METHOD AND DEVICE FOR SERIAL DATA TRANSMISSION WHICH IS ADAPTED TO MEMORY SIZES

• US 20140156887A1
• Filed: 04/26/2012
• Published: 06/05/2014
• Est. Priority Date: 04/26/2011
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Hartwich, Florian
• Granted Patent: US 9,825,852 B2
• Time in Patent Office: Days
• US Class Current: 710/105
• CPC Class Codes: G06F 13/4282 on a serial bus, e.g. I2C bus, SPI bus on daisy chain buses G06F13/4247
• CPC Class Codes: G06F 5/065 Partitioned buffers, e.g. allowing multiple independent queues, bidirectional FIFO's
• CPC Class Codes: H04L 12/40013 Details regarding a bus controller
• CPC Class Codes: H04L 12/4135 using bit-wise arbitration
• CPC Class Codes: H04L 2012/40215 Controller Area Network CAN
• CPC Class Codes: H04L 45/74 Address processing for routing

Abstract

A method is described for serial data transmission in a bus system having at least two participating data processing units, the data processing units exchanging messages via the bus, the sent messages having a logical structure in accordance with CAN standard ISO 11898-1. When a first changeover condition is present, then, deviating from CAN, the data field of the messages can include more than eight bytes, the values of the data length code being interpreted, given the presence of the first changeover condition to determine the size of the data field. For forwarding data between the data field and the application software, at least one buffer memory is provided, and, if the size of the data field differs from the size of the buffer memory used, the forwarded quantity of data is adapted at least corresponding to the difference in size between the data field and the buffer memory.

Claims

1-28. -28. (canceled)

29. A method for serial data transmission in a bus system having at least two participating data processing units that exchange messages via the bus, sent messages having a logical structure in accordance with CAN standard ISO 11898-1, the logical structure including a start-of-frame bit, an arbitration field, a control field, a data field, a CRC field, an acknowledge field, and an end-of-frame sequence, the control field including a data length code that contains an item of information about the length of the data field, wherein given the presence of a first changeover condition, deviating from CAN standard ISO 11898-1, the data field of the messages can include more than eight bytes, at least one buffer memory being provided for forwarding of data between the data field and application software, the method comprising:

interpreting values of the data length code, at least partly in a manner deviating from CAN standard ISO 11898-1, to determine a size of the data field, when the first changeover condition is present; and

if the size of the data field differs from the size of the buffer memory, adapting the data to be forwarded to the application software in a manner at least corresponding to the difference in size between the data field and the buffer memory.

30. The method as recited in claim 29, further comprising:

if the size of the data field is greater than the size of the buffer memory used, selecting from the data field of a message received via the bus a quantity of data corresponding to the size of the buffer memory according to a specified selection method, and forwarding the quantity of data to the buffer memory.

31. The method as recited in claim 29, further comprising:

entering contents of the buffer memory into at least one region of the data field of a message to be sent via the bus, and filling remaining regions of the data field according to a specified method if the size of the data field is greater than the size of the buffer memory used.

32. The method as recited in claim 29, wherein if the size of the data field of a message received via the bus is more than eight bytes, eight specified bytes of the data field are given to the application software via the at least one buffer memory.

33. The method as recited in claim 32, wherein if the size of the data field of a message to be sent via the bus is more than eight bytes, remaining bits of the data field are filled with specified values.

34. The method as recited in claim 33, wherein the bits in filled regions of the data field of a message to be sent via the bus are filled in such a way that, in accordance with the rules of CAN standard ISO 11898-1, no stuff bits need be inserted in these regions.

35. The method as recited in claim 34, wherein as a function of the value of the first changeover condition, each of possible value combinations of the four bits of the data length code is assigned to one of the allowable sizes of the data field.

39. The method as recited in claim 29, wherein as a function of the value of a changeover condition, the CRC field of messages can have at least two different numbers of bits, at least one of the valid numbers of bits in the CRC field being a number of bits deviating from CAN standard ISO 11898-1, a generator polynomial deviating from CAN standard ISO 11898-1 being used to determine contents of a CRC field having a deviating number of bits.

50. A device for serial data transmission in a bus system having at least two participating data processing units that exchange messages via the bus, the sent messages having a logical structure in accordance with CAN standard ISO 11898-1, the logical structure including a start-of-frame bit, an arbitration field, a control field, a data field, a CRC field, an acknowledge field, and an end-of-frame sequence, the control field including a data length code that contains an item of information about the length of the data field, wherein given the presence of a first changeover condition, deviating from CAN standard ISO 11898-1 the data field of the messages can include more than eight bytes, wherein the device is configured to interpret values of the data length code, when the first changeover condition is present, at least partly in a manner deviating from CAN standard ISO 11898-1 to determine the size of the data field, wherein the device includes at least one buffer memory for forwarding of data between the data field and application software, and wherein the device is configured to adapt a quantity of data to be forwarded to the application software in a manner at least corresponding to a difference in size between the data field and the buffer memory used if the size of the data field differs from the size of the buffer memory used.

51. The device as recited in claim 50, wherein the device is configured to select from the data field of a message received via the bus, a quantity corresponding to the size of the memory buffer according to a detection method, and to forward the quantity of data to the buffer memory of the size of the data field is greater than the size of the buffer memory.

52. The device as recited in claim 51, wherein the device further includes at least one protocol control unit to adapt the quantity of data forwarded between the data field and the buffer memory in a manner corresponding to the difference in size between the data field and the buffer memory.

53. The device as recited in claim 52, wherein the device includes at least one additional or expanded status register whose content identifies at least one of:

i) a type, ii) a success, and iii) a result, of the respectively used data transmission method.

54. The device as recited in claim 53, wherein the device includes at least one of:

i) an additional message memory, ii) an expanded message memory, and iii) a buffer memory, in which at least one additional message bit identifies the method of data transmission that is used for the respective message.

55. A method for serial data transmission in a bus system of a motor vehicle having at least two control devices that exchange messages, via the bus, sent messages having a logical structure in accordance with CAN standard ISO 11898-1, the logical structure including a start-of-frame bit, an arbitration field, a control field, a data field, a CRC field, an acknowledge field, and an end-of-frame sequence, the control field including a data length code that contains an item of information about the length of the data field, wherein given the presence of a first changeover condition, deviating from CAN standard ISO 11898-1, the data field of the messages can include more than eight bytes, at least one buffer memory being provided for forwarding of data between the data field and application software, the method comprising:

interpreting values of the data length code, at least partly in a manner deviating from CAN standard ISO 11898-1, to determine a size of the data field, when the first changeover condition is present; and

if the size of the data field differs from the size of the buffer memory, adapting the data to be forwarded to the application software in a manner at least corresponding to the difference in size between the data field and the buffer memory.

56. A method for serial data transmission in a bus system of an industrial installation having at least two control devices that exchange messages, via the bus, sent messages having a logical structure in accordance with CAN standard ISO 11898-1, the logical structure including a start-of-frame bit, an arbitration field, a control field, a data field, a CRC field, an acknowledge field, and an end-of-frame sequence, the control field including a data length code that contains an item of information about the length of the data field, wherein given the presence of a first changeover condition, deviating from CAN standard ISO 11898-1, the data field of the messages can include more than eight bytes, at least one buffer memory being provided for forwarding of data between the data field and application software, the method comprising:

interpreting values of the data length code, at least partly in a manner deviating from CAN standard ISO 11898-1, to determine a size of the data field, when the first changeover condition is present; and

if the size of the data field differs from the size of the buffer memory, adapting the data to be forwarded to the application software in a manner at least corresponding to the difference in size between the data field and the buffer memory.

57. A method for serial data transmission in a bus system of a motor vehicle, the bus system including a control device of the motor vehicle and a programming unit connected to the bus system for programming during manufacturing or maintenance of the motor vehicle, the control device and the programming unit exchanging messages via the bus, sent messages having a logical structure in accordance with CAN standard ISO 11898-1, the logical structure including a start-of-frame bit, an arbitration field, a control field, a data field, a CRC field, an acknowledge field, and an end-of-frame sequence, the control field including a data length code that contains an item of information about the length of the data field, wherein given the presence of a first changeover condition, deviating from CAN standard ISO 11898-1, the data field of the messages can include more than eight bytes, at least one buffer memory being provided for forwarding of data between the data field and application software, the method comprising:

interpreting values of the data length code, at least partly in a manner deviating from CAN standard ISO 11898-1, to determine a size of the data field, when the first changeover condition is present; and

if the size of the data field differs from the size of the buffer memory, adapting the data to be forwarded to the application software in a manner at least corresponding to the difference in size between the data field and the buffer memory.

58. A method for serial data transmission in a bus system of an industrial installation, the bus system including a control device of the industrial installation and a programming unit connected to the bus system for programming during manufacturing or maintenance of the industrial installation, the control device and the programming unit exchanging messages via the bus, sent messages having a logical structure in accordance with CAN standard ISO 11898-1, the logical structure including a start-of-frame bit, an arbitration field, a control field, a data field, a CRC field, an acknowledge field, and an end-of-frame sequence, the control field including a data length code that contains an item of information about the length of the data field, wherein given the presence of a first changeover condition, deviating from CAN standard ISO 11898-1, the data field of the messages can include more than eight bytes, at least one buffer memory being provided for forwarding of data between the data field and application software, the method comprising:

interpreting values of the data length code, at least partly in a manner deviating from CAN standard ISO 11898-1, to determine a size of the data field, when the first changeover condition is present; and

if the size of the data field differs from the size of the buffer memory, adapting the data to be forwarded to the application software in a manner at least corresponding to the difference in size between the data field and the buffer memory.