JP4574377B2 - Data processing module and method for managing transmitted / received messages thereof - Google Patents

Description

  The present invention relates to a data processing module and a method for managing transmission / reception messages thereof.

  In recent years, multi-master communication protocols have attracted attention as communication protocols. In the multi-master protocol, when the bus is released, any of a plurality of communication nodes connected to the bus can transmit data on the bus, and the system is highly flexible. ing. As such a multi-master communication protocol, a multi-master CAN (Controller Area Network) described in Japanese Patent Application Laid-Open No. 61-195453 is used as a serial communication protocol between ECUs (electronic control units) in an automobile. , Hereinafter referred to as CAN) (standardized by ISO 11898 and ISO 11519 series) is known. Such a multi-master communication protocol has high system flexibility such that communication nodes can be easily increased / decreased. Therefore, the multi-master communication protocol is not limited to the above-described automobile field, but is a communication protocol in fields such as FA (Factory Automation), ships, and medical devices. As promising.

FIG. 12 is a diagram illustrating a schematic configuration of a CAN as a communication node. It is possible to connect CAN modules 11, 1n, 16 having a CAN transceiver 60 connected to a CAN bus (not shown) constituting a sub-network, and each CAN module 11, 1n, 16 is connected to the CPU I. It is possible to send and receive messages via the / F (interface) 40. Further, the CAN module 19 in FIG. 12 can only receive a message.
JP-A 61-195453

  In the CAN protocol, page 30, lower left column 5) -1.1.4 queue of messages to be transmitted, and page 35, lower left column 5) -3.6 The search process is shown below. As described above, prior to message transmission, a transmission search process is performed to determine a transmission candidate message from the buffer in which the transmission request bit is set. In addition, even when a message is received, page 30, lower left column 5) -1.1.5 queue of received messages and page 35, upper right column 5) -3 data exchange DPRAM as shown below A reception search process is performed to determine whether or not the identifier of the received message is stored in the message buffer (DPRAM as referred to in the same publication). When the received message identifier is stored in the message buffer, an interrupt request bit is set.

  FIG. 13 is a diagram showing a configuration of a message buffer provided in the CAN module, and FIG. 14 is a flowchart showing an operation after a reception interrupt is generated when a message is received. Conventionally, as shown in FIG. 14, after the occurrence of a reception interrupt (step S101), the CPU performs read access to all reception buffers (step S102), and a DN bit (data) indicating whether or not each buffer has been updated. The status of the (update bit) is confirmed and the reception buffer is specified (step S103). The transmission process is the same, and all buffers are searched, the state of the TRQ bit (transmission request bit) is confirmed, and the transmitted buffer is specified.

  (A) in the upper part of FIG. 15 is a timing chart in the case where the CPU can follow the reception completion interrupt signal after completion of reception writing (Rx) by CAN, and (B) in the lower part of FIG. 15 is reception by CAN. It is a timing chart of the state which became impossible for CPU to follow the reception completion interruption signal after completion | finish of writing (Rx). As shown in FIG. 5A, the conventional method needs to read all the buffers each time, so that it takes time to specify the buffers and the load on the CPU is high. Further, as shown in FIG. 5B, when reception precedes and buffer specification is delayed, DN bit = 1 is detected in a plurality of buffers, and the order of transmission / reception is lost from the CPU. There was a problem.

  In addition, the CAN performs a transmission / reception search in advance and then designates the position of the message buffer to read / write the message. The order in which transmission / reception is performed can be specified from the buffer position on the message buffer. There is a circumstance that cannot be done. The above-mentioned problem also occurs when grasping the order of messages to be transmitted. If the configuration includes a plurality of transmission buffers or reception buffers and performs direct read / write by specifying a position. It can be said that this is not a problem.

According to the first aspect of the present invention, according to the first aspect of the present invention, one message can be stored in the data processing module connected to the multi-master network represented by the above-mentioned CAN. Provided is a transmission / reception message management method that includes a history buffer capable of storing history information indicating a buffer position of an update message on a message buffer having a plurality of buffers for a predetermined number of times, and that can specify a message transmission / reception order. According to this method, first, when the message handling unit of the data processing module (CAN module) first updates an arbitrary buffer of an arbitrary message buffer, the position information of the updated buffer is obtained as follows: Store (record) at the next write position of the history buffer. In addition, the message handling unit sequentially updates an unread pointer indicating the position of history information unreferenced from the CPU in the history buffer in response to a read access from a CPU (Central Processing Unit). The latest write position and unread pointer in the history buffer can be referred to by the CPU, and the storage position of the latest message and the oldest unread message can be specified.

Further, according to the second aspect of the present invention, there is provided a data processing module (CAN module) having a configuration and a circuit configuration suitable for implementing the above-described transmission / reception message management method. In other words, this data processing module (CAN module) includes a plurality of buffers, and includes a message buffer having a plurality of buffers capable of storing a message to be transmitted and a received message, and at least a buffer in which a received message is stored. A history buffer that holds and manages the address and the order in which the received messages are received, and a message handling unit that manages messages on the message buffer.

  According to the present invention, it is possible to quickly specify a buffer to be processed, and it is possible to reduce the load on the CPU and the possibility of delay in specifying the buffer. In addition, even if there is a delay in specifying the buffer, the transmission / reception order can be traced by the history buffer, and processing omission can be eliminated.

  Next, the best mode for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram illustrating a schematic configuration of a CAN device 100 in which a CAN module (data processing module) according to the present embodiment, a CPU 51, a RAM 52, and a peripheral circuit 53 are configured in one chip. For example, the peripheral circuit 53 includes an I / O circuit, and is connected to various sensors and display devices provided outside the CAN device 100 and performs an interface between the outside and the inside. The CPU 51 receives data from the various sensors. Is taken out via I / O, and the RAM is used to execute a desired process to write to the message buffer, and the message written to the message buffer is taken out and the desired process is executed. A process of transmitting data to a display device connected to is performed.

  The CAN module includes a history buffer composed of a message handling unit 2, a message buffer 3, a CAN protocol transmission layer 4, a mask set 5, and a ring buffer 6 controlled to be written in a ring shape by a CAN write pointer described later. ing.

  FIG. 2 is a diagram showing a detailed configuration of the message handling unit 2 of the CAN module described above. Referring to FIG. 2, the message handling unit 2 is connected to the message buffer 3 and the ring buffer 6 in order to read out data from the message buffer 3 in order to realize a history information providing function in addition to a configuration necessary for transmitting and receiving messages. As a data protection circuit for preventing data from being destroyed, a CAN write pointer 21 and an oldest (unread) history information pointer 23 composed of flip-flop circuits are provided, and further dependent on the contents of each pointer. The latest history information pointer 22, the history invalid flag 24, and the overflow flag 25 are configured. In addition, the latest history information pointer 22, the oldest (unread) history information pointer 23, the history invalid flag 24, and the overflow flag 25 surrounded by a double line in the figure are kept visible to the CPU 51.

  When message writing is completed in a predetermined buffer of the message buffer 3, the message handling unit 2 records history information (message number of the buffer) in the ring buffer 6 based on the value of the CAN write pointer 21. The latest history information pointer 22 indicates the position immediately before the position indicated by the CAN write pointer 21, and stores the message number of the buffer that was most recently written (most recently). The oldest (unread) history information pointer 23 coincides with the CAN write pointer 21 in the initial state. However, the oldest (unread) history information pointer 23 always shifts to indicate the oldest unread history information in conjunction with the read access from the CPU 51. To go.

  The history invalid flag 24 indicates a state in which the resources of the ring buffer 6 are not used at all. For example, the history invalid flag 24 is set to the ON state level “1” when the CAN write pointer 21 = the oldest (unread) history information pointer 23, and the CAN write pointer 21 ≠ the oldest (unread) history information pointer 23. Is set to the off state level “0”. The overflow flag 25 indicates a state where the resources of the ring buffer 6 are used. For example, the overflow flag 25 is set to the on state level “1” when the CAN write pointer 21 coincides with the position immediately before the oldest (unread) history information pointer 23, and the off state level otherwise. Set to “0”.

  FIG. 3 is a diagram illustrating the configuration of the message buffer and the ring buffer. Referring to FIG. 3, the message buffer 3 has a predetermined number in the order of an identifier (ID) indicating message priority, a control field (control segment) for designating whether or not the message is a transmission request message, and a message body length, and a message body. (N) messages can be buffered.

  The ring buffer 6 is configured to store 24 reception history information (Reception History List) at addresses from RHL0 to RHL23. The ring buffer 6 has 8 transmission histories at addresses from THL0 to THL7. Information (Transmission History List) can be stored. For example, if message number # 1 is recorded in RHL0 of ring buffer 6, message number #m is recorded in RHL1, and message number # 3 is recorded in RHL2, the message number in message buffer 3 is indicated by the arrow in FIG. This means that messages are received in the order of # 1, message number #m, and message number # 3.

  The CAN protocol transmission layer 4 transmits / receives data to / from the CAN transceiver according to the CAN protocol. The mask set 5 is used when masking a predetermined part of the message (for example, a part of the ID). For example, assuming that the ID is binary 4-bit data, the message at address n in the message buffer at addresses 0 to 31 is used. When ID 1100 is assigned to the buffer 3, 0000, 0100, and 1000 other than 1100 are stored in the address message buffer by masking the upper 2 bits.

  FIG. 4 is a diagram showing an operation when a reception interrupt occurs in the CAN module according to the present embodiment. Referring to FIG. 4, when writing to the message buffer is performed by the CAN module and a reception interrupt signal is transmitted to the CPU (step S001), the CPU 51 displays the position indicated by the oldest (unread) history information pointer 23. The ring buffer information indicated by the oldest (unread) history information pointer is read (step S002). As described above, the ring buffer 6 can record history information for a predetermined number of times (23 in this embodiment), and the content of the oldest (unread) history information pointer is linked to the read access of the CPU 51, and the CPU The oldest (unread) history information pointer 23 can identify the oldest buffer that has not been referred to in the message buffer 3 (step S003).

  FIG. 5 is a timing chart showing the operation when a message is received according to this embodiment. (A) Even when the CPU can follow the receiving operation of the CAN module, it is not necessary to read many DN bits, so the CPU processing time can be greatly shortened and the load can be reduced. It has become. Also, if the lower part (B) of the figure is in a state where the CPU cannot follow the reception operation of the CAN module, as described with reference to FIG. In the invention, information arranged in the order of arrival of messages can be given to the CPU. Therefore, it is possible to cause the CPU to steadily process the messages stored in the message buffer first, and to process the last received message first using the latest history information.

  In this embodiment, as shown in FIG. 6, the ring buffer 61 for reception, the ring buffer 62 for transmission, the CAN read pointer, the latest history information pointer, the oldest (unread) history information pointer, the history Configuration in which the CPU can provide the CPU with the order of messages transmitted by the CAN module by providing a pointer corresponding to the invalid flag and the overflow flag (in the case of transmission, the CAN write pointer becomes a CAN read pointer) and a flag. Can also be adopted.

[Example]

  Subsequently, in order to more specifically describe the above-described operation and effect of the present invention, an operation example having the above-described configuration will be described in order. FIG. 7 is a diagram showing an initial state, that is, a state in which history information is not stored in the ring buffer 6. RHL0 to RHL23 of the ring buffer 6 are indefinite, and the CAN write pointer 21 and the oldest (unread) history information pointer 23 are in a state pointing to the initial position RHL0. Further, the latest history information pointer 22 points to a position RHL 23 that is one return from the CAN write pointer 21. In this state, since the CAN write pointer 21 and the oldest (unread) history information pointer 23 match, the history invalid flag 24 is set.

  FIG. 8 is a diagram showing a state where the CAN module receives two messages after the initial state of FIG. 7 and stores the first message in buffer # 31 and the next message in buffer # 1. Message numbers msg # 31 and msg # 1 indicating the position of the buffer storing the message are recorded in RHL0 and RHL1, respectively, by the message handling unit 2. The CAN write pointer 21 points to the RHL to be written next, and the oldest (unread) history information pointer 23 remains pointing to the initial position RHL0 at the present stage when the CPU does not perform read access. Further, the latest history information pointer 22 points to a position RHL1 that is one return from the CAN write pointer 21. In this state, since the CAN write pointer 21 and the oldest (unread) history information pointer 23 do not match, the history invalid flag 24 is changed to the level “0”. Therefore, the CPU confirms that the history information is valid by the history invalid flag 24, the message number msg # 31 from the oldest (unread) history information pointer 23, and the message number msg from the latest history information pointer 22. It is possible to confirm # 1.

  FIG. 9 is a diagram illustrating a state where the CPU reads one message from a state where the CAN module of FIG. 8 has received two messages. As a result of the CPU read access, the oldest (unread) history information pointer 23 is moved from the initial position RHL0 to RHL1 by one. On the other hand, since the new history information is not written, the CAN write pointer 21 and the latest history information pointer 22 are not moved. Also, the history invalid flag 24 and the overflow flag 25 remain at level “0”. In this state, the CPU confirms that the history information is valid by the history invalid flag 24, and can confirm the message number msg # 1 from the oldest (unread) history information pointer 23 and the latest history information pointer 22. It is possible.

  FIG. 10 is a diagram showing a state immediately after the ring buffer 6 has run out as a result of many messages received by the CAN module preceding the read access of the CPU. In the figure, since the CAN write pointer 21 points to RHL8, the CAN module indicates a state immediately after the message number msg # 9 is written in RHL7. The oldest (unread) history information pointer 23 points to the RHL 9, and the history information from the RHL 9 to 23 and the RHL 0 to 7 is not yet read (in contrast to the oldest (unread) history information pointer 23. , The CAN write pointer 21 is preceded by about one round). The history invalid flag 24 remains at level “0”, and the CPU confirms that the history information is valid, and from the oldest (unread) history information pointer 23, the message number msg # 5, the latest history information pointer 22 Thus, the message number msg # 9 can be confirmed. In this state, the overflow flag 25 is set because the CAN write pointer 21 (= RHL8) and the position returned from the oldest (unread) history information pointer 23 (= (RHL9-1) = RHL8) match. It has been.

  FIG. 11 is a diagram showing a state in which a new message is received from the state where the overflow of FIG. 10 is established and stored in the message buffer. When the overflow flag 25 is at the level “1”, the CAN write pointer 21 holds the current value (RHL8), and the specific control is started to overwrite the history information at a position returned from the current position of the CAN write pointer 21. Is done. For example, in FIG. 11, the CAN write pointer 21 remains pointing to RHL8, but is decremented and msg # 27 is overwritten in RHL7. Such specific control is continued until the overflow flag is cleared. By performing such specific control, the value of the oldest (unread) history information pointer 23 is protected, and the state where the latest history information is always stored at the position specified by the latest history information pointer 22 is maintained. The

  As described above, since the contents of the ring buffer 6 are updated, the CPU immediately specifies a buffer in which a message that has not been referenced and is received first or a message that has been received first is stored. Is possible.

  The embodiment and examples of the present invention have been described above. However, as is clear from the principle, the technical scope of the present invention is not limited to the above-described embodiment, and reference is made to history information. Needless to say, various modifications and substitutions can be made without departing from the gist of the present invention, which allows the message to be processed to be determined immediately.

  For example, in the above-described embodiments and examples, an example of a pointer that can be read from the CPU has been described. However, an additional pointer may be provided so that it can be referred to. Also, the size of the ring buffer (the number of history information that can be stored) is not particularly limited, and can be changed according to the processing capacity of the CPU and the size of the message buffer.

  In the above-described embodiments and examples, the relationship between the CAN write pointer 21 and the oldest (unread) history information pointer 23 is determined in order to easily distinguish between a state where there is no history information (initial state) and an overflow state. Although the criteria (A = B and A = B-1) are distinguished from each other, a substantial overflow state may be determined by saving the immediately preceding state.

  In the above-described embodiments and examples, the ring buffer is used and specific control is performed at the time of overflow. However, other modifications that can be made by those skilled in the art can be added. Further, under the assumption that no overflow condition occurs, it is sufficient to perform normal ring buffering control. Further, for example, a buffer configuration other than the ring buffer can be adopted, and other well-known procedures for storing / reading history information can also be adopted.

1 is a diagram illustrating a schematic configuration of a CAN device according to a first embodiment of the present invention. It is a figure for demonstrating the structure of the message handling part which concerns on the 1st Embodiment of this invention. It is a figure showing the structure of the message buffer and ring buffer which concern on the 1st Embodiment of this invention. It is a figure showing the flow of the process at the time of the reception interruption in a CAN device in the 1st Embodiment of this invention. It is a timing chart showing operation of this embodiment. It is a figure showing another structure of the message buffer and ring buffer which concern on the 1st Embodiment of this invention. It is a figure for demonstrating operation | movement of one Example of this invention. It is a figure for demonstrating operation | movement of one Example of this invention. It is a figure for demonstrating operation | movement of one Example of this invention. It is a figure for demonstrating operation | movement of one Example of this invention. It is a figure for demonstrating operation | movement of one Example of this invention. It is a figure showing the schematic structure of CAN (Controller Area Network). It is a figure showing the structure of the message buffer with which a CAN module is equipped. It is a flowchart showing the operation | movement after reception interruption generation | occurrence | production when a message is received. It is a timing chart for demonstrating a prior art.

Explanation of symbols

2 Message handling unit 3 Message buffer 4 CAN protocol transmission layer 5 Mask set 6, 61, 62 Ring buffer 11, 1n, 16, 19 CAN module (CAN controller)
20 Search common address generator 21 CAN write pointer 22 Latest history information pointer 23 Oldest (unread) history information pointer 24 History invalid flag 25 Overflow flag 40 CPU I / F
51 CPU
52 RAM
53 Peripheral circuit 60 CAN transceiver 100 CAN device

Claims (18)

A data processing module having a message buffer connected to a multi-master network and having a plurality of buffers capable of storing one message, and a history buffer capable of storing history information indicating the position of the buffer on the message buffer a predetermined number of times A method for managing sent and received messages in
And storing the message handling unit of the data processing module, the position information of the buffer has been updated on the message buffer, the next write position in the history buffer,
The message handling unit sequentially updating an unread pointer indicating a position of unreferenced history information from the CPU in the history buffer in response to a read access from a CPU (Central Processing Unit),
Holding at least the latest write position of the history buffer and the unread pointer so that the CPU can refer to them,
A method for managing transmitted and received messages in a data processing module. The step of storing the position information of the buffer in the history buffer stores the position information of the buffer that has been updated in response to an update of a buffer value of the message buffer. Item 4. A method for managing transmission / reception messages in the data processing module according to Item 1. The message handling unit has a latest history information pointer that indicates a position immediately before a writing position in the history buffer,
Making it possible to refer to the latest history information pointer from the CPU;
The transmission / reception message management method in the data processing module according to claim 1 or 2. The message handling unit includes a history invalid flag indicating whether or not history information is stored in the history buffer;
The message handling unit, the history invalid flag in the initial state the next write position and unread pointer of the history buffer to match set to the ON state at the stage where the next write position and unread pointer of the history buffer is not matched Set the history invalid flag to an off state,
The CPU refers to the history invalid flag to determine whether or not history information is stored in the history buffer;
The transmission / reception message management method in the data processing module according to any one of claims 1 to 3 . The message handling unit has an overflow flag indicating that the history buffer has run out of free space;
The message handling unit sets the overflow flag to an on state in a state where the next write position of the history buffer and the position immediately before the unread pointer match.
When the overflow flag is in an on state, the message handling unit overwrites the latest history information at the latest write position of the history buffer;
The method for managing transmission / reception messages in the data processing module according to claim 1 . The transmission / reception message management method in the data processing module according to claim 1, wherein a ring buffer is used as the history buffer. A message buffer having a plurality of buffers capable of storing one message ;
A message handling unit that scans the message buffer based on an identifier (ID) of the received message when a message is received, and selects a buffer for storing the received message from the plurality of buffers;
A history buffer that holds an address of a buffer in which received messages are stored among the plurality of buffers and manages an order in which the received messages are received;
A data processing module. A data processing circuit for reading data from the message buffer based on the order of reception of the received messages managed in the history buffer;
The data processing module according to claim 7 . An oldest history information pointer indicating the oldest buffer for managing received messages stored in the history buffer;
A write pointer indicating a position for storing the address of the buffer selected by the message handling unit,
The data processing module according to claim 7 or 8 . A data protection circuit is provided that protects the order of writing to the history buffer from the top to a predetermined order by returning the address of the write pointer to a predetermined address when the free capacity of the history buffer becomes a predetermined value or less. ,
The data processing module according to claim 9 . The history buffer is constituted by a ring buffer;
The data processing module according to any one of claims 7 to 10 . In a data processing module connected to a multi-master network,
A message buffer having a plurality of buffers capable of storing a message to be transmitted and a received message;
A history buffer capable of storing history information indicating the position of the buffer on which update has been performed on the message buffer for a predetermined number of times;
A message handling unit for managing messages on the message buffer and storing buffer position information of the message buffer in the history buffer ;
The message handling unit, a write position pointer indicating a write position of the history information on the history buffer;
In response to a read access from a CPU (Central Processing Unit), an unread pointer indicating the position of history information that has not been referenced from the CPU in the history buffer,
Holding at least the latest write position of the history buffer and the unread pointer so that the CPU can refer to them,
A data processing module. The data processing module according to claim 12 ,
At least the history buffer, the write position pointer, and the unread pointer are individually provided for transmission message management and reception message management,
A data processing module. A message buffer having a plurality of buffers capable of storing a message to be transmitted and a received message;
A ring buffer capable of storing history information indicating the position of the buffer where the update has been performed on the message buffer for a predetermined number of times;
A message handling unit for managing messages on the message buffer;
The message handling unit includes a write position pointer indicating a write position of the history information on the ring buffer;
In response to a read access from a CPU (Central Processing Unit), an unread pointer that indicates a position of history information that is not referenced from the CPU in the ring buffer,
Holding at least the latest write position of the ring buffer and the unread pointer so that they can be referred to by the CPU;
A data processing module. 15. The data processing module according to claim 14 , further comprising:
A latest history information pointer indicating a position immediately before the writing position to the ring buffer;
Making it possible to refer to the latest history information pointer from the CPU;
A data processing module. The data processing module according to claim 14 or 15 , further comprising:
The message handling unit is set to an on state in an initial state where the next write position of the ring buffer matches an unread pointer, and is set to an off state when the next write position of the ring buffer and an unread pointer do not match. Has a history invalid flag,
The CPU refers to the history invalid flag to determine whether or not history information is stored in the ring buffer;
A data processing module. The data processing module according to any one of claims 14 to 16 , further comprising:
The message handling unit has an overflow flag that is set to an on state in a state where the next write position of the ring buffer and the position before the unread pointer match.
The message handling unit
If the overflow flag is on, overwriting the latest history information at the latest write position of the ring buffer;
A data processing module. The data processing module according to any one of claims 14 to 17 ,
At least the ring buffer, the write position pointer, the unread pointer, the history invalid flag, and the overflow flag are individually provided for transmission message management and reception message management,
A data processing module.

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