METHOD AND DEVICE FOR SERIALLY TRANSFERRING DATA, HAVING SWITCHABLE DATA ENCODING

• US 20140298133A1
• Filed: 04/19/2012
• Published: 10/02/2014
• Est. Priority Date: 04/20/2011
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Hartwich, Florian, Lindenkreuz, Thomas
• Granted Patent: US 9,300,323 B2
• Time in Patent Office: Days
• US Class Current: 714/758
• CPC Class Codes: G06F 13/4295 using an embedded synchronisation
• CPC Class Codes: H03M 13/09 Error detection only, e.g. using cyclic redundancy check [CRC] codes or single parity bit
• CPC Class Codes: H04L 12/417 with deterministic access, e.g. token passing
• CPC Class Codes: H04L 2012/40215 Controller Area Network CAN

Abstract

A method and an apparatus for data transfer in a network having at least two data processing units that exchange messages via the network are described, the exchanged messages having a logical structure in accordance with the CAN specification ISO 11898-1, coding of the bits for at least one first predefinable region within the exchanged messages being accomplished according to the method in accordance with the CAN standard ISO-11898-1, and such that when a switchover condition exists, coding of the bits for at least one second predefinable region within the exchanged messages is accomplished according to a method departing from the CAN standard ISO 11898-1.

Claims

1-28. -28. (canceled)

29. A method for data transfer in a network having at least two data processing units that exchange messages via the network, the exchanged messages having a logical structure in accordance with CAN standard ISO 11898-1, the method comprising:

coding bits for at least one first predefinable region within the exchanged messages according to a method in accordance with the CAN standard ISO-11898-1, and

when a switchover condition exists, coding bits for at least one second predefinable region within the exchanged messages according to a method departing from the CAN standard ISO 11898-1.

30. The method according to claim 29, wherein the coding for the second predefinable region is selected such that an elevated data transfer rate, elevated immunity to external interference and/or less emission of electromagnetic waves is achieved.

31. The method according to claim 29, wherein the coding for the second predefinable region includes an NRZ coding that has a smaller voltage swing as compared with the CAN standard and in which a recessive level is weakly driven.

32. The method according to claim 29, wherein the coding for the second predefinable region includes an NRZI coding, an occurrence of a signal edge being interpreted as dominant and an absence of an edge being interpreted as recessive.

33. The method according to claim 29, wherein the coding for the second predefinable region includes a frequency modulation or frequency shift, a first frequency or group of frequencies, or a first frequency range, being interpreted as dominant, and a second frequency or group of frequencies, or a second frequency range, being interpreted as recessive.

34. The method according to claim 33, wherein a third frequency or group of frequencies, or a third frequency range, is utilized in the second predefinable region to signal a detected error in the data transfer.

35. The method according to claim 29, the coding for the second predefinable region includes an amplitude modulation or amplitude shift, a first amplitude or a first amplitude range being interpreted as dominant, and a second amplitude or a second amplitude range being interpreted as recessive.

36. The method according to claim 35, wherein a third amplitude or a third amplitude range is utilized in the second region to signal a detected error in the data transfer.

37. The method according to claim 29, wherein in the second predefinable region, besides the transfer of bits having alternative coding, data are additionally also transferred in accordance with the CAN standard ISO 11898-1.

38. The method according to claim 29, wherein when the switchover condition exists, besides a change in the coding of the bits, a change in a bus clock rate also takes place in a third predefinable region, the third predefinable region being encompassed by the second predefinable region or coinciding with the second predefinable region.

39. The method according to claim 38, wherein the change in the bus clock rate is realized by utilizing at least two different scaling factors for setting a bus time unit relative to a smallest time unit or to an oscillator clock rate in a course of operation.

40. The method according to claim 38, wherein in the second or third predefinable region, an electrical resistance between bus leads is adapted to a transfer method used in the respective predefinable region.

41. The method according to claim 29, wherein the second predefinable region of bus subscribers ends immediately after detection of a reason for starting an error frame or immediately after a bit stipulated for switching back is reached, and coding of the bits in the bus subscribers is again accomplished according to the method of the first predefinable region.

42. The method according to claim 39, wherein the third predefinable region of bus subscribers ends immediately after detection of a reason for starting an error frame or immediately after a bit stipulated for switching back is reached, and the bus clock rate in the bus subscribers is set back to a value of the first predefinable region.

43. The method according to claim 29, wherein bus access is assigned by arbitration in accordance with ISO 11898-1, the second predefinable region in which a discrepant coding of the bits can be accomplished beginning within the message at an earliest with a first bit of a data length code, and ending at a latest with a bit of a CRC delimiter.

44. The method according to claim 29, wherein an existence of a switchover condition is signaled to the data processing units exchanging the messages by an identifier located within the first predefinable region.

45. The method according to claim 44, wherein the identifier is implemented by a reserved bit within a control field or an arbitration field of the message.

46. The method according to claim 29, wherein bus access is assigned by way of a time-controlled method in accordance with ISO 11898-4, and the second predefinable region in which a discrepant coding of the bits can be accomplished begins for predefinable messages within those messages at an earliest with a start of frame bit, and ends at a latest with a bit of a CRC delimiter.

47. The method according to claim 46, wherein an existence of a switchover condition for the predefinable messages is stipulated in a context of configuration of the time-controlled bus communication.

48. The method according to claim 46, wherein an existence of a switchover condition for the predefinable messages is signaled to the data processing units exchanging messages by an identifier located in a previously transmitted reference report.

49. The method according to claim 29, wherein a transition to the second predefinable region in bus subscribers is carried out immediately after detection of an identifier stipulated for the switchover or of a bit stipulated for the switchover, and the coding of the bits is changed.

50. The method according to claim 29, wherein a transition to the third predefinable region in bus subscribers is carried out immediately after detection of an identifier stipulated for the switchover or of a bit stipulated for the switchover, and a bus clock rate is changed.

51. The method according to claim 29, wherein a communication protocol is modified such that transmitting bus subscribers, at least when the switchover condition exists, accept an acknowledgement of correct reception of a message by one or more receivers that is one bit too late with respect to CAN standard ISO 11989-1, and/or an acknowledge slot that is a maximum of two bits long, and do not treat it as an error.

52. An apparatus for data transfer in a network having at least two participating data processing units and a connection for the transfer of messages,

wherein the data transfer is accomplished according to a method comprising:

coding bits for at least one first predefinable region within exchanged messages according to a method in accordance with CAN standard ISO-11898-1, and

when a switchover condition exists, coding bits for at least one second predefinable region within the exchanged messages according to a method departing from the CAN standard ISO 11898-1.

53. The apparatus according to claim 52, further comprising:

means for activating a bus terminal unit or a terminating unit, the bus terminal unit or the terminating unit being adapted, by way of the activation, to the data transfer method being used.

54. The apparatus according to claim 52, further comprising:

terminals for connection to multiple bus terminal units provided at least in a receiving branch, the multiple bus terminal units being set up to execute the various data transfer methods that are used.

55. A bus terminal unit for data transfer in a network having at least two participating data processing units and a connection for the transfer of messages,

wherein the data transfer is accomplished according to a method comprising:

coding bits for at least one first predefinable region within exchanged messages according to a method in accordance with CAN standard ISO-11898-1, and

when a switchover condition exists, coding bits for at least one second predefinable region within the exchanged messages according to a method departing from the CAN standard ISO 11898-1.

56. The bus terminal unit according to claim 55, further comprising:

means for adapting the bus terminal unit to the data transfer method being used, the means encompassing at least one switchable termination unit or one switchable resistor.