rate;

establishing communications by transmitting three different voltage levels including a lower level, an intermediate level, and a higher level; and

initiating a power on sequence by transmitting the intermediate level followed by the higher level.

13. The method of claim 12 including transitioning from the intermediate level to the higher level in response to receipt of a signal that transitions from the lower level to the higher level.

14. The method of claim 13 including transmitting a calibration sequence in response to the receipt of the higher level.

15. The method of claim 14 including transmitting the lower level followed by a calibration sequence.

16. The method of claim 15 including transmitting the lower level after transmitting a calibration sequence after receiving the lower level.