Reducing precision timing measurement uncertainty

• US 9,946,683 B2
• Filed: 12/24/2014
• Issued: 04/17/2018
• Est. Priority Date: 12/24/2014
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Froelich, Daniel, Harriman, David J.
• Primary Examiner(s): Myers, Paul R
• Application Number:
  US14/582,734
• Publication Number:
  US 20160188524A1
• Time in Patent Office: 1,210 Days
• Field of Search: 710301
• CPC Class Codes: G06F 13/4059 where the synchronisation uses buffers, e.g. for speed matching between buses
• CPC Class Codes: G06F 13/4286 using a handshaking protocol, e.g. RS232C link

Abstract

Techniques for reducing precision timing message uncertainty are described herein. A method includes resetting an elastic buffer of a first device in response to a second device linked with the first device sending SKIP (SKP) ordered sets to the first device. The method also includes initiating a PTM handshake with the second device in response to resetting the elastic buffer. Additionally, the method includes sending PTM messages to the second device immediately after receiving the SKP ordered sets.

Claims

1. A method for reducing precision timing measuring (PTM) uncertainty, the method comprising:

sending SKIP (SKP) ordered sets to a first device comprising an elastic buffer in order to ensure the elastic buffer is reset at a consistent location before initiating a precision timing measurement (PTM) handshake; and

initiating the PTM handshake with the first device after sending the SKP ordered sets.

2. The method of claim 1, comprising:

determining an average interval of the SKP ordered sets; and

synchronizing transmission of the SKP ordered sets to an expected time based on the average interval.

3. The method of claim 1, comprising:

determining that it is time to initiate a PTM handshake; and

sending the SKP ordered sets in response to the determination.

4. The method of claim 1, wherein resetting the elastic buffer comprises setting the elastic buffer at a neutral position.

5. The method of claim 4, the neutral position comprising a halfway point of the elastic buffer.

6. The method of claim 1, comprising generating a pulse from a reference clock indicating it is a time to initiate the PTM handshake.

7. The method of claim 6, comprising generating the pulse at a same phase of multiple cycles for a spread spectrum clock in a separate reference clock with independent spread (SRIS) architecture.

8. An apparatus for reducing precision timing message uncertainty between linked devices, the apparatus comprising:

an elastic buffer; and

a memory comprising logic to;

send SKIP (SKP) ordered sets to a first device comprising an elastic buffer in order to ensure the elastic buffer is reset at a consistent location before initiating a precision timing measurement (PTM) handshake; and

initiate a PTM handshake with the first device after sending the SKP ordered sets.

9. The apparatus of claim 8, the memory comprising logic to:

determine an average interval of the SKP ordered sets; and

synchronize transmission of the SKP ordered sets to an expected time based on the average interval.

10. The apparatus of claim 8, the memory comprising logic to:

determine that it is time to initiate a PTM handshake; and

send the SKP ordered sets in response to the determination.

11. The apparatus of claim 8, wherein the elastic buffer is reset by setting the elastic buffer at a neutral position.

12. The apparatus of claim 11, the neutral position comprising a halfway point of the elastic buffer.

13. The apparatus of claim 8, the memory comprising logic to generate a pulse from a reference clock indicating it is a time to initiate the PTM handshake.

14. The apparatus of claim 13, the memory comprising logic to generate the pulse at a same phase of multiple cycles for a spread spectrum clock in a separate reference clock with independent spread (SRIS) architecture.

15. The apparatus of claim 8, comprising a processor.

16. A system for reducing precision timing message uncertainty, the system comprising:

a receiver device comprising an elastic buffer; and

a transmitter device linked with the receiver device, the transmitter device comprising;

a transmitter reference clock;

a transmitter memory comprising logic to;

send a series of SKIP (SKP) ordered sets to the receiver device in order to ensure the elastic buffer is reset to a consist location before initiating a precision timing measurement (PTM) handshake with the receiver device; and

initiate the PTM handshake after the series of SKP ordered sets are sent.

17. The system of claim 16, the transmitter memory comprising logic to:

determine an average interval of the SKP ordered sets; and

synchronize transmission of the SKP ordered sets to an expected time based on the average interval.

18. The system of claim 16, the transmitter memory comprising logic to:

determine that it is time to initiate a PTM handshake; and

send the SKP ordered sets in response to the determination.

19. The system of claim 16, wherein the elastic buffer is reset by setting the elastic buffer at a neutral position.

20. The system of claim 19, the neutral position comprising a halfway point of the elastic buffer.

21. The system of claim 16, the transmitter memory comprising logic to generate a pulse from the transmitter reference clock indicating it is the time to initiate the PTM handshake.

22. The system of claim 21, the transmitter memory comprising logic to generate the pulse at a same phase of multiple cycles for a spread spectrum clock in a separate reference clock with independent spread (SRIS) architecture.