MCU wake-up circuit and wake-up method based on CAN communication

Abstract

The invention relates to the technical field of data transmission unit hardware circuit design, in particular to an MCU wake-up circuit based on CAN communication and a wake-up method.The MCU wake-up circuit comprises a voltage division module, a signal input module and a circuit comparison module, and the voltage division module is connected with the inverted input end of the circuit comparison module through the signal input module; the CAN0H is connected with the positive input end of a circuit comparison module through a signal input module, the circuit comparison module is connected with a power supply VCC, the output end of the circuit comparison module is connected with an MCU, when the voltage of the positive input end is larger than that of the inverted input end, the circuit comparison module outputs a first signal, and when the voltage of the positive input end is smaller than that of the inverted input end, the circuit comparison module outputs a second signal. The circuit comparison module outputs a second signal. According to the CAN bus wake-up signal identification circuit, effective identification of CAN bus wake-up signals is achieved through a simple resistance voltage division and voltage comparison structure, and the CAN bus wake-up signal identification circuit is compact in circuit structure, sensitive in response, good in anti-interference capacity and low in power consumption.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of data transmission unit hardware circuit design, in particular to an MCU awakening circuit and method based on CAN communication. BACKGROUND

[0002] In an application scenario such as a data transmission unit (DTU), in order to reduce power consumption, a master control chip (such as an STM32L431) is often in a sleep state, and a specific awakening mechanism is required to respond to external communication. As a commonly used communication mode, a CAN bus needs a reliable circuit to convert a CAN communication signal into a level change that can awaken the master control chip. Traditional awakening circuits have problems such as inaccurate signal identification and weak anti-interference capability, which affect system reliability and power consumption control, therefore, it is of great significance to design a precise and stable CAN awakening circuit and method. SUMMARY

[0003] The application aims to solve the problems in the background art and provides an MCU awakening circuit and method based on CAN communication.

[0004] In order to achieve the above-mentioned purpose, the application adopts the following technical scheme:

[0005] An MCU awakening circuit based on CAN communication comprises a voltage division module, a signal input module and a circuit comparison module, the voltage division module is connected to the inverting input end of the circuit comparison module through the signal input module, CAN0H is connected to the forward input end of the circuit comparison module through the signal input module, the circuit comparison module is connected to a power supply VCC, and the output end of the circuit comparison module is connected to an MCU; when the voltage of the forward input end is greater than that of the inverting input end, the circuit comparison module outputs a first signal; and when the voltage of the forward input end is less than that of the inverting input end, the circuit comparison module outputs a second signal.

[0006] The voltage division module comprises resistors R29 and R31, one end of the resistor R29 is connected to the power supply VCC, and one end of the resistor R31 is connected to one end of the resistor R29; the other end of the resistor R31 is connected to GND; and the circuit part between the resistors R29 and R31 is connected to the circuit comparison module.

[0007] The signal input module comprises resistors R25 and R15, one end of the resistor R25 is connected to the circuit part between the resistors R29 and R31, the other end of the resistor R25 is connected to the inverting input end of the circuit comparison module, one end of the resistor R15 is connected to CAN0H, and the other end of the resistor R15 is connected to the forward input end of the circuit comparison module.

[0008] The circuit comparison module comprises a comparator U10, the comparator U10 has an inverting input end, a forward input end, a power supply connection end, a ground end, an output end, one end of a capacitor C26 connected between the power supply connection end and the power supply VCC, and the other end of the capacitor C26 is connected to GND.

[0009] The output end of the comparator U10 is connected to one end of a resistor R27, and the other end of the resistor R27 is connected to the power supply VCC.

[0010] The wake-up circuit comprises resistors R29, R31, R25, R15, R27, a capacitor C26 and a comparator U10, the resistor R29 has a resistance of 36KΩ, the resistor R31 has a resistance of 10KΩ, the resistor R25 has a resistance of 1KΩ, the resistor R15 has a resistance of 1KΩ, the resistor R27 has a resistance of 10KΩ, the capacitor C26 is 100nF, and the comparator U10 is AP331AWG-7.

[0011] A wake-up method of an MCU wake-up circuit based on CAN communication, wherein a reference voltage is formed by dividing the power supply VCC through a voltage division module, and is sent to the inverting input end of a comparator through a signal input module;

[0012] The high-level signal CAN0H of the CAN bus is sent to the forward input end of the comparator after being processed by the signal input module;

[0013] The comparator compares the voltage between the forward input end and the inverting input end, and outputs a first signal when the voltage of the forward input end is higher than that of the inverting input end;

[0014] The comparator outputs a second signal when the voltage of the forward input end is lower than that of the inverting input end;

[0015] The GPIO pin of the MCU receives the first signal or the second signal output by the comparator and triggers the MCU to wake up from the sleep state and enter the working mode to respond to the CAN communication.

[0016] The MCU wake-up circuit and the wake-up method based on CAN communication have the beneficial effects that: the wake-up signal of the CAN bus can be effectively recognized through the simple resistor voltage division and voltage comparison structure, the circuit structure is compact and responsive, has good anti-interference ability and low power consumption characteristics, the comparison logic is clear, the CAN bus silent state and the wake-up state can be accurately distinguished, the reliability and stability of the MCU wake-up are ensured, and the intelligent control level and the energy utilization efficiency of the system are effectively improved. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is a CNA wake-up circuit schematic diagram of an embodiment of the application;

[0018] Figure 2 For an embodiment of the application, the STM32L431 pin wiring diagram. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application.

[0020] Reference Figure 1 , Figure 2 A CAN communication-based MCU wake-up circuit, comprising a voltage division module, a signal input module, and a circuit comparison module, the voltage division module being connected to the inverting input end of the circuit comparison module through the signal input module, CAN0H being connected to the forward input end of the circuit comparison module through the signal input module, the circuit comparison module being connected to a power supply VCC, and the output end of the circuit comparison module being connected to an MCU, wherein when the voltage at the forward input end is greater than that at the inverting input end, the circuit comparison module outputs a first signal, and when the voltage at the forward input end is less than that at the inverting input end, the circuit comparison module outputs a second signal.

[0021] The reference voltage signal generated by dividing the power supply VCC is sent to the inverting input end of the circuit comparison module through the signal input module, and the signal from the CAN bus high-level line CAN0H is sent to the forward input end of the circuit comparison module through the signal input module, thereby constructing a wake-up control logic based on voltage comparison.

[0022] When the device is in a silent or dormant state, the CAN0H signal remains at a high level, and its voltage is higher than the reference voltage at the inverting input end, so the circuit comparison module outputs the first signal, and the MCU remains in a dormant state. When a communication fluctuation or wake-up event occurs in the CAN bus, the CAN0H signal level decreases, causing its input voltage to be lower than the reference voltage at the inverting input end. At this time, the circuit comparison module outputs the second signal, which is transmitted to the MCU wake-up pin, thereby triggering the MCU to exit the dormant state and enter the working state, and completing the wake-up operation.

[0023] The application realizes effective recognition of the CAN bus wake-up signal through a simple resistance voltage division and voltage comparison structure, and has a compact circuit structure, sensitive response, good anti-interference ability, and low power consumption. The comparison logic is clear, and can accurately distinguish between the silent state and the wake-up state of the CAN bus, ensuring the reliability and stability of the MCU wake-up, and effectively improving the intelligent control level and energy utilization efficiency of the system.

[0024] The voltage dividing module comprises a resistor R29 and a resistor R31, one end of the resistor R29 is connected to a power supply VCC, one end of the resistor R31 is connected to one end of the resistor R29, the other end of the resistor R31 is connected to GND, and the circuit between the resistor R29 and the resistor R31 is connected to the circuit comparison module.

[0025] As an embodiment, the voltage dividing module is composed of a resistor R29 (36KΩ1%) and a resistor R31 (10KΩ1%), and a VCC3_3 power supply is divided by the voltage dividing module to provide a reference level basis for the subsequent comparison circuit. By reasonably matching the resistance values, a voltage signal suitable for comparison requirements is stably output.

[0026] The voltage dividing module is composed of a resistor R29 and a resistor R31 connected in series, one end of the resistor R29 is connected to a power supply VCC, the other end of the resistor R31 is connected to GND, and the connection point between the resistor R29 and the resistor R31 forms a stable intermediate voltage. The voltage value is determined by the resistance ratio of the resistor R29 and the resistor R31, and is input as a reference voltage to the input end of the circuit comparison module.

[0027] During the operation of the circuit, the reference voltage is a fixed value and does not fluctuate with the change of the CAN bus level, providing a stable reference for voltage comparison, so that the circuit comparison module can accurately determine whether the level change from the CAN bus reaches the wake-up condition. The voltage dividing module composed of the resistor R29 and the resistor R31 can provide a stable and reliable reference voltage signal without the need for additional voltage stabilizing devices, simplifying the circuit structure, reducing system power consumption, and improving the accuracy of voltage comparison. At the same time, this structure has strong anti-interference ability and can maintain stable output voltage in complex electromagnetic environments, providing protection for the sensitivity and reliability of the entire wake-up circuit.

[0028] The signal input module comprises a resistor R25 and a resistor R15, one end of the resistor R25 is connected to the circuit between the resistor R29 and the resistor R31, the other end of the resistor R25 is connected to the inverting input end of the circuit comparison module, one end of the resistor R15 is connected to CAN0H, and the other end of the resistor R15 is connected to the positive input end of the circuit comparison module.

[0029] The CAN0H signal is sequentially connected to the in-phase input end of U10 (U10 (AP331AWG-7)) through resistors R25 (1KΩ1%) and R15 (1KΩ1%), realizing transmission and preliminary current limiting protection of the CAN communication signal and avoiding signal impact on circuit stability.

[0030] The signal input module is composed of the resistor R25 and the resistor R15, and is used for transmitting the reference voltage and the CAN communication signal to the circuit comparison module respectively. One end of the resistor R25 is connected to the middle node of the resistors R29 and R31 in the voltage division module, and the other end is connected to the inverting input end of the circuit comparison module, which is used for introducing the stable reference voltage. One end of the resistor R15 is connected to the high level signal line CAN0H of the CAN bus, and the other end is connected to the forward input end of the circuit comparison module, which is used for transmitting the real-time communication level signal.

[0031] When the CAN0H is in the normal silence state, the voltage is high, the signal input module applies the voltage to the forward input end of the comparison module through the R15, so that the voltage is higher than the reference voltage of the inverting end, and the comparator outputs the first signal. When the CAN bus has a communication activity or a wake-up event, the CAN0H level decreases, and the voltage transmitted to the forward input end through the R15 also decreases. Once the voltage is lower than the reference voltage of the inverting input end, the circuit comparison module outputs the second signal, so as to realize the effective identification and transmission of the CAN wake-up signal.

[0032] The signal input module realizes the reliable transmission of the reference voltage and the CAN real-time signal through the reasonable configuration of the resistors R25 and R15, and has the current limiting protection function, so as to effectively avoid the influence of external signal interference on the input of the circuit comparison module, and improve the system stability and the anti-interference ability.

[0033] The circuit comparison module includes the comparator U10, the comparator U10 has the inverting input end, the forward input end, the power supply connection end, the ground end and the output end, one end of the capacitor C26 connected between the power supply connection end and the power supply VCC, and the other end of the capacitor C26 is connected to GND; one end of the resistor R27 connected to the output end of the comparator U10, and the other end of the resistor R27 is connected to the power supply VCC.

[0034] The comparator U10 constitutes the voltage comparison circuit, the inverting input end is connected to the output signal of the voltage division module, the same phase input end is connected to the signal processed by the resistor of the CAN0H, the power supply end is supplied by the VCC3_3 and is filtered by the capacitor C26 (100nF), so as to guarantee the stable power supply; the output end is connected to the VCC3_3 through the pull-up resistor R27 (10KΩ1%), and outputs the MCU_WAKEUP signal to the GPIO PA0 pin of the STM32L431, so as to utilize the high gain and high sensitivity characteristics of the U10, accurately compare the input signal and the reference level, and output the level change signal.

[0035] As an embodiment, the wake-up circuit includes resistors R29, R31, R25, R15, R27, capacitor C26, and comparator U10. The resistance value of R29 is 36KΩ, the resistance value of R31 is 10KΩ, the resistance value of R25 is 1KΩ, the resistance value of R15 is 1KΩ, the resistance value of R27 is 10KΩ, the capacitor C26 is 100nF, and the comparator U10 is AP331AWG-7.

[0036] When there is CAN communication, the CAN0H signal generates a level change, which is input to the U10 through R15. The U10 compares the levels at the two terminals and outputs the MCU_WAKEUP signal, which flips in level with the CAN communication signal. The GPIOPA0 pin of the STM32L431 detects this level change and triggers the chip to wake up from the sleep state and enter the working mode to respond to the CAN communication, completing the wake-up process.

[0037] R27 is a 10KΩ resistor connected between the output terminal of U10 and the power supply VCC3_3. Its main function is to act as a pull-up resistor. Through this function, R27 ensures that the MCU_WAKEUP signal can be correctly pulled high to a high level under certain conditions, thereby achieving stable output of the circuit and wake-up trigger of the microcontroller (such as STM32L431). When U10 does not actively pull down the output, R27 pulls the MCU_WAKEUP signal high to 3.3V through VCC3_3. If there is no R27, when U10 output is disconnected, the signal line may be in an uncertain state, leading to false triggering or instability. R27 eliminates this risk.

[0038] When the CAN0H signal indicates CAN communication activity (e.g., from high to low), the output state of U10 switches, and R27 cooperates with U10 to generate high-low level changes, ultimately triggering the STM32L431 to wake up from the sleep state through the MCU_WAKEUP signal. R27 ensures that the MCU_WAKEUP signal always remains high when U10 does not pull down, avoiding signal uncertainty and improving the reliability of the circuit.

[0039] The application discloses a wake-up method of an MCU wake-up circuit based on CAN communication, wherein a reference voltage is formed by dividing a power supply VCC through a voltage dividing module and is sent to an inverting input end of a comparator through a signal input module; a high level signal CAN0H of a CAN bus is sent to a forward input end of the comparator after being processed through the signal input module; the comparator compares the voltage between the forward input end and the inverting input end, outputs a first signal when the voltage of the forward input end is higher than that of the inverting input end, and outputs a second signal when the voltage of the forward input end is lower than that of the inverting input end; a GPIO pin of an MCU receives the first signal or the second signal output by the comparator and triggers to wake up from a sleep state and enter a working mode to respond to the CAN communication.

[0040] U10 is AP331AWG-7, which has low power consumption and high sensitivity and is suitable for the requirement of the circuit; the resistors are all patch resistors with an accuracy of 1%, so as to guarantee the accuracy of voltage division and current limiting, and the capacitors are 100nF ceramic capacitors, so as to realize efficient filtering. The modules are electrically connected through printed circuit board (PCB) wiring to form a complete CAN wake-up signal detection and conversion circuit, so as to guarantee that the signal transmission path is clear and stable.

[0041] As an implementation mode, before power-on, it is checked whether the circuit welding and device installation are correct; after power-on, the output level of the voltage dividing module and the signal at the input and output ends of U10 are measured by using an oscilloscope, and it is verified that the level change of the MCU_WAKEUP signal during the CAN communication meets the design expectation. Different rates and loads of the CAN communication scene are simulated, the stability of the wake-up function is tested, the circuit parameters (such as the resistance ratio of the voltage dividing resistors) are fine-tuned according to the test result, and the wake-up performance is optimized.

[0042] The wake-up circuit is integrated into a DTU system, cooperates with an STM32L431 master control chip and a CAN communication module, configures a GPIOPA0 pin of the STM32L431 as a wake-up detection mode, verifies the complete process of sleep-wake-up-response CAN communication of the system, ensures the compatibility with other functional modules of the DTU, and realizes low-power-consumption and high-reliability system operation.

[0043] The above merely describes preferred specific implementation modes of the application, but the protection scope of the application is not limited to this, any person skilled in the art can make equivalent replacement or change according to the technical scheme and the inventive concept of the application within the technical range disclosed by the application to obtain a technical scheme, concept and design, which should be covered in the protection scope of the application.

Claims

1. A MCU wake-up circuit based on CAN communication, characterized in that, The system includes a voltage divider module, a signal input module, and a circuit comparator module. The voltage divider module is connected to the inverting input terminal of the circuit comparator module via the signal input module. The CAN0H is connected to the non-inverting input terminal of the circuit comparator module via the signal input module. The circuit comparator module is connected to a power supply VCC. The output terminal of the circuit comparator module is connected to an MCU. When the voltage at the non-inverting input terminal is greater than that at the inverting input terminal, the circuit comparator module outputs a first signal. When the voltage at the non-inverting input terminal is less than that at the inverting input terminal, the circuit comparator module outputs a second signal.

2. The MCU wake-up circuit based on CAN communication according to claim 1, characterized in that, The voltage divider module includes resistors R29 and R31. One end of resistor R29 is connected to the power supply VCC, and the other end is connected to one end of resistor R31. The other end of resistor R31 is connected to GND. The circuit between resistors R29 and R31 is connected to the circuit comparison module.

3. The MCU wake-up circuit based on CAN communication according to claim 2, characterized in that, The signal input module includes resistors R25 and R15. The circuit between resistors R29 and R31 is connected to one end of resistor R25. The other end of resistor R25 is connected to the inverting input terminal of the circuit comparator module. One end of resistor R15 is connected to CAN0H, and the other end of resistor R15 is connected to the positive input terminal of the circuit comparator module.

4. A MCU wake-up circuit based on CAN communication according to any one of claims 1-3, characterized in that, The circuit comparison module includes a comparator U10, which has an inverting input terminal, a non-inverting input terminal, a power supply connection terminal, a ground terminal, and an output terminal. The circuit between the power supply connection terminal and the power supply VCC is connected to one end of a capacitor C26, and the other end of the capacitor C26 is connected to GND.

5. The MCU wake-up circuit based on CAN communication according to claim 4, characterized in that, The output of comparator U10 is connected to one end of resistor R27, and the other end of resistor R27 is connected to power supply VCC.

6. A MCU wake-up circuit based on CAN communication according to any one of claims 1-3 and 5, characterized in that, The wake-up circuit includes resistors R29, R31, R25, R15, R27, and capacitor C26, as well as comparator U10. The resistance of resistor R29 is 36KΩ, the resistance of resistor R31 is 10KΩ, the resistance of resistor R25 is 1KΩ, the resistance of resistor R15 is 1KΩ, the resistance of resistor R27 is 10KΩ, the capacitor C26 is 100nF, and the comparator U10 is an AP331AWG-7.

7. A wake-up method for an MCU wake-up circuit based on CAN communication, characterized in that: The voltage divider module divides the power supply VCC to form a reference voltage, which is then sent to the inverting input of the comparator via the signal input module. The high-level CAN0H signal of the CAN bus is processed by the signal input module and sent to the positive input terminal of the comparator. The comparator compares the voltage between the non-inverting input and the inverting input. When the voltage at the non-inverting input is higher than the voltage at the inverting input, the comparator outputs the first signal. When the voltage at the positive input terminal is lower than the voltage at the inverting input terminal, the comparator outputs a second signal; The MCU's GPIO pin receives the first or second signal output by the comparator and triggers a wake-up from sleep mode to enter working mode and respond to CAN communication.

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