METHOD FOR ROBUST PREAMBLE LOCATION IN A DQS SIGNAL

• US 20130208553A1
• Filed: 02/10/2012
• Published: 08/15/2013
• Est. Priority Date: 02/10/2012
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: LSI Corporation (Broadcom, Inc.)
• Inventors: Hunt, Brandon L., Fry, Michael S.
• Granted Patent: US 8,773,926 B2
• Time in Patent Office: Days
• US Class Current: 365/193
• CPC Class Codes: G11C 11/40 using transistors
• CPC Class Codes: G11C 2207/2254 Calibration
• CPC Class Codes: G11C 29/023 in clock generator or timing circuitry
• CPC Class Codes: G11C 29/028 with adaption or trimming of parameters
• CPC Class Codes: G11C 7/1066 Output synchronization

Abstract

A method for robust preamble location and gate training in a Double Data Rate type Three (DDR3) computing environment. A single algorithm is employed to begin sampling a Data Strobe Signal (DQS) at a maximum delay value designed to fall within the driven region of a DQS. The method then begins sampling the DQS in a sequence of delay values from right to left. Each result of the sampling indicating a high state and a low state are stored as well as the occasions where the DQS transitioned from high to low indicating a rising edge. At a consecutive number of samples returning a low state, the method determines the preamble has been reached and discontinues sampling. The method retains the most recently stored rising edge as the first rising edge and configures the result for gate training.

Claims

1. A method for capturing a Data Lane Signal (DQ) by determining a preamble location in a Data Strobe Signal (DQS), comprising:

using a computer device or processor to perform the steps of;

receiving a maximum delay value and a step size;

sampling said DQS at said maximum delay value;

sampling said DQS in a sequence of delay values, a greatest delay value in said sequence of delay values being one step size less than said maximum delay value, each delay value of said sequence of delay values being one step size less than a proximal delay value, said sequence of delay values beginning with said greatest delay value;

storing at least one delay value when said sampling indicates said DQS was at a high;

storing at least one delay value when said sampling indicates said DQS was at a low;

storing at least one delay value when said sampling indicates said DQS made a transition from said high to said low;

determining and storing an earliest location of said transition from said high to said low;

storing a preamble location and discontinuing said sampling when, during a single clock cycle, said sampling indicates a number of consecutive instances of said DQS being at said low, said number of consecutive instances based on a multiple of said step size; and

capturing a DQ based on said stored preamble location and said earliest location of said transition from said high to said low.

2. The method of claim 1, wherein said receiving a maximum delay value and a step size from further comprises an analysis of at least three of:

a. a range of delays for a specific memory system;

b. a latency value of a column to address strobe (CAS);

c. a hardware constant;

d. a frequency of a memory clock; and

e. a determination if a register is located between a SDRAM and a controller.

3. The method of claim 1, wherein said maximum delay value is a range.

4. The method of claim 1, wherein said step size is variable by at least one of said computer device, said processor, and a user.

5. The method of claim 1, wherein said sequence of delay values is non-linear.

6. The method of claim 1, wherein said sampling said DQS in a sequence of delay values further, a greatest delay value in said sequence of delay values being one step size less than said maximum delay value, each delay value of said sequence of delay values being one step size less than a proximal delay value, said sequence of delay values beginning with said greatest delay value further comprises repeat operations using said maximum delay value and said step size.

7. The method of claim 1, wherein storing at least one delay value when said sampling indicates said DQS made a transition from said high to said low further includes storing a result configured for gate training.

8. The method of claim 1, wherein said sampling is configured to ignore results received from a sampling of a DQS in a tri-stated region.

9. The method of claim 1, wherein said multiple is 2 or greater.

10. The method of claim 1, wherein results of said sampling are configured for gate training.

11. A method for gate training in a Double Data Rate type Three (DDR3) environment and for simultaneously determining a location of a preamble in a plurality of Data Strobe Signals (DQS) across a corresponding plurality of data lanes, the method comprising:

using a computer device or processor to perform the steps of;

receiving a maximum delay value and a step size;

sampling said plurality of DQS at said maximum delay value;

sampling, concurrently and in parallel, said plurality of DQS in a sequence of delay values, a greatest delay value in said sequence of delay values being one step size less than said maximum delay value, each delay value of said sequence of delay values being one step size less than a proximal delay value, said sequence of delay values beginning with said greatest delay value;

storing at least one delay value when said sampling indicates said DQS was at a high;

storing at least one delay value when said sampling indicates said DQS was at a low;

storing at least one delay value when said sampling indicates said DQS made a transition from said high to said low;

determining and storing an earliest location of said transition from said high to said low;

training a series of gates corresponding to said plurality of data lanes based on a result of said determining and storing an earliest location of said transition;

storing a preamble location and discontinuing said sampling for each of said plurality of DQS when, during a single clock cycle, said sampling indicates a number of consecutive instances of said DQS being at said low, said number of consecutive instances based on a multiple of said step size; and

capturing, concurrently and in parallel, a plurality of Data Signals (DQ) based on said stored preamble location and said earliest location of said transition from said high to said low.

12. The method of claim 11, wherein said receiving a maximum delay value and a step size further comprises an analysis of at least three of:

a. a range of delays for a specific memory system;

b. a latency value of a column to address strobe (CAS);

c. a hardware constant;

d. a frequency of a memory clock; and

e. a determination if a register is located between a SDRAM and a controller.

13. The method of claim 11, wherein said maximum delay value is at least one of a range, a fixed delay value for all of said plurality of data lanes, and a unique delay value for each individual data lane of said plurality of data lanes.

14. The method of claim 11, wherein said step size is variable by at least one of said computer device, said processor, and a user.

15. The method of claim 11, wherein said sequence of delay values is non-linear.

16. The method of claim 11, wherein said sampling, concurrently and in parallel, said plurality of DQS in a sequence of delay values, a greatest delay value in said sequence of delay values being one step size less than said maximum delay value, each delay value of said sequence of delay values being one step size less than a proximal delay value, said sequence of delay values beginning with said greatest delay value further comprises repeat operations using said maximum delay value and said step size.

17. The method of claim 11, wherein storing at least one delay value when said sampling indicates said DQS made a transition from said high to said low further includes storing a result configured for gate training.

18. The method of claim 11, wherein said sampling is configured to ignore results received from a sampling of a DQS in a tri-stated region.

19. The method of claim 11, wherein said multiple is 2 or greater.

20. The method of claim 11, wherein results of said sampling are configured for a gate training session.