CAN sleep wake-up circuit

Abstract

The utility model discloses a CAN (Controller Area Network) dormancy wake-up circuit, which comprises a CAN bus provided with N CAN loop nodes, and further comprises a data detection module used for detecting the use state of the CAN bus in real time in a low power consumption mode, generating a mode switching signal and transmitting the mode switching signal to an MCU (Microprogrammed Control Unit) module if the use state is a non-idle state, the use state comprises an idle state and a non-idle state; the CAN communication module is used for mutual communication among the CAN bus, the N CAN loop nodes and the MCU module; the MCU module is used for performing data interaction with the CAN core bus and the N CAN loop nodes through the CAN communication module; and the MCU module is also used for receiving the mode switching signal in the low-power-consumption mode, performing mode switching according to the mode switching signal, disconnecting the data detection module and entering a normal mode. When the CAN sleep wake-up circuit enters the normal mode, the data detection module is disconnected from the bus, and it is guaranteed that bus signals in the normal state are not attenuated.

Description

Technical Field

[0001] The utility model relates to the technical field of electrical control, in particular to a CAN sleep awakening circuit. Background Art

[0002] Low power consumption is particularly important for new energy and other battery-powered devices. In some industrial and automotive circuits, CAN communication is often used as a means of data exchange. When the bus is idle, the CAN communication circuit enters a low-power state to reduce energy loss. Currently, commonly used CAN low-power circuits use specialized CAN chips with sleep / wake-up functions. These chips have many pins and limited options. For example, patent application number CN202322278970 discloses a CAN wake-up circuit, in which the positive pole of the CAN bus is connected to one end of resistor R1, the other end of which is connected to port 1 of optocoupler U2, port 2 of optocoupler U2 is connected to resistor R2, the other end of which is connected to the negative pole of the CAN bus, port 4 of optocoupler U2 is connected to resistor R3, the other end of which is connected to the base of transistor Q1, the emitter of transistor Q1 is connected to the Vin input, the collector of transistor Q1 is connected to the Vout output, and resistor R4 is connected in parallel between the emitter and base of transistor Q1, and port 3 of optocoupler U2 is connected to the ground line. This circuit uses an optocoupler + transistor for data detection in CANH and CANL, but the circuit cannot disconnect the detection circuit in normal mode. Due to the influence of the internal diode of the optocoupler, in normal communication mode, the CANH current always flows to CANL. At the same time, the junction capacitance between CANH and CANL continues to increase. When there are too many external CAN signal nodes, the bus signal is attenuated due to the shunt and junction capacitance, resulting in abnormal communication and affecting system function. Utility Model Content

[0003] In order to solve the technical problems existing in the background technology, the utility model proposes a CAN sleep wake-up circuit.

[0004] The utility model proposes a CAN sleep wake-up circuit, which includes a CAN bus, wherein N CAN loop nodes are provided on the CAN bus, and further includes:

[0005] The data detection module is used to detect the usage status of the CAN bus in real time in low-power mode. If the usage status is non-idle, it generates a mode switching signal and transmits the mode switching signal to the MCU module. The usage status includes idle state and non-idle state;

[0006] CAN communication module, used for communication between the CAN bus, N CAN loop nodes and the MCU module;

[0007] MCU module, used to exchange data with the CAN core bus and N CAN loop nodes through the CAN communication module;

[0008] The MCU module is also used to receive a mode switching signal in the low power mode, and perform mode switching according to the mode switching signal, disconnect the data detection module, and enter the normal mode;

[0009] Among them, the MCU module and the CAN communication module are communicatively connected to each other, the output end of the MCU module is electrically connected to the input end of the data detection module, the input end of the MCU module is electrically connected to the output end of the data detection module, and the data detection module and the CAN communication module are electrically connected with a CAN bus.

[0010] Preferably, the CAN communication module specifically includes a CAN chip U2, a common-mode inductor L1, a TVS diode D1, a TSS semiconductor discharge tube D2, a TSS semiconductor discharge tube D3, a TSS semiconductor discharge tube D4, and a resistor R3; the CANH terminal of the CAN chip U2 is electrically connected to the first end of the common-mode inductor L1, the CANL terminal of the CAN chip U2 is electrically connected to the fourth end of the common-mode inductor L1, the second end of the common-mode inductor L1 is electrically connected to the CANH terminal of the CAN bus, the third end of the common-mode inductor L1 is electrically connected to the CANL terminal of the CAN bus, and the second end of the common-mode inductor L1 is electrically connected to the third end of the common-mode inductor L1. There is a resistor R3, the CANH end of the CAN bus is electrically connected to the first end of the TVS diode D1, the CANL end of the CAN bus is electrically connected to the second end of the TVS diode D1, the ground end of the TVS diode D1 is grounded, the CANH end of the CAN bus is electrically connected to one end of the TSS semiconductor discharge tube D3, the other end of the TSS semiconductor discharge tube D3 is grounded, a TSS semiconductor discharge tube D4 is electrically connected between the CANH end of the CAN bus and the CANL end of the CAN bus, the CANL end of the CAN bus is electrically connected to one end of the TSS semiconductor discharge tube D2, and the other end of the TSS semiconductor discharge tube D2 is grounded.

[0011] Preferably, the data detection module specifically includes an optocoupler U4, an optocoupler U5, a resistor R4, and a resistor R6. The positive input pole of the optocoupler U4 is electrically connected to one end of the resistor R6, and the other end of the resistor R6 is connected to the 3.3V power supply VDD. The negative input pole of the optocoupler U4 is grounded, the positive input pole of the optocoupler U4 is electrically connected to the output end of the MCU module, the output collector of the optocoupler U4 is electrically connected to the CANH end of the CAN communication module, the output emitter of the optocoupler U4 is electrically connected to the positive input pole of the optocoupler U5, the negative input pole of the optocoupler U5 is electrically connected to the CANL end of the CAN communication module, the output collector of the optocoupler U5 is electrically connected to one end of the resistor R4, the other end of the resistor R4 is connected to the 3.3V power supply VDD, and the output collector of the optocoupler U5 is electrically connected to the input end of the MCU module.

[0012] Preferably, it also includes:

[0013] Power supply module, used to supply power to the CAN communication module;

[0014] The MCU module is also used to control the power supply module to supply power to the CAN communication module. When the CAN bus is in an idle state, the MCU controls the power supply module to disconnect to achieve the low-power consumption function of CAN communication; the output end of the power supply module is electrically connected to the input end of the CAN communication module, and the input end of the power supply module is electrically connected to the output end of the MCU module.

[0015] Preferably, the power supply module specifically includes an optocoupler U3, a field-effect transistor Q1, a resistor R1, a resistor R2, and a resistor R5. The positive input electrode of the optocoupler U3 is connected to the 3.3V power supply VDD, the negative input electrode of the optocoupler U3 is electrically connected to one end of the resistor R1, the other end of the resistor R1 is electrically connected to the output end of the MCU module, the output collector of the optocoupler U3 is electrically connected to one end of the resistor R2, the other end of the resistor R2 is electrically connected to one end of the resistor R5, one end of the resistor R5 is electrically connected to the input end of the CAN communication module, one end of the resistor R5 is electrically connected to the drain of the field-effect transistor Q1, the other end of the resistor R5 is connected to the power supply VCC, and the other end of the resistor R5 is electrically connected to the source of the field-effect transistor Q1.

[0016] Preferably, the MCU module is specifically an MCU chip U1, and the MCU chip U1 is interconnected with the CAN communication module through the CAN-RX end and the CAN-TX end. The GPI01 end of the MCU chip U1 is electrically connected to the other end of the resistor R1, the GPI02 end of the MCU chip U1 is electrically connected to the output collector of the optocoupler U5, and the GPI03 end of the MCU chip U1 is electrically connected to the input positive pole of the optocoupler U4.

[0017] In the present invention, the proposed CAN sleep and wake-up circuit and data detection module are used to detect the usage status of the CAN bus in real time in low-power mode. If the usage status is non-idle, a mode switching signal is generated and transmitted to the MCU module. The usage status includes idle and non-idle states. The CAN communication module is used for mutual communication between the CAN bus, N CAN loop nodes, and the MCU module. The MCU module is used to exchange data with the CAN core bus and N CAN loop nodes through the CAN communication module. The MCU module is also used to receive the mode switching signal in low-power mode and switch modes according to the mode switching signal, disconnecting the data detection module and entering normal mode. This eliminates the need for a dedicated CAN sleep and wake-up chip, realizing the CAN wake-up and sleep function, with wide adaptability and high selectivity. The data detection module has no impact on the communication quality of the bus nodes in normal communication mode, and the corresponding number of nodes can be designed to be connected to the CAN bus according to actual application conditions. The data detection module is disconnected from the bus in normal mode, and there is no impact of shunting and increased junction capacitance, thereby ensuring that the bus signal is not attenuated in normal mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the module architecture of a CAN sleep wake-up circuit proposed in the utility model;

[0019] Figure 2 This is a structural diagram of an implementation scheme of a CAN sleep wake-up circuit proposed by the present invention;

[0020] Figure 3 This is a schematic diagram of the working process structure of a CAN sleep wake-up circuit proposed in the utility model.

[0021] Legend:

[0022] 1. MCU module; 2. CAN communication module; 3. Data detection module; 4. Power supply module. DETAILED DESCRIPTION

[0023] Reference Figure 1-3 The utility model proposes a CAN sleep wake-up circuit, including a CAN bus, N CAN loop nodes are provided on the CAN bus, and further includes:

[0024] The data detection module is used to detect the usage status of the CAN bus in real time in low-power mode. If the usage status is non-idle, it generates a mode switching signal and transmits the mode switching signal to the MCU module. The usage status includes idle state and non-idle state;

[0025] CAN communication module, used for communication between the CAN bus, N CAN loop nodes and the MCU module;

[0026] MCU module, used to exchange data with the CAN core bus and N CAN loop nodes through the CAN communication module;

[0027] The MCU module is also used to receive a mode switching signal in the low power mode, and perform mode switching according to the mode switching signal, disconnect the data detection module, and enter the normal mode;

[0028] Among them, the MCU module and the CAN communication module are communicatively connected to each other, the output end of the MCU module is electrically connected to the input end of the data detection module, the input end of the MCU module is electrically connected to the output end of the data detection module, and the data detection module and the CAN communication module are electrically connected with a CAN bus.

[0029] In this embodiment, the CAN communication module includes a CAN chip and a CAN protection circuit. The MCU exchanges data with node information via the CAN chip. When data exists on the bus (i.e., between CANH and CANL), the data detection module determines that the bus is working, and the MCU controls the power supply module to supply power to the CAN communication module. When the bus is idle (i.e., no data exists between CAN-H and CAN-L), the data detection module determines that the bus is idle, and the MCU controls the power supply module to disconnect, thus achieving low-power consumption for CAN communication.

[0030] In this embodiment, during the initial power-on stage, the MCU module first determines whether to enter low-power mode. When data is always present on the bus, the MCU module determines that it is not time to enter low-power mode and disconnects the data detection module. When the MCU module receives an external low-power instruction or the bus has been idle for a period of time, it will automatically disconnect the power supply module and enter low-power mode. In low-power mode, the data detection module detects in real time whether there is data on the bus. If no data exists, the system remains in low-power mode. If data exists, the MCU module switches modes, disconnects the data detection module, and enters normal mode. This process is all performed by the MCU module independently performing software logic judgment, with fast response speed and high timeliness.

[0031] Specifically, such as Figure 1 and Figure 2As shown, the CAN communication module specifically includes a CAN chip U2, a common-mode inductor L1, a TVS diode D1, a TSS semiconductor discharge tube D2, a TSS semiconductor discharge tube D3, a TSS semiconductor discharge tube D4, and a resistor R3; the CANH terminal of the CAN chip U2 is electrically connected to the first end of the common-mode inductor L1, the CANL terminal of the CAN chip U2 is electrically connected to the fourth end of the common-mode inductor L1, the second end of the common-mode inductor L1 is electrically connected to the CANH terminal of the CAN bus, the third end of the common-mode inductor L1 is electrically connected to the CANL terminal of the CAN bus, and the second end of the common-mode inductor L1 is electrically connected to the third end of the common-mode inductor L1. There is a resistor R3, the CANH end of the CAN bus is electrically connected to the first end of the TVS diode D1, the CANL end of the CAN bus is electrically connected to the second end of the TVS diode D1, the ground end of the TVS diode D1 is grounded, the CANH end of the CAN bus is electrically connected to one end of the TSS semiconductor discharge tube D3, the other end of the TSS semiconductor discharge tube D3 is grounded, a TSS semiconductor discharge tube D4 is electrically connected between the CANH end of the CAN bus and the CANL end of the CAN bus, the CANL end of the CAN bus is electrically connected to one end of the TSS semiconductor discharge tube D2, and the other end of the TSS semiconductor discharge tube D2 is grounded.

[0032] Specifically, such as Figure 1 and Figure 2 As shown, the data detection module specifically includes an optocoupler U4, an optocoupler U5, a resistor R4, and a resistor R6. The positive input electrode of the optocoupler U4 is electrically connected to one end of the resistor R6, and the other end of the resistor R6 is connected to the 3.3V power supply VDD. The negative input electrode of the optocoupler U4 is grounded, the positive input electrode of the optocoupler U4 is electrically connected to the output end of the MCU module, the output collector of the optocoupler U4 is electrically connected to the CANH end of the CAN communication module, the output emitter of the optocoupler U4 is electrically connected to the positive input electrode of the optocoupler U5, the negative input electrode of the optocoupler U5 is electrically connected to the CANL end of the CAN communication module, the output collector of the optocoupler U5 is electrically connected to one end of the resistor R4, the other end of the resistor R4 is connected to the 3.3V power supply VDD, and the output collector of the optocoupler U5 is electrically connected to the input end of the MCU module.

[0033] Specifically, such as Figure 1 and Figure 2 As shown, it also includes:

[0034] Power supply module, used to supply power to the CAN communication module;

[0035] The MCU module is also used to control the power supply module to supply power to the CAN communication module. When the CAN bus is in an idle state, the MCU controls the power supply module to disconnect to achieve the low-power consumption function of CAN communication; the output end of the power supply module is electrically connected to the input end of the CAN communication module, and the input end of the power supply module is electrically connected to the output end of the MCU module.

[0036] Specifically, such as Figure 1 and Figure 2 As shown, the power supply module specifically includes an optocoupler U3, a field effect transistor Q1, a resistor R1, a resistor R2, and a resistor R5. The positive input electrode of the optocoupler U3 is connected to the 3.3V power supply VDD, the negative input electrode of the optocoupler U3 is electrically connected to one end of the resistor R1, the other end of the resistor R1 is electrically connected to the output end of the MCU module, the output collector of the optocoupler U3 is electrically connected to one end of the resistor R2, the other end of the resistor R2 is electrically connected to one end of the resistor R5, one end of the resistor R5 is electrically connected to the input end of the CAN communication module, one end of the resistor R5 is electrically connected to the drain of the field effect transistor Q1, the other end of the resistor R5 is connected to the power supply VCC, and the other end of the resistor R5 is electrically connected to the source of the field effect transistor Q1.

[0037] Specifically, such as Figure 1 and Figure 2 As shown, the MCU module is specifically the MCU chip U1. The MCU chip U1 is connected to the CAN communication module through the CAN-RX terminal and the CAN-TX terminal. The GPI01 terminal of the MCU chip U1 is electrically connected to the other end of the resistor R1. The GPI02 terminal of the MCU chip U1 is electrically connected to the output collector of the optocoupler U5. The GPI03 terminal of the MCU chip U1 is electrically connected to the input positive pole of the optocoupler U4.

[0038] In this embodiment, if Figure 2 As shown, MCU chip U1 exchanges data with the CAN chip via its built-in CAN transceiver pins. It also autonomously determines and configures the CTR1 output level based on the INT and WAKEUP signal states, thereby controlling the CAN communication chip's switching between low-power and normal modes. After initial power-up, the MCU performs a power-on self-test on the CAN bus using CAN-RX, CAN-TX, and CAN bus signals. At this point, the MCU configures the INT signal to output a low level, disconnecting the data detection circuit. If there is no data on the MCU's CAN-RX and CAN-TX pins, and this state persists for a period of time, or if a specific instruction to enter a low-power state is received, CTR1 is configured by the MCU to output a high level, turning off the optocoupler U3 and the P-MOS transistor. This disconnects the power supply to U2, and the CAN enters a low-power state.

[0039] In the low-power state, CTR1 is configured by the MCU to output a high level, the optocoupler U3 is not conducting, INT is configured by the MCU to output a high level, the optocoupler U4 is conducting, and WAKEUP is configured as an input mode. When there is no data on the bus, that is, there is no voltage difference between CANH and CANL, U4 is in the on state, U5 does not meet the conduction condition, WAKEUP is high, and the MCU determines that it maintains a low-power state at this time; when there is data on the bus, that is, there is a voltage difference between CANH and CANL (generally around 2.5V), U4 is in the on state, U5 meets the conduction condition, WAKEUP is a level flip to a low level, and the MCU determines that it needs to switch to a normal state. CTR1 is configured by the MCU to output a low level, U3 is turned on and then Q1 is turned on, U2 is powered normally, and CAN enters a normal working mode.

[0040] In the circuit, R3 is a 120Ω CAN terminal resistor, and L1 is a common-mode inductor, used to filter out common-mode electromagnetic interference from the CANH and CANL signal lines, attenuate the high-frequency portion of the differential signal, suppress electromagnetic interference emanating from the CAN interface itself, and improve the circuit's conducted interference. D1 is a CAN ESD-specific TVS, used for anti-static protection on the signal lines. D2, D3, and D4 are TSS, used to suppress differential-mode and industrial-mode surge interference and enhance the bus's anti-interference capabilities. In this circuit, U2 is a conventional CAN chip, requiring only conventional transceiver, CANH and CANL, and power pins. There's no need to use a chip with CAN wake-up / sleep functionality. The circuit is compatible with both isolated and non-isolated chips, and is compatible with all commercially available CAN chips, offering a wide range of options and competitive pricing.

[0041] In this embodiment, in normal working mode, CTR1 is configured by the MCU to output a low level, the optocoupler U3 is turned on, INT is configured by the MCU to output a low level, the optocoupler U4 is not turned on, the WAKEUP signal is not detected, and the data detection module is disconnected from the bus. There is no influence of shunting and increase in junction capacitance, thereby ensuring that the bus signal is not attenuated under normal conditions.

[0042] The above is only a preferred specific implementation method of the present invention, but the protection scope of the present invention is not limited to this. Any technician familiar with the technical field within the technical scope disclosed by the present invention can make equivalent replacements or changes based on the technical solution and utility model concept of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A CAN sleep wake-up circuit, comprising a CAN bus, wherein the CAN bus is provided with N CAN loop nodes, characterized in that: Also includes: The data detection module is used to detect the usage status of the CAN bus in real time in low-power mode. If the usage status is non-idle, it generates a mode switching signal and transmits the mode switching signal to the MCU module. The usage status includes idle state and non-idle state; CAN communication module, used for communication between the CAN bus, N CAN loop nodes and the MCU module; MCU module, used to exchange data with the CAN core bus and N CAN loop nodes through the CAN communication module; The MCU module is also used to receive a mode switching signal in the low power mode, and perform mode switching according to the mode switching signal, disconnect the data detection module, and enter the normal mode; Among them, the MCU module and the CAN communication module are communicatively connected to each other, the output end of the MCU module is electrically connected to the input end of the data detection module, the input end of the MCU module is electrically connected to the output end of the data detection module, and the data detection module and the CAN communication module are electrically connected with a CAN bus.

2. The CAN sleep wake-up circuit according to claim 1, characterized in that: The CAN communication module specifically includes a CAN chip U2, a common-mode inductor L1, a TVS diode D1, a TSS semiconductor discharge tube D2, a TSS semiconductor discharge tube D3, a TSS semiconductor discharge tube D4, and a resistor R3; the CANH end of the CAN chip U2 is electrically connected to the first end of the common-mode inductor L1, the CANL end of the CAN chip U2 is electrically connected to the fourth end of the common-mode inductor L1, the second end of the common-mode inductor L1 is electrically connected to the CANH end of the CAN bus, the third end of the common-mode inductor L1 is electrically connected to the CANL end of the CAN bus, and the second end of the common-mode inductor L1 is electrically connected to the third end of the common-mode inductor L1. Resistor R3, the CANH end of the CAN bus is electrically connected to the first end of the TVS diode D1, the CANL end of the CAN bus is electrically connected to the second end of the TVS diode D1, the ground end of the TVS diode D1 is grounded, the CANH end of the CAN bus is electrically connected to one end of a TSS semiconductor discharge tube D3, the other end of the TSS semiconductor discharge tube D3 is grounded, a TSS semiconductor discharge tube D4 is electrically connected between the CANH end of the CAN bus and the CANL end of the CAN bus, the CANL end of the CAN bus is electrically connected to one end of a TSS semiconductor discharge tube D2, and the other end of the TSS semiconductor discharge tube D2 is grounded.

3. The CAN sleep wake-up circuit according to claim 1, characterized in that: The data detection module specifically includes an optocoupler U4, an optocoupler U5, a resistor R4, and a resistor R6. The positive input pole of the optocoupler U4 is electrically connected to one end of the resistor R6, and the other end of the resistor R6 is connected to the 3.3V power supply VDD. The negative input pole of the optocoupler U4 is grounded, the positive input pole of the optocoupler U4 is electrically connected to the output end of the MCU module, the output collector of the optocoupler U4 is electrically connected to the CANH end of the CAN communication module, the output emitter of the optocoupler U4 is electrically connected to the positive input pole of the optocoupler U5, the negative input pole of the optocoupler U5 is electrically connected to the CANL end of the CAN communication module, the output collector of the optocoupler U5 is electrically connected to one end of the resistor R4, the other end of the resistor R4 is connected to the 3.3V power supply VDD, and the output collector of the optocoupler U5 is electrically connected to the input end of the MCU module.

4. The CAN sleep wake-up circuit according to claim 3, characterized in that: Also includes: Power supply module, used to supply power to the CAN communication module; The MCU module is also used to control the power supply module to supply power to the CAN communication module. When the CAN bus is in an idle state, the MCU controls the power supply module to disconnect to achieve the low-power consumption function of CAN communication; the output end of the power supply module is electrically connected to the input end of the CAN communication module, and the input end of the power supply module is electrically connected to the output end of the MCU module.

5. The CAN sleep wake-up circuit according to claim 4, characterized in that: The power supply module specifically includes an optocoupler U3, a field-effect transistor Q1, a resistor R1, a resistor R2, and a resistor R5. The positive input of the optocoupler U3 is connected to the 3.3V power supply VDD, the negative input of the optocoupler U3 is electrically connected to one end of the resistor R1, and the other end of the resistor R1 is electrically connected to the output end of the MCU module. The output collector of the optocoupler U3 is electrically connected to one end of the resistor R2, and the other end of the resistor R2 is electrically connected to one end of the resistor R5. One end of the resistor R5 is electrically connected to the input end of the CAN communication module, one end of the resistor R5 is electrically connected to the drain of the field-effect transistor Q1, the other end of the resistor R5 is connected to the power supply VCC, and the other end of the resistor R5 is electrically connected to the source of the field-effect transistor Q1.

6. The CAN sleep wake-up circuit according to claim 5, characterized in that: The MCU module is specifically the MCU chip U1. The MCU chip U1 is connected to the CAN communication module through the CAN-RX terminal and the CAN-TX terminal. The GPI01 terminal of the MCU chip U1 is electrically connected to the other end of the resistor R1. The GPI02 terminal of the MCU chip U1 is electrically connected to the output collector of the optocoupler U5. The GPI03 terminal of the MCU chip U1 is electrically connected to the input positive pole of the optocoupler U4.

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