Method and apparatus for scrambling data for control of high-speed bidirectional signaling

• US 7,929,549 B1
• Filed: 03/06/2006
• Issued: 04/19/2011
• Est. Priority Date: 03/06/2006
• Status: Active Grant

• Current Assignee: Advanced Micro Devices, Inc.
• Original Assignee: Advanced Micro Devices, Inc.
• Inventors: Talbot, Gerald R.
• Primary Examiner(s): Moe; Aung S
• Assistant Examiner(s): Mered; Habte
• Application Number:
  US11/368,786
• Time in Patent Office: 1,870 Days
• Field of Search: 370/431, 370/441, 370/515, 370/440, 380/268, 380/255, 380/259, 380/264, 380/28, 380 44- 46, 713/100, 713182-193, 375259-268, 711/1, 711/100, 711/163, 711/164, 711/173, 711203-209, 711216-217, 711/E12.092, 726/16
• US Class Current: 370/395.7
• CPC Class Codes: H04L 12/40013 Details regarding a bus controller
• CPC Class Codes: H04L 9/0662 with particular pseudorandom sequence generator

Abstract

A memory subsystem includes a master controller that includes a pseudo random bit sequence (PRBS) generator having a plurality of output taps and an exclusive-OR (XOR) unit. The memory subsystem also includes a memory device that is coupled to the master controller via a plurality of single ended bidirectional data paths. The master controller may scramble a plurality of data bits using the PRBS generator and the XOR unit prior to writing the plurality of data bits to the memory device. In addition, the master controller may perform an XOR between each bit of the plurality of data bits and a respective output tap of the PRBS generator prior to conveyance on a respective path of the plurality of single ended bidirectional data paths.

Claims

1. A memory subsystem comprising:

a master controller including a pseudo random bit sequence (PRBS) generator having a plurality of output taps and an exclusive-OR (XOR) unit, wherein each output tap of the PRBS generator provides a different bit sequence; and

a memory device coupled to the master controller via a plurality of single ended bidirectional data paths, wherein each data path conveys a respective plurality of data bits;

wherein the master controller is configured to scramble each respective plurality of data bits using the PRBS generator and the XOR unit prior to writing each respective plurality of data bits to the memory device;

wherein for each of the plurality of single ended bidirectional data paths, the master controller is configured to perform an XOR operation between each bit of the respective plurality of data bits and each bit provided by a respective output tap of the PRBS generator prior to conveyance on a corresponding data path of the plurality of single ended bidirectional data paths; and

wherein the memory device further includes a control register including a plurality of bit positions, each having a default logic sense definition, wherein the bit position default logic sense definition of one or more bit positions are adaptively modified such that a logic value of one is sensed as an asserted bit prior to modification, and sensed as a deasserted bit after modification dependent upon a value to be stored within the control register.

2. The memory subsystem as recited in claim 1, wherein the memory device is configured to store each respective plurality of data bits in a scrambled state at one or more locations.

3. The memory subsystem as recited in claim 2, wherein the master controller is further configured to descramble each respective plurality of data bits that have been scrambled and which have been returned from the memory device in response to the master controller performing a read operation using a scrambling seed used for scrambling each respective plurality of data bits.

4. The memory subsystem as recited in claim 3, wherein the master controller is further configured to generate the scrambling seed by preloading the PRBS unit with the address of the one or more locations to be accessed and shifting the PRBS unit a predetermined number of stages.

5. A method comprising:

a master controller writing a respective plurality of data bits on each of a plurality of single ended bidirectional data paths for storage in a memory device, wherein the master controller includes a pseudo random bit sequence (PRBS) generator having a plurality of output taps and an exclusive-OR unit (XOR);

the PRBS generator generating a different bit sequence on each output tap;

the master controller scrambling each respective plurality of data bits using the PRBS generator and the XOR unit prior to the master controller writing each respective plurality of data bits;

the master controller performing, for each of the plurality of single ended bidirectional data paths, an XOR operation between each bit of the respective plurality of data bits and each bit provided by a respective output tap of the PRBS generator prior to conveyance on a corresponding data path of the plurality of single ended bidirectional data paths; and

the master controller adaptively modifying a bit position default logic sense definition of one or more bit positions of a control register of the memory device dependent upon a value to be stored within the control register such that a logic value of one is sensed as an asserted bit prior to modification, and sensed as a deasserted bit after modification, wherein the control register includes a plurality of bit positions, each having the default logic sense definition.

6. The method as recited in claim 5, further comprising the memory device storing each respective plurality of data bits in a scrambled state at one or more locations within the memory device.

7. The method as recited in claim 6, further comprising the master controller descrambling each respective plurality of data bits that have been scrambled and which have been returned from the memory device in response to the master controller performing a read operation using a scrambling seed used for scrambling each respective plurality of data bits.

8. The method as recited in claim 7, further comprising the master controller generating the scrambling seed by preloading the PRBS generator with the address of the one or more locations to be accessed and shifting the PRBS unit a predetermined number of stages.

9. A system comprising:

a master device including a first pseudo random bit sequence (PRBS) generator having a plurality of output taps and a first exclusive-OR (XOR) wherein each output tap of the PRBS generator provides a different bit sequence; and

a slave device coupled to the master device via a plurality of single ended bidirectional data paths, wherein each data path conveys a respective plurality of data bits, wherein the slave device includes a second PRBS generator and a second XOR unit, wherein the second PRBS generator is substantially the same as the first PRBS generator;

wherein the master device is configured to scramble each respective plurality of data bits using the first PRBS generator and the first XOR unit prior to sending each respective plurality of data bits to the slave device;

wherein the slave device is configured to descramble each respective plurality of data bits using the second PRBS generator and the second XOR unit;

wherein the first PRBS generator and the second PRBS generator are synchronized to generate a same sequence; and

wherein the slave device further includes a control register including a plurality of bit positions, each having a default logic sense definition, wherein the master device is configured to adaptively modify the control register bit position default logic sense definition of one or more bit positions such that a logic value of one is sensed as an asserted bit prior to modification, and sensed as a deasserted bit after modification, dependent upon a value to be stored within the control register.

10. The system as recited in claim 9, wherein the master device is configured to send a synchronization command to the slave device during an initialization.

11. The system as recited in claim 9, wherein for each of the plurality of single ended bidirectional data paths, the master device is configured to perform an XOR operation between each bit of the respective plurality of data bits and each bit provided by a respective output tap of the first PRBS generator prior to conveyance on a corresponding data path of the plurality of single ended bidirectional data paths.

12. The system as recited in claim 9, wherein the slave device is configured to scramble each respective plurality of data bits using the second PRBS generator and the second XOR unit prior to sending each respective plurality of data bits to the master device.

13. The system as recited in claim 9, wherein the master device is configured to descramble each respective plurality of data bits using the first PRBS generator and the first XOR unit, wherein the first PRBS generator and the second PRBS generator are synchronized to generate a same sequence.