Polarity detection system

• US 9,253,072 B2
• Filed: 10/23/2013
• Issued: 02/02/2016
• Est. Priority Date: 10/24/2012
• Status: Expired due to Fees

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Lin, Xiaotong, Tazebay, Mehmet Vakif
• Primary Examiner(s): Ferris, Derrick
• Assistant Examiner(s): VOGEL, JAY L.
• Application Number:
  US14/060,980
• Publication Number:
  US 20140112176A1
• Time in Patent Office: 832 Days
• US Class Current: 1/1
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 1/242 by comparing a transmitted test signal with a locally generated replica
• CPC Class Codes: H04L 43/50 Testing arrangements
• CPC Class Codes: H04L 5/1438 Negotiation of transmission parameters prior to communication modified according to link quality H04L1/0001
• CPC Class Codes: H04L 5/16 Half-duplex systems; Simplex/duplex switching; Transmission of break signals non-automatically inverting the direction of transmission

Abstract

In the subject system for polarity detection, link initialization between a primary device and a secondary device may be performed in at least two stages, a half-duplex stage when only the primary device transmits initialization signals and any encoded handshaking signals may be set to false, and a full-duplex stage when both devices may transmit initialization signals. The secondary device may perform polarity detection during the half-duplex stage. If the secondary device determines that the polarities of the received signals are reversed, the secondary device may reverse the polarities of any signals subsequently received from, and transmitted to, the primary device. In this manner, the polarities can be corrected for both devices during the half-duplex stage by the secondary device. The secondary device may initiate the full-duplex link initialization stage, during which any handshaking signals may be exchanged, by transmitting signals to the primary device.

Claims

1. A method for polarity detection, the method comprising:

receiving, by a secondary device, a first signal and a second signal from a primary device during a half-duplex stage of a link initialization;

determining, during the half-duplex stage, whether a descrambler of the secondary device can be locked to a scrambler of the primary device using at least the first signal or the first signal with a first polarity reversed;

changing, during the half-duplex stage, a symbol boundary associated with the first signal when the descrambler cannot be locked using at least the first signal or the first signal with the first polarity reversed;

determining, during the half-duplex stage of the link initialization, whether the first polarity of the first signal and a second polarity of the second signal are reversed based at least on whether the descrambler can be locked using at least the first signal or the first signal with the changed symbol boundary; and

reversing, by the secondary device, polarities of signals subsequently received from, and transmitted to, the primary device when the first polarity of the first signal and the second polarity of the second signal are reversed.

2. The method of claim 1, wherein a handshaking signal that is encoded by the first signal and the second signal is set to false.

3. The method of claim 2, wherein determining, during the half-duplex stage of the link initialization, whether the first polarity of the first signal and the second polarity of the second signal are reversed further comprises determining, during the half-duplex stage of the link initialization and based at least on the handshaking signal and whether the descrambler can be locked using at least the first signal or the first signal with the first polarity reversed, whether the first polarity of the first signal and the second polarity of the second signal are reversed.

4. The method of claim 1, further comprising:

determining a third polarity of a third signal and a fourth polarity of a fourth signal based at least on whether the first polarity of the first signal and the second polarity of the second signal are reversed; and

initiating a full-duplex stage of the link initialization by transmitting the third signal and the fourth signal to the primary device.

5. The method of claim 4, further comprising:

receiving a fifth signal and sixth signal from the primary device; and

determining a fifth polarity of the fifth signal and a sixth polarity of the sixth signal based at least on whether the first polarity of the first signal and the second polarity of the second signal are reversed.

6. The method of claim 1, wherein the secondary device is communicably coupled to the primary device via a single twisted pair of wires, the first signal is received over a first wire of the single twisted pair of wires and the second signal is received over a second wire of the single twisted pair of wires.

7. The method of claim 1, wherein the symbol boundary delineates individual symbols.

8. The method of claim 7, further comprising:

changing the symbol boundary associated with the first signal and the second signal; and

determining whether the descrambler of the secondary device can be locked to the scrambler of the primary device based at least on the reversed first polarity of the first signal and the changed symbol boundary.

9. The method of claim 1, further comprising:

receiving a clock source from the primary device for the link initialization.

10. A communication device comprising:

a physical coding sublayer module comprising;

a descrambler that is configurable to synchronize with a scrambler of another communication device; and

a polarity corrector that is configurable to reverse polarities of symbols transmitted to and received from the another communication device; and

wherein the physical coding sublayer module is configured to;

receive a clock source from the another communication device for link initialization, receive, during a half-duplex link initialization stage, first training symbols having a first polarity and second training symbols having a second polarity, determine, during the half-duplex stage, whether the descrambler can be locked to the scrambler of the another device based at least on the first training symbols, reverse the first polarity of the first training symbols or change a symbol boundary associated with the first training symbols and the second training symbols during the half-duplex link initialization stage when the descrambler is unable to be locked using at least the first training symbols,

synchronize, during the half-duplex link initialization stage, the descrambler to the scrambler of the another communication device based on at least one of the reversed first polarity associated with the first training symbols or the changed symbol boundary of the first training symbols when the descrambler is unable to be locked using at least the first training symbols, and

configure the polarity corrector to reverse the symbols subsequently transmitted to, and received from the another communication device when the descrambler is synchronized based at least on the reversed first polarity associated with the first training symbols.

11. The communication device of claim 10, wherein the physical coding sublayer module further comprises a memory that stores a value of a handshaking signal encoded by the first and second symbols during the half-duplex link initialization stage.

12. The communication device of claim 11, wherein the physical coding sublayer module is further configured to:

synchronize, during the half-duplex link initialization stage, the descrambler to the scrambler of the another communication device based at least on the stored value of the handshaking signal and the reversed first polarity associated with the first symbols.

13. The communication device of claim 10, wherein the polarity corrector is configured to reverse a third polarity of a third symbol and a fourth polarity of a fourth symbol and the physical coding sublayer module is configured to initiate transmission of the third symbol and the fourth symbol to the another communication device.

14. The communication device of claim 10, wherein the physical coding sublayer module receives, during a full-duplex link initialization stage, a third symbol and a fourth symbol from the another communication device and the polarity corrector is configured to reverse a third polarity of the third symbol and a fourth polarity of the fourth symbol.

15. The communication device of claim 10, wherein the communication device further comprises a medium independent interface that is coupled to a single twisted pair of wires, the first training symbols are received over a first wire of the single twisted pair of wires, and the second training symbols are received over a second wire of the single twisted pair of wires.

16. The communication device of claim 10, wherein the symbol boundary delineates individual symbols of the first and second training symbols.

17. A computer program product comprising instructions stored in a non-transitory computer-readable storage medium, the instructions comprising:

instructions to receive first training symbols via a first channel and second training symbols via a second channel during a half-duplex link initialization stage;

instructions to determine, during the half-duplex link initialization stage, whether a first polarity associated with the first channel is reversed based at least on whether a descrambler can be locked using at least the first symbols or using the first symbols with the first polarity reversed;

instructions to change, during the half-duplex link initialization stage, a symbol boundary associated with the first training symbols and the second training symbols when the descrambler cannot be locked using at least the first symbols or using the first symbols with the first polarity reversed;

instructions to determine, during the half-duplex link initialization stage, whether the first polarity associated with the first channel is reversed based at least on whether the descrambler can be locked using at least the first symbols with the changed symbol boundary or using the first symbols with the changed symbol boundary and the first polarity reversed; and

instructions to reverse the first polarity of the first symbols subsequently received, and transmitted, over the first channel and a second polarity of second symbols subsequently received, and transmitted, over the second channel when the first polarity associated with the first channel is reversed.

18. The computer program product of claim 17, wherein the first channel comprises a first wire of a twisted pair of wires and the second channel comprises a second wire of the twisted pair of wires.

19. The computer program product of claim 17, wherein the symbol boundary delineates individual symbols.

20. The computer program product of claim 17, wherein a handshaking signal encoded by the first and second symbols is set to false, and the instructions further comprise:

instructions to determine, during the half-duplex link initialization stage, whether the first polarity associated with the first channel is reversed based at least on the handshaking signal being set to false and whether the descrambler can be locked using at least the first symbols.