Message transceiving method and system for car CAN bus gateway

Abstract

The invention discloses a message transceiving method and system for a car CAN bus gateway. The method comprises the steps of defining a software receiving buffer and a software transmitting buffer, wherein the software receiving buffer is managed by a message receiving interrupt service routine and a software receiving buffer management sub-module, the software transmitting buffer is managed by a message transmitting function, a message transmitting interrupt service routine and a software transmitting buffer management sub-module, and the software transmitting buffer management sub-module and the software receiving buffer management sub-module form a software buffer management module; in the software buffer management module, if a signal is received, judging whether the signal indicates that a new message is received or not, and if the signal indicates that the new message is received, entering the software receiving buffer management sub-module; otherwise, judging whether the received signal indicates that a hardware transmitting buffer is not full or not, and if the received signal indicates that the hardware transmitting buffer is not full, entering the software transmitting buffer management sub-module. According to the method and the system, through combination of the software buffer and the hardware buffer of a CAN controller, a message can be received in real time, and it is ensured that the message is not lost.

Description

technical field [0001] The invention belongs to the technical field of automotive electronics, and more specifically relates to a message sending and receiving method and system for an automotive CAN bus gateway. Background technique [0002] With the increase of automotive electronic components and the improvement of intelligence, the CAN bus system has become an important part of the car. According to the different requirements of functional division, topology design and real-time performance, automobiles generally design multiple CAN networks. The information exchange between CAN networks is realized by the gateway, which includes multiple CAN interfaces, accessing different CAN networks, and realizing the reception and forwarding of messages. Among all CAN network nodes, the gateway has the highest load from the perspective of message reception and transmission. [0003] The CAN network uses non-destructive arbitration to compete for the bus. Any node can send data to ...

AI Technical Summary

Problems solved by technology

The hardware receiving buffer and hardware sending buffer of the internal CAN controller of the low-cost MCU are very small. When a large number of messages appear on the CAN network in a short period of time, if the data in the hardware receiving buffer cannot be read in time and cleared flag bit, it will not be able to receive new messages

When the CAN gateway needs to forward a large number of messages in a short period of time, if the hardware sending buffer is full but there are still messages to be sent, if the messages cannot be forwarded in time, it may cause missed messages or inaccurate cycles mistake

If you choose an MCU with a relatively large hardware receiving buffer and hardware sending buffer for the CAN controller, it will increase the cost and affect economic and social benefits

[0005] Chinese invention patent: A method and device for sending CAN bus messages in a controller area network (application number: 201610064343.3), which introduces a method for configuring the message sending time of each CAN node, avoiding the simultaneous sending of multiple nodes Messages lead to bus contention and too dense messages

This method can improve the distribution of bus messages on the time axis and reduce the requirements for the CAN controller hardware buffer, but this method needs to analyze the bus baud rate, the priority and cycle of all messages in the network, not only need Each CAN node implements this method, and the flexibility is very poor. Once a node is added or reduced due to changes in the network topology, it will affect the entire design

[0006] Chinese invention patent: data transmission method between CAN bus gateway controller and CAN bus (application number: 200710075363.1), using the method of periodically scanning the data buffer to determine whether there is a data packet to be sent, in many cases, there is no need The sent data packets are still periodically scanned at this time, which will waste valuable computing resources of the embedded system

In addition, if the scan cycle time is set longer, the short-period messages that need to be forwarded will not meet the cycle accuracy requirements, and if the scan cycle time is set shorter, the system load will be increased

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