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Method for identifying CAN communication pin baud rate of OBD port of commercial vehicle

A CAN communication and baud rate technology, applied in the field of Internet of Vehicles, can solve the problem of unable to judge the pin communication vehicle and other problems

Inactive Publication Date: 2019-03-15
SHANGHAI XINGRONG AUTOMOBILE TECH CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] In order to solve the above-mentioned problems in the prior art, the present invention proposes an intelligent identification of the CAN line baud rate to match different pin communications for different computer versions, aiming to solve the problem of fast access to the system and help the maintenance master solve the problem of manual judgment through tools. Select the corresponding pin communication, especially the non-standard communication pin defined by the whole vehicle and the market data are not public, and the vehicle that cannot judge the pin communication can realize the intelligent judgment of the communication pin and quickly enter the vehicle diagnosis mode

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  • Method for identifying CAN communication pin baud rate of OBD port of commercial vehicle

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Embodiment Construction

[0021] The present invention will be further illustrated by the following examples, the purpose of which is only to better understand the research content of the present invention and not to limit the protection scope of the present invention.

[0022] The baud rate is the number of bits per second (bits / second) that can be sent in serial communication. The MCS-51 serial port has different baud rate calculation methods in four operating modes. Among them, the baud rate calculation of mode 0 and mode 2 is very simple; the baud rate selection of mode 1 and mode 3 are the same, so only the working mode 1 is used as an example to illustrate the selection of the baud rate of serial communication.

[0023] When the serial port works in mode 1, its baud rate will be generated by timer / counter 1. Usually, the timer is set to work in mode 2 (automatic addition mode). The baud rate calculation formula in this mode is:

[0024] Baud rate = (1+SMOD)*crystal frequency / (384*(256-TH1))

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Abstract

The invention provides a method for identifying the CAN communication pin baud rate of an OBD port of a commercial vehicle. The method comprises the following steps of 1, collecting pin voltage of each pin of the OBD port; 2, judging whether or not the voltage value of each pin stays in an effective range of CANH and CANL, wherein the pins in the effective range are CAN communication pins; 3, sending a string of 1-bit waveforms to the OBD port of the commercial vehicle and sending a reply waveform through an ECU computer board of the commercial vehicle; 4, acquiring a time interval of every two 1-bit sites in the reply waveform; 5, conducting calculation according to a formula and obtaining a baud rate range of the CAN communication pins, wherein the formula is represented as the baud rate= (1 + SMOD) * crystal oscillation frequency / (384 * (256-TH1)), SMOD refers to the seventh site of a register PCON and is called as a baud rate multiplication site, and TH1 refers to the time interval. By means of the method, the communication pins of the non-standard vehicle OBD port can be intelligently detected, the failure situation that a maintainer cannot access to a diagnosis mode and thusthe vehicle cannot be repaired is reduced, and a CAN communication process is prevented from disturbing interaction of other CAN templates.

Description

technical field [0001] The invention relates to the technical field of Internet of Vehicles, in particular to a method for identifying the baud rate of a CAN communication pin of an OBD port of a commercial vehicle. Background technique [0002] Commercial vehicles refer to all trucks, special vehicles, military vehicles, engineering vehicles, all passenger cars with more than nine seats, tractors, agricultural vehicles, mining vehicles, etc. In short, commercial vehicles are for profit, generally trucks or large and medium-sized passenger cars. Existing cars will have an OBD interface. OBD is the abbreviation of On-Board Diagnostic in English and translated into "on-board diagnostic system" in Chinese. Therefore, the OBD interface is the interface of the on-board diagnostic system. [0003] With the development of domestic vehicle technology, more and more manufacturers have joined the field of commercial vehicles. Different manufacturers also define their own brand-speci...

Claims

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Application Information

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IPC IPC(8): G05B23/02H04L29/08
CPCG05B23/0213G05B2219/24065H04L67/12
Inventor 蔡继业刘吉王奥运
Owner SHANGHAI XINGRONG AUTOMOBILE TECH CO LTD
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