Method and apparatus for automatic detection and healing of signal pair crossover on a high performance serial bus

• US 7,401,173 B1
• Filed: 05/27/2005
• Issued: 07/15/2008
• Est. Priority Date: 04/21/2000
• Status: Expired due to Term

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Whitby-Strevens, Colin
• Primary Examiner(s): Myers; Paul R
• Application Number:
  US11/139,815
• Time in Patent Office: 1,145 Days
• Field of Search: 710/305, 710/316, 710/10, 710/100, 710/104, 710/105, 710/107, 710/119, 710/124, 710/5, 710/8, 710/40, 709/220, 370/228
• US Class Current: 710/305
• CPC Class Codes: G06F 13/4068 Electrical coupling
• CPC Class Codes: G06F 13/4295 using an embedded synchronisation

Abstract

An automatic crossover and healing process is disclosed for the P1394b standard. In particular, a crossover process is disclosed which comprises coupling the transmitting logic of a PHY to TPA, and coupling the receive logic of a PHY to TPB.

Claims

1. A computer readable medium containing instructions, which, when executed by a computer, detects and heals a crossover in a data communications system having a P1394b-compliant bus and a PHY which wishes to join the bus, by:

determining whether the PHY has received a tone;

if the PHY has not received a tone, then examining a random Boolean value; and

if the value of said random Boolean value is true, then implementing a crossover process.

2. The computer readable medium of claim 1, wherein said crossover process comprises coupling the transmitting logic of said PHY to TPA, and coupling the receive logic of said PHY to TPB.

3. A computer readable medium containing instructions, which, when executed by a computer, detects and heals a crossover in a data communications system having a P1394b-compliant bus and a PHY which wishes to join the bus, by:

determining whether the PHY has received a tone;

if the PHY has not received a tone, then examining a random Boolean value;

if the value of said random Boolean value is true, determining, by said PHY, whether said PHY is sending a tone;

if said PHY is sending a tone, then waiting a predetermined period of time further determining by said PHY if said PHY has received a tone; and

if said PHY has not received a tone, then implementing, by said PHY, a crossover process.

4. The computer readable medium of claim 3, wherein said crossover process comprises coupling the transmitting logic of said PHY to TPA, and coupling the receive logic of said PHY to TPB.

5. Computerized apparatus, comprising:

a processor;

a signal interface in data communication with said processor; and

an interface controller adapted to control at least one aspect of the operation of said interface;

wherein said data apparatus is adapted to hot-connect to a bus operating according to a serialized protocol by;

detecting, via said signal interface, whether a first signal is present on the bus;

if said first signal is present on the bus, acknowledging said first signal via said first interface and negotiating a connection with an entity issuing said first signal;

or

if said first signal is not present on said bus, invoking a discontinuity correction mechanism to attempt to acquire said first signal.

6. The apparatus of claim 5, wherein said serialized protocol and said interface are capable of transmitting data at speeds of at least 200 Mbits/sec.

7. The apparatus of claim 6, wherein said apparatus is further adapted to:

determine whether said signal interface is generating a second signal before implementing said correction function; and

subsequently implement said correction mechanism only when said signal interface is not generating said second signal.

8. The apparatus of claim 6, wherein said interface further comprises correction logic, said logic adapted to couple transmission apparatus of said signal interface to at least one first signal pathway, and couple the receive apparatus of said interface to at least one second signal pathway.

9. The apparatus of claim 8, wherein said correction logic comprises a CMOS integrated circuit.

10. The apparatus of claim 5, wherein said interface comprises both transmit and receive signal pathways, said interface being capable of transmitting or receiving, respectively, signals over said transmit and receive pathways simultaneously.

11. A computer readable medium containing instructions which, when performed by a computer, automatically sense and correct a discontinuity condition associated with a signal interface joining a data communications system, said system utilizing a serialized bus protocol, said sensing and correcting being performed according to the method comprising:

determining that the signal interface has failed to receive a first signal;

examining the state of a variable; and

if said state meets a first criterion, implementing a discontinuity correction function;

wherein said state comprises one of a plurality of values of said variable, said one of said plurality of values being determined by an algorithm, said algorithm being utilized for resolving contention between two or more nodes of a network using said bus protocol.

12. A computer readable medium containing instructions which, when performed by a computer, automatically sense and correct a discontinuity condition associated with a signal interface joining a data communications system, said system utilizing a serialized bus protocol, said sensing and correcting being performed according to the method comprising:

determining that the signal interface has failed to receive a first signal;

examining the state of a randomized variable; and

if said state meets a first criterion, implementing a discontinuity correction function;

wherein said sensing and correcting is implemented as part of said signal interface joining said system after said system has been powered-up.

13. In a data communications apparatus utilizing a serialized bus protocol, a method for automatically sensing and correcting a discontinuity condition associated with a signal interface attempting to communicate with said apparatus, said method comprising:

determining that the signal interface has failed to receive a first signal;

substantially in response to said determining, examining the state of a random logic variable; and

if said state meets a first criterion, implementing a discontinuity correction function in order to correct said discontinuity condition and permit signal communication between said signal interface and at least a second signal interface associated with said apparatus.

14. In a data system comprising a bus operating according to a serialized protocol, a method for adding a signal interface to the bus, the method comprising:

placing said signal interface in signal communication with said bus;

detecting, via said signal interface whether a first signal is present on the bus;

if said first signal is present on the bus, acknowledging said first signal via said first interface;

or

if said first signal is not present on said bus, invoking a discontinuity correction function to attempt to acquire said first signal;

wherein said function comprises;

evaluating the state of at least one variable, said state comprising one of a plurality of values of said variable, said one of said plurality of values being determined by an algorithm adapted to generate random ones of said values; and

if said state meets a first criterion, correcting the inversion of two physical signal paths associated with said signal interface by swapping two signal paths within said interface.

15. A computer readable medium containing instructions which, when performed by a computer, automatically sense and correct a discontinuity condition associated with a signal interface joining a data communications system, said system utilizing a serialized bus protocol, said sensing and correcting being performed according to the method comprising:

determining that the signal interface has failed to receive a first signal;

examining the state of a random variable; and

if said state meets a first criterion, implementing a discontinuity correction function.

16. The computer readable medium of claim 15, wherein said discontinuity correction function comprises coupling the transmission logic of said signal interface to at least one first signal pathway, and coupling the receive logical of said interface to at least one second signal pathway.

17. The computer readable medium of claim 15, wherein said sensing and correcting is implemented as part of said signal interface joining said system after said system has been powered-up.

18. The computer readable medium of claim 17, wherein said random variable comprises a Boolean variable.

19. The computer readable medium of claim 15, wherein said state of said variable being determined by an algorithm.

20. The computer readable medium of claim 19, wherein said algorithm is utilized for another purpose within said serialized bus protocol.

21. The computer readable medium of claim 20, wherein said another purpose comprises resolving contention between two or more nodes of a network using said bus protocol.

22. The computer readable medium of claim 15, wherein said first signal comprises a tone generated by a second signal interface in data communication with said system.

23. The computer readable medium of claim 15, wherein said method further comprises determining whether said signal interface is generating a second signal before implementing said correction function.

24. In a data communications apparatus utilizing a serialized bus protocol, a method for automatically sensing and correcting a discontinuity condition associated with a signal interface attempting to communicate with said apparatus, said method comprising:

determining that the signal interface has failed to receive a first signal;

pausing for a first period of time, wherein said first period of time is determined at least in part by a random function; and

implementing a discontinuity correction function in order to correct said discontinuity condition and permit signal communication between said signal interface and at least a second signal interface associated with said apparatus.

25. The method of claim 24, wherein said discontinuity condition comprises the inversion of two physical signal paths associated with said signal interface, and said correction comprises swapping the two signal paths within said interface.

26. The method of claim 25, wherein said sensing and correcting is implemented as part of said signal interface joining said system after said system has been powered-up.

27. The method of claim 24, wherein said discontinuity correction function comprises coupling the transmission logic of said signal interface to at least one first signal pathway, and coupling the receive logic of said interface to at least one second signal pathway.

28. The method of claim 24, wherein pausing for a first period of time comprises repeatedly examining the state of a variable until a certain condition is satisfied.

29. The method of claim 28, wherein said state comprises one of a plurality of values of said variable, said one of said plurality of values being determined by an algorithm.

30. The method of claim 29, wherein said algorithm is utilized for another purpose within said serialized bus protocol.

31. The method of claim 30, wherein said another purpose comprises resolving contention between two or more nodes of a network using said bus protocol.

32. The method of claim 24, wherein said first signal comprises a tone generated by a second signal interface in data communication with said apparatus.

33. The method of claim 24, wherein said method further comprises:

determining whether said signal interface is generating a second signal before implementing said correction function; and

subsequently implementing said correction function only when said signal interface is not generating said second signal.

34. The method of claim 24, wherein said method further comprises pausing for a second period of time before implementing said correction function, wherein said second period of time is non-random.

35. In a data system comprising a bus operating according to a serialized protocol, a method for adding a signal interface to the bus, the method comprising:

placing said signal interface in signal communication with said bus;

detecting, via said signal interface whether a first signal is present on the bus;

if said first signal is present on the bus, acknowledging said first signal via said interface;

or

if said first signal is not present on said bus, invoking a local discontinuity correction function to attempt to acquire said first signal;

wherein the local discontinuity correction function is adapted to break synchronization with a remote discontinuity correction function by a process other than clock drift.

36. The method of claim 35, wherein said discontinuity correction function is adapted to correct the inversion of two physical signal paths associated with said signal interface by swapping two signal paths within said interface.

37. The method of claim 35, wherein said method is implemented as part of said signal interface being added to said system after said system has been powered-up.

38. The method of claim 35, wherein said discontinuity correction function is adapted to couple the transmission logic of said signal interface to at least one first signal pathway, and couple the receive logic of said interface to at least one second signal pathway.

39. The method of claim 35, wherein if said state meets a first criterion, correcting the inversion of two physical signal paths associated with said signal interface by swapping two signal paths within said interface.

40. The method of claim 39, wherein said state comprises one of a plurality of values of said variable, said one of said plurality of values being determined by an algorithm adapted to generate random ones of said values.

41. The method of claim 40, wherein said algorithm is utilized for another purpose within said serialized protocol.

42. The method of claim 35, wherein said first signal comprises a tone generated by a second signal interface in data communication with said bus.

43. In a data communications apparatus utilizing a serialized bus protocol, a method for automatically sensing and correcting a discontinuity condition associated with a signal interface attempting to communicate with said apparatus, said method comprising:

determining that the signal interface has failed to receive a first signal;

substantially in response to said determining, examining the output of a random function; and

if said output meets a first criterion, implementing a discontinuity correction function in order to correct said discontinuity condition and permit signal communication between said signal interface and at least a second signal interface associated with said apparatus.

44. In a data communications apparatus utilizing a serialized bus protocol, a method for automatically sensing and correcting a discontinuity condition associated with a signal interface attempting to communicate with said apparatus, said method comprising:

determining that the signal interface has not received a first signal;

substantially in response to said determining, examining the output of a random function; and

if said output meets a first criterion, implementing a discontinuity correction function in order to correct said discontinuity condition and permit signal communication over said signal interface.