A LIN communication anti-interference method and circuit

Abstract

The present invention discloses a LIN communication anti-interference method and circuit thereof, which calculates the bit length and expected jump point of the start bit through the baud rate, then detects and judges the received data of the start bit through the first receiving window and the second receiving window, and filters, shapes and fills the interference and noise. The method solves the problem that the data error caused by noise interference during the operation of the existing LIN bus circuit leads to the error of received data, and ensures the correctness and reliability of data communication.

Description

Technical Field

[0001] The invention relates to an anti-interference method and a circuit thereof, in particular to a LIN communication anti-interference method and a circuit thereof, belonging to the technical field of semiconductor integrated circuits. Background Art

[0002] LIN is the abbreviation of Local Interconnect Network. It is a low-cost serial communication protocol that is widely used in many fields such as automobiles, home appliances, and office equipment. The LIN bus is often used as a message-based communication bus protocol, especially in automobiles.

[0003] However, due to the influence of environmental noise, especially in complex environments such as automobiles, noise may cause the level value of the LIN bus to change, causing the LIN communication device to misjudge when receiving data, ultimately leading to LIN bus communication failure. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a LIN communication anti-interference method and circuit thereof, so as to solve the problem that during the operation of the existing LIN bus circuit, data errors are caused by noise interference, resulting in received data errors.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A LIN communication anti-interference method comprises the following steps:

[0007] S1, the system is in standby mode, waiting to receive data;

[0008] S2, when the system detects the first falling edge, it determines whether the first falling edge is the start position; if it is the start position, it goes to step S3, if not, it returns to step S1;

[0009] S3, the system opens the first receiving window, the filter width of the first receiving window is 1 / 3 bit, the first receiving window detects the level value of the received data, when the level value of the received data jumps, the first receiving window makes the level value of the received data follow the level value that did not jump at the previous moment, when the level value of the received data does not jump, the first receiving window does not act;

[0010] S4: When the system receives the 2 / 3 bit start bit, the first receiving window is closed and the second receiving window is opened;

[0011] S5, the system calculates the expected jump point through the baud rate, and the second receiving window detects the level value of the received data. The moment when the level value of the received data jumps is defined as the actual jump point. When the actual jump point is before the expected jump point, the system goes to step S6. When the actual jump point coincides with the expected jump point, the system goes to step S7. When the actual jump point is after the expected jump point, the system returns to step S1.

[0012] S6, the second receiving window determines that the actual jump point is before the expected jump point, and the second receiving window makes the level value of the received data after the actual jump point follow the level value that did not jump at the previous moment;

[0013] S7. After the system receives the actual jump point, it determines whether the level value after the actual jump point jumps. If no jump occurs, the second receiving window does not operate. If a jump occurs, the second receiving window will receive the data level value that follows the level value that did not jump at the previous moment and return to step S3.

[0014] Furthermore, the determination of whether the first falling edge is a start bit is specifically that the system starts timing when it receives the first falling edge, and the system determines whether the duration t1 of the first falling edge is greater than 1 / 3 of the bit time. If the duration t1 of the first falling edge is greater than or equal to 1 / 3 of the bit time, then the first falling edge is determined to be a start bit; if the duration t1 of the first falling edge is less than 1 / 3 of the bit time, then the first falling edge is determined not to be a start bit.

[0015] Furthermore, the bit time is calculated from the baud rate of the system.

[0016] Furthermore, the second receiving window includes a first window period and a second window period, and the filtering widths of the first window period and the second window period are 1 / 3 bit respectively.

[0017] Furthermore, the first window period of the second receiving window in step S6 works, and the second window period of the second receiving window in step S7 works.

[0018] A LIN communication anti-interference circuit comprises a data shaping filter, a data receiver, a data transmitter, a baud rate controller, an operational amplifier and a resistor, wherein the input end of the data shaping filter is connected to one end of the resistor and connected to an input signal LIN_IN, the output end of the data shaping filter is connected to the input end of the data receiver and generates a signal RX, the output end of the data receiver is connected to the input end of the data transmitter, the first output end of the data transmitter is connected to the enable end of the operational amplifier and generates a control signal TX_EN, the second output end of the data transmitter is connected to the input end of the operational amplifier and generates a signal TX, the output end of the operational amplifier is connected to the other end of the resistor and generates an output signal LIN_OUT, and the data shaping filter executes a LIN communication anti-interference method.

[0019] Compared with the prior art, the present invention has the following advantages and effects:

[0020] 1. The present invention can effectively filter out noise interference and perform waveform shaping processing, thereby ensuring the correctness and reliability of data communication;

[0021] 2. The first receiving window and the second receiving window of the present invention can be dynamically adjusted to optimize the filtering effect according to the change of the actual baud rate, so as to ensure that noise can be effectively filtered out at different transmission rates;

[0022] 3. In the filtering process of the present invention, the system not only filters out noise, but also performs shaping and padding processing on the waveform. Even if some bits are distorted or lost due to noise, the original form can be restored through shaping and padding, thereby ensuring the integrity of the data;

[0023] 4. Through the double filtering superposition of the first receiving window and the second receiving window, the system can resist noise interference at multiple levels. The multi-level filtering mechanism not only improves the anti-interference ability, but also further enhances the accuracy and stability of data communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention discloses a flow chart of a LIN communication anti-interference method.

[0025] Figure 2 It is a waveform diagram of a LIN communication anti-interference method of the present invention.

[0026] Figure 3 The invention discloses a receiving data window diagram of a LIN communication anti-interference method.

[0027] Figure 4 It is a schematic diagram of a LIN communication anti-interference circuit of the present invention. DETAILED DESCRIPTION

[0028] In order to elaborate on the technical scheme adopted by the present invention to achieve the predetermined technical purpose, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only partial embodiments of the present invention, rather than all embodiments, and the technical means or technical features in the embodiments of the present invention can be replaced without paying creative work. The present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0029] like Figure 1 As shown, a LIN communication anti-interference method of the present invention comprises the following steps:

[0030] S1. The system is in standby mode, waiting to receive data.

[0031] S2. When the system detects the first falling edge, it determines whether the first falling edge is the start position; if it is the start position, it goes to step S3; if not, it returns to step S1.

[0032] Among them, judging whether the first falling edge is the start bit is specifically as follows: Figure 2 and Figure 3 As shown, the system starts timing when it receives the first falling edge, and the system determines whether the duration t1 of the first falling edge is greater than 1 / 3 of the bit time. If the duration t1 of the first falling edge is greater than or equal to 1 / 3 of the bit time, the first falling edge is determined to be the start bit. If the duration t1 of the first falling edge is less than 1 / 3 of the bit time, the first falling edge is determined not to be the start bit.

[0033] The bit time is calculated from the baud rate of the system. The baud rate refers to the number of signal elements transmitted per unit time in digital communication, and is usually used to describe the rate of serial communication. When the signal has only two states, 0 and 1, the baud rate is equal to the bit rate, so the bit time in this embodiment is the reciprocal of the baud rate. The end time of the bit time of a whole bit is the time of the expected jump point required later.

[0034] S3. The system opens the first receiving window. The filter width of the first receiving window is 1 / 3 bit. The first receiving window detects the level value of the received data. When the level value of the received data jumps, the first receiving window will follow the level value of the received data to the level value that did not jump at the previous moment. When the level value of the received data does not jump, the first receiving window does not act.

[0035] S4. When the system receives the 2 / 3 bit start bit, the first receiving window is closed and the second receiving window is opened. The second receiving window includes a first window period and a second window period, and the filter widths of the first window period and the second window period are 1 / 3 bit respectively.

[0036] S5. The system calculates the expected jump point through the baud rate. The second receiving window detects the level value of the received data. The moment when the level value of the received data jumps is defined as the actual jump point. When the actual jump point is before the expected jump point, the system goes to step S6. When the actual jump point coincides with the expected jump point, the system goes to step S7. When the actual jump point is after the expected jump point, the system returns to step S1.

[0037] S6. The second receiving window works during the first window period. The second receiving window determines that the actual jump point is before the expected jump point. The second receiving window makes the level value of the received data after the actual jump point follow the level value that did not jump at the previous moment.

[0038] S7, after the second window period working system of the second receiving window receives the actual jump point, it determines whether the level value after the actual jump point jumps. If no jump occurs, the second receiving window does not act. If a jump occurs, the second receiving window will receive the data level value that follows the level value that did not jump at the previous moment and return to step S3.

[0039] like Figure 3 As shown, a LIN communication anti-interference circuit includes a data shaping filter, a data receiver, a data transmitter, a baud rate controller, an operational amplifier and a resistor, wherein the input end of the data shaping filter is connected to one end of the resistor and connected to the input signal LIN_IN, the output end of the data shaping filter is connected to the input end of the data receiver and generates a signal RX, the output end of the data receiver is connected to the input end of the data transmitter, the first output end of the data transmitter is connected to the enable end of the operational amplifier and generates a control signal TX_EN, the second output end of the data transmitter is connected to the input end of the operational amplifier and generates a signal TX, the output end of the operational amplifier is connected to the other end of the resistor and generates an output signal LIN_OUT, and the data shaping filter performs a LIN communication anti-interference method.

[0040] The present invention can effectively filter out noise interference and perform waveform shaping processing, thereby ensuring the correctness and reliability of data communication; the first receiving window and the second receiving window of the present invention can optimize the filtering effect according to the change of the actual baud rate through dynamic adjustment, ensuring that the noise can be effectively filtered out at different transmission rates; in the filtering process of the present invention, the system can not only filter out the noise, but also perform waveform shaping and padding processing, even if some bits are distorted or lost due to noise, the original form can be restored through shaping and padding, thereby ensuring the integrity of the data; through the double filtering superposition of the first receiving window and the second receiving window, the system can resist noise interference at multiple levels, and the multi-level filtering mechanism not only improves the anti-interference ability, but also further enhances the correctness and stability of data communication.

[0041] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement made to the above embodiments without departing from the content of the technical solution of the present invention, based on the technical essence of the present invention, within the spirit and principles of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims

1. A LIN communication anti-interference method, characterized in that The following steps are involved: S1, the system is in standby mode, waiting to receive data; S2, when the system detects the first falling edge, it determines whether the first falling edge is the start position; if it is the start position, it goes to step S3, if not, it returns to step S1; S3, the system opens the first receiving window, the filter width of the first receiving window is 1 / 3 bit, the first receiving window detects the level value of the received data, when the level value of the received data jumps, the first receiving window makes the level value of the received data follow the level value that did not jump at the previous moment, when the level value of the received data does not jump, the first receiving window does not act; S4: When the system receives the 2 / 3 bit start bit, the first receiving window is closed and the second receiving window is opened; S5, the system calculates the expected jump point through the baud rate, and the second receiving window detects the level value of the received data. The moment when the level value of the received data jumps is defined as the actual jump point. When the actual jump point is before the expected jump point, the system goes to step S6. When the actual jump point coincides with the expected jump point, the system goes to step S7. When the actual jump point is after the expected jump point, the system returns to step S1. S6, the second receiving window determines that the actual jump point is before the expected jump point, and the second receiving window makes the level value of the received data after the actual jump point follow the level value that has not jumped at the previous moment; S7. After the system receives the actual jump point, it determines whether the level value after the actual jump point jumps. If no jump occurs, the second receiving window does not operate. If a jump occurs, the second receiving window will receive the data level value that follows the level value that did not jump at the previous moment and return to step S3.

2. A LIN communication anti-interference method according to claim 1, characterized in that: The determination of whether the first falling edge is the start bit is specifically as follows: the system starts timing when it receives the first falling edge, and the system determines whether the duration t1 of the first falling edge is greater than 1 / 3 of the bit time. If the duration t1 of the first falling edge is greater than or equal to 1 / 3 of the bit time, then the first falling edge is determined to be the start bit; if the duration t1 of the first falling edge is less than 1 / 3 of the bit time, then the first falling edge is determined not to be the start bit.

3. A LIN communication anti-interference method according to claim 2, characterized in that: The bit time is calculated from the baud rate of the system.

4. A LIN communication anti-interference method according to claim 1, characterized in that: The second receiving window includes a first window period and a second window period, and the filtering widths of the first window period and the second window period are 1 / 3 bit respectively.

5. A LIN communication anti-interference method according to claim 4, characterized in that: The first window period of the second receiving window in step S6 works, and the second window period of the second receiving window in step S7 works.

6. A LIN communication anti-interference circuit, characterized in that: The invention comprises a data shaping filter, a data receiver, a data transmitter, a baud rate controller, an operational amplifier and a resistor, wherein the input end of the data shaping filter is connected to one end of the resistor and connected to an input signal LIN_IN, the output end of the data shaping filter is connected to the input end of the data receiver and generates a signal RX, the output end of the data receiver is connected to the input end of the data transmitter, the first output end of the data transmitter is connected to the enable end of the operational amplifier and generates a control signal TX_EN, the second output end of the data transmitter is connected to the input end of the operational amplifier and generates a signal TX, the output end of the operational amplifier is connected to the other end of the resistor and generates an output signal LIN_OUT, and the data shaping filter executes the LIN communication anti-interference method described in any one of claims 1 to 5.

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