CN112965412B - MCU unit resetting method and system and CAN anti-interference communication device - Google Patents
MCU unit resetting method and system and CAN anti-interference communication device Download PDFInfo
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- CN112965412B CN112965412B CN202110146290.0A CN202110146290A CN112965412B CN 112965412 B CN112965412 B CN 112965412B CN 202110146290 A CN202110146290 A CN 202110146290A CN 112965412 B CN112965412 B CN 112965412B
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/04—Programme control other than numerical control, i.e. in sequence controllers or logic controllers
- G05B19/042—Programme control other than numerical control, i.e. in sequence controllers or logic controllers using digital processors
- G05B19/0423—Input/output
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B2219/00—Program-control systems
- G05B2219/20—Pc systems
- G05B2219/25—Pc structure of the system
- G05B2219/25257—Microcontroller
Abstract
The invention relates to the technical field of MCU (microprogrammed control Unit) resetting, and discloses a method and a system for resetting an MCU and a CAN anti-interference communication device. The MCU reset method is suitable for an MCU reset system, and the MCU reset system comprises a watchdog unit, a voltage conversion unit and an MCU unit; the watchdog unit is connected with the MCU unit through a WDI pin, the output end of the voltage conversion unit is connected with the power input end of the MCU unit, and the reset output pin of the watchdog unit is connected with the power enable pin of the voltage conversion unit. Has the advantages that: the reset method of the invention can realize automatic power-off and automatic power-on of the MCU unit, and avoid the trouble of considering power-on and power-off. The CAN anti-interference communication device applies the reset system and is additionally provided with the isolation pulse transformer and the bias resistor, so that the CAN transceiver CAN be further protected, and the damage of the CAN transceiver is avoided.
Description
Technical Field
The invention relates to the technical field of MCU (microprogrammed control Unit) resetting, in particular to a method and a system for resetting an MCU and a CAN anti-interference communication device.
Background
At present, the problem that the CAN bus of the electric automobile is subjected to electromagnetic interference becomes more complicated because the electromagnetic environment of the automobile is greatly changed. The electromagnetic interference suffered by the automobile CAN bus communication mainly comes from common mode interference and differential mode interference generated by an automobile internal circuit or an external power frequency magnetic field. During the working process of the power system of the electric automobile, for example, the battery discharges and is subjected to DC-AC conversion, voltage is output to the motor driver, and the motor drives the vehicle to move forward and can drive the air conditioner compressor to refrigerate. When the electric vehicle is downhill, the motor drive energy recovery system feeds back to the battery for charging through AC-DC conversion. These voltage variations are converted by the inverter. During the conversion process, the switching devices IGBT and power diode of the motor controller and inverter generate high-frequency electromagnetic interference, and these strong electromagnetic interferences are coupled to the transmission line of the CAN bus nearby by magnetic field radiation, as shown in fig. 1, resulting in common-mode and differential-mode pulse interference of the CAN bus.
Because the CAN bus has wide application, the above discussion only uses the car CAN bus communication as an example, and those skilled in the art CAN apply the technical scheme disclosed in the present application to other application fields with strong interference, such as new energy electric cars, and CAN be extended to be applied to the fields of servo drive robots, light rail trains, medical equipment, and the like.
At present, the mode of increasing signal isolation and power isolation between CAN controller and the CAN transceiver is adopted to traditional CAN bus anti-interference design conventionality, and the direct current coupling of CAN bus is isolated outside, reduces external interference to master control circuit's influence, increases the watchdog chip simultaneously and monitors MCU, in case MCU is died by the interference of external cluster-in, then CAN reset to MCU's procedure through the pin that resets. As shown in fig. 2 and 3.
When the CAN bus is interfered by strong electromagnetic pulse, the electromagnetic interference pulse exceeds the EMC (battery compatibility) tolerance of the MCU (vehicle-mounted microprocessor), the pulse has a small probability of causing a large amount of charges to be concentrated at the MCU, and the charges cause the MCU to be electrically halted due to no bleed-off path (electric vehicle equipment is generally designed to meet the isolation withstand voltage requirement in a floating manner).
However, the watchdog circuit in the prior art cannot eliminate the dead halt state by resetting the MCU, and the whole circuit must be powered up again to recover the normal operation of the MCU. This causes inconvenience in manually powering off and on.
Therefore, an MCU reset method is needed to solve the problem that the MCU needs to be manually powered off and on after it crashes.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: and the MCU needs to be powered off and on manually after the halt.
In order to achieve the above object, the present invention provides a MCU reset method, which is suitable for an MCU reset system including a watchdog unit, a voltage conversion unit, and an MCU unit.
The MCU unit resetting method comprises the following steps:
after the power is supplied to the watchdog unit, a first control signal is sent to the voltage conversion unit after first time delay, so that the voltage conversion unit sends and outputs a first voltage to the MCU unit according to the first control signal, the MCU unit enters a normal working state, and a dog feeding signal is fed back to the watchdog unit; the MCU unit can continuously feed back a dog feeding signal to the watchdog unit when entering a normal working state, and the MCU unit stops feeding back the dog feeding signal to the watchdog unit when entering an abnormal working state.
The watchdog unit sends a first control signal to control the voltage conversion unit to output a first voltage to the MCU unit in a working state of receiving the dog feeding signal of the MCU unit.
When the watchdog unit does not receive the feedback dog feeding signal of the MCU unit, the watchdog unit sends a second control signal to the voltage conversion unit after a second delay, so that the voltage conversion unit sends zero-volt voltage to the MCU unit according to the second control signal, and the MCU unit stops working; and after the watchdog unit sends a second control signal and third delay, the watchdog unit sends the first control signal to the voltage conversion unit again, so that the voltage conversion unit outputs the first voltage to the MCU unit again, and the MCU unit enters a normal working state again.
Furthermore, a CAN controller is arranged in the MCU unit and used for sending self state information to the MCU unit; and the MCU unit is also used for stopping feeding the dog feeding signal back to the watchdog unit when the self state information of the CAN controller is abnormal working state information.
The application also discloses an MCU resetting system, which is used for the MCU resetting method; the MCU reset system comprises a watchdog unit, a voltage conversion unit and an MCU unit.
The watchdog unit is connected with the MCU unit through a WDI pin, the output end of the voltage conversion unit is connected with the power input end of the MCU unit, and the reset output pin of the watchdog unit is connected with the power enable pin of the voltage conversion unit.
Furthermore, a CAN controller is arranged in the MCU unit of the reset system, and the output end of the voltage conversion unit is connected with the power input end of the CAN controller.
Furthermore, the watchdog unit is provided with an MR pin, and a jumper cap is installed on the MR pin.
Furthermore, the watchdog unit and the voltage conversion unit are directly powered by a power supply, the watchdog unit is a watchdog chip, the voltage conversion unit is a power supply chip, and the MCU unit is a microprocessor MCU.
The application also discloses a CAN bus anti jamming unit, the device MCU reset system, still include the CAN transceiver, the CAN transceiver with CAN controller both way junction.
Furthermore, the anti-jamming device further comprises an isolation pulse transformer, the isolation pulse transformer is connected with the CAN transceiver in a two-way mode through a connecting line, a bias resistor is installed on the connecting line, and the bias resistor is used for adjusting voltage during signal transmission to enable normal CAN signals to pass through the isolation pulse transformer.
Further, the CAN transceiver is connected with the CAN controller in two directions, specifically: the CAN controller is in bidirectional connection with the CAN transceiver through a signal isolation device.
Furthermore, a voltage isolation device is connected in parallel to the signal isolation device.
Compared with the prior art, the MCU resetting method, the MCU resetting system and the CAN anti-interference communication system have the advantages that:
1. by adopting the MCU resetting method, when the MCU enters an abnormal working state, the watchdog unit loses a dog feeding signal fed back by the MCU, the watchdog unit controls the voltage conversion unit to output zero-volt voltage, and the power supply of the MCU is cut off; after a period of time after power failure, the watchdog unit sends a control signal to the voltage conversion unit, so that the voltage conversion unit outputs the working voltage of the MCU unit, and the MCU unit is powered on again. The process is automatically completed, so that the trouble of power on and power off caused by manpower is avoided.
2. In the MCU resetting system, the WDI pin of the watchdog unit is connected with the MCU unit, the output end of the voltage conversion unit is connected with the power input end of the MCU unit, the reset output pin of the watchdog unit is connected with the power enable pin of the voltage conversion unit, an interlocking structure of the watchdog unit and the voltage conversion unit is formed, and particularly, when the MCU unit is halted, the MCU unit losing the 'dog feeding' action CAN actively cut off the enable pin of the voltage conversion unit through the watchdog unit, so that the MCU unit and the CAN controller are powered off, and then the MCU unit and the CAN controller are powered on after time delay, so that inconvenience caused by manual power-off and power-on actions is avoided. The circuit for directly resetting the reset pin of the MCU by the watchdog unit is changed, the MCU unit can be recovered to work after being electrified again after the MCU unit is interfered and halted by adopting a mode that the watchdog unit controls the voltage conversion unit, and the problem that the reset pin of the MCU unit fails under strong interference is avoided.
3. In the MCU resetting system, the jumper cap is added on the MR pin of the watchdog unit, so that the power-on function of the MCU resetting system can be turned off when a user downloads a program of the MCU unit.
4. The CAN bus anti-interference device is additionally provided with the pulse transformer which directly isolates CAN signals, so that the CAN transceiver CAN be electrically isolated and protected, and the CAN transceiver is prevented from being damaged due to potential difference or surge pulse on the bus.
5. The offset resistor is added on the basis of adding the isolation pulse transformer in the CAN bus anti-jamming device, so that the tolerance threshold of a recessive level is improved, the CAN node is not easily influenced by accidental interference pulses to cause error interruption in a receiving state, and useless response of a system is reduced.
Drawings
FIG. 1 is a schematic diagram of a transmission line in the background of the invention in which electromagnetic interference is coupled to a CAN bus in its vicinity by magnetic field radiation;
FIG. 2 is a schematic diagram of power isolation and signal isolation in the background of the invention;
FIG. 3 is a schematic diagram illustrating the reset of the MCU by the watchdog chip in the background art of the present invention;
FIG. 4 is a schematic diagram of the MCU unit reset of the present invention;
FIG. 5 is an embodiment of an MCU unit of the present invention;
FIG. 6 is a schematic circuit diagram of the MCU unit reset of the present invention;
FIG. 7 is a circuit schematic of the connection of the isolation pulse transformer and CAN transceiver of the present invention;
FIG. 8 is a voltage signal range of the CAN bus with the isolation pulse transformer added without the bias resistor;
FIG. 9 shows the level change of the CAN bus with the addition of the isolation pulse transformer and the bias resistor module.
Detailed Description
The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
Example 1:
the invention provides an MCU reset method, which comprises the following steps:
as will be appreciated with reference to fig. 4, the method is applicable to an MCU reset system including a watchdog unit, a voltage conversion unit, and an MCU unit;
the MCU unit resetting method comprises the following steps:
after the power is supplied to the watchdog unit, a first control signal is sent to the voltage conversion unit after first time delay, so that the voltage conversion unit sends and outputs a first voltage to the MCU unit according to the first control signal, the MCU unit enters a normal working state, and a dog feeding signal is fed back to the watchdog unit; the MCU unit can continuously feed back a dog feeding signal to the watchdog unit when entering a normal working state, and the MCU unit stops feeding back the dog feeding signal to the watchdog unit when entering an abnormal working state.
The watchdog unit sends a first control signal to control the voltage conversion unit to output a first voltage to the MCU unit in a working state of receiving the dog feeding signal of the MCU unit.
And the watchdog unit which loses the feedback dog feeding signal of the MCU unit sends a second control signal to the voltage conversion unit after second time delay, so that the voltage conversion unit sends zero-volt voltage to the MCU unit according to the second control signal, and the MCU unit stops working.
And after the watchdog unit sends a second control signal and third delay, the watchdog unit sends the first control signal to the voltage conversion unit again, so that the voltage conversion unit outputs the first voltage to the MCU unit again, and the MCU unit enters a normal working state again.
Furthermore, a CAN controller is arranged in the MCU unit in the reset method, and the CAN controller is used for sending self state information to the MCU unit; and the MCU unit is also used for stopping feeding the dog feeding signal back to the watchdog unit when the self state information of the CAN controller is abnormal working state information.
Example 2:
the invention discloses an MCU (microprogrammed control Unit) resetting system, which applies the resetting method in embodiment 1.
The MCU reset system comprises a watchdog unit, a voltage conversion unit and an MCU unit; the watchdog unit is connected with the MCU unit through a WDI pin, the output end of the voltage conversion unit is connected with the power input end of the MCU unit, and the reset output pin of the watchdog unit is connected with the power enable pin of the voltage conversion unit.
The MCU unit of the reset system is internally provided with a CAN controller, and the output end of the voltage conversion unit is connected with the power input end of the CAN controller.
The watchdog unit is provided with an MR pin, and a jumper cap is installed on the MR pin.
When the user is downloading the MCU program, the MCU will need to turn off this re-power-on function in order to avoid the user downloading being affected by re-power-on without watchdog action, so the jumper cap of J5 is added to the MR pin of watchdog unit CAT706 SVI. After the jumper cap is plugged in, the watchdog unit CAT706SVI cannot output a low level to the EN pin of the CATs 6219-330, and the MCU cannot be powered up again.
The watchdog unit and the voltage conversion unit are directly powered by a power supply, the watchdog unit is a watchdog chip, the voltage conversion unit is a power supply chip, and the MCU unit is a microprocessor MCU.
The specifically adopted product types are as follows: the watchdog chip U7 is a watchdog voltage monitoring chip CAT706SVI, and the power supply chip U5 is a 5V to 3.3V power supply chip CAT 6219-330. The MCU unit is a microprocessor MCU. The three chips form a control loop circuit to ensure that the MCU can automatically recover to be electrified again under the condition of crash. The MCU maintains the 3.3V normal output of CAT706SVI to CAT 6219-330 through WDI pin feeding dog, and the normal output of voltage 3.3V maintains the normal work of the MCU. Once the MCU crashes and the MCU dog feeding action stops, the CAT706SVI performs reset enabling action on the CATs 6219-330, thereby generating action of powering up the MCU again.
In order to avoid voltage fluctuation of a power supply, a TVS tube, a first capacitor and a second capacitor are connected to the input end of the voltage conversion unit, and a third capacitor and a fourth capacitor are connected to the output end of the voltage conversion unit in order to eliminate low-frequency electromagnetic interference.
The method specifically comprises the following steps: the TVS tube of D33SMBJ5.0CA and the filter capacitors of C46 and C11 are added into the input pole of the VCC5V power supply (namely, the input end of the voltage conversion unit) to prevent the voltage fluctuation of the VCC5V power supply, and the capacitors of C47 and EP2 are connected into the output pole of 3.3V (namely, the output end of the voltage conversion unit) to eliminate low-frequency electromagnetic interference.
The operation of the reset system of the present invention is described with reference to fig. 5:
1. after the power is on, the watchdog chip is powered on, and after 200ms delay, the 5V to 3.3V power supply chip outputs logic 1 enable, so that the power supply chip can output 3.3V;
2, the MCU processor and the CAN controller start to work normally after 3.3V, and simultaneously, the program feeds a watchdog chip with a program to enable the watchdog chip to maintain the enabling of a 5V to 3.3V power supply chip;
3. once the MCU microprocessing or the CAN controller is interfered to crash, the microprocessor stops the watchdog feeding action, after the timeout is 1.6 seconds, the watchdog chip reverses the watchdog reset output pin to be logic 0, namely, the 5V to 3.3V power supply chip is forbidden, so that the 3.3V output is stopped, and the MCU and the CAN controller of the microprocessor are completely powered down. Then, after 200ms, the power-on process is repeated from the process 1.
Example 3:
the invention also discloses a CAN bus anti-interference device, which comprises the MCU reset system and a CAN transceiver, wherein the CAN transceiver is bidirectionally connected with the CAN controller.
The conventional CAN bus anti-jamming circuit only protects the CAN controller, and the CAN transceiver is abandoned outside the isolation and still damaged by jamming pulses. In order to protect the CAN transceiver, an isolation pulse transformer is connected to the side of the CAN transceiver close to the CAN bus of the electric automobile when the CAN bus anti-interference hardware circuit is designed. Since the arbitration function will affect the peripheral addition of the pulse isolation transformer, in order to improve the anti-interference capability, it is necessary to abandon this function. The elimination of arbitration function and the addition of isolation pulse transformer is compatible with the design of improved intelligent retransmission and error recovery software program. Meanwhile, the two technical means CAN better improve the anti-interference capability of the CAN bus.
Referring to fig. 7, the anti-jamming device further includes an isolation pulse transformer, and the CAN transceiver and the isolation pulse transformer are connected in a bidirectional manner through a connection line.
The circuit directly isolates CAN bus signals through the isolation pulse transformer, removes a direct current coupling channel, improves common mode voltage resistance, and achieves the purpose of protecting a CAN transceiver and a CAN controller. The isolation pulse transformer adopts an isolation transformer of an MVB bus similar to the CAN bus so as to meet the requirement of the CAN bus on the highest transmission rate of 1Mbps baud rate.
The technical scheme disclosed in the application provides an isolation pulse transformer, and the specific model is T60430. A person skilled in the art can select a proper isolation pulse transformer according to needs to realize the direct isolation of the signals, remove a direct current coupling channel and improve the common-mode voltage resistance.
In order to solve the problem that the isolation pulse transformer obstructs normal signal transmission, a bias resistor is installed on the connecting line. The bias resistor is used for adjusting the voltage during signal transmission so that normal CAN signals CAN pass through the isolation pulse transformer.
As shown in FIG. 8, the voltage variation range of CANH and CANL is changed due to the addition of the isolation pulse transformer, the voltage variation range of CANH is 2.5V-3.5V, and the voltage variation range of CANL is 2.5V-1.5V. The difference level after CANH-CANL superposition is 0-2V. When the differential signal is subjected to electromagnetic interference, although electromagnetic isolation CAN be realized through the isolation pulse transformer, the normal CAN signal is also isolated and cannot be transmitted.
In order to enable the CAN signal after the interference is isolated to pass through the isolation pulse transformer, a bias resistance circuit needs to be added in the isolation circuit. The CAN transceiver is connected with the isolation pulse transformer through a connecting wire, and a bias resistor is installed on the connecting wire.
As CAN be seen from fig. 7, the CANH interface of the CAN transceiver is connected to the positive input pin of the isolation pulse transformer, and the CANL interface of the CAN transceiver is connected to the negative input pin of the isolation pulse transformer. In the prior art, the isolation pulse transformer has a plurality of models, but in order to realize the function of the application, the CAN transceiver should be connected with a pin of the isolation pulse transformer, which has a corresponding transmission function.
Further, the CAN transceiver U1 used in this application has a model of PCA82C251, the isolation pulse transformer has a model of T60430, CANH of the CAN transceiver is connected to 3 pins (+ pole) of the source of the isolation transformer, CANL is connected to 8 pins (-pole) of the source of the isolation transformer.
Further, the technical scheme of the application is disclosed in detail, a pull-down bias resistor to GND is installed on a connecting line of a CANH interface of the CAN transceiver and an input positive terminal pin of an isolation pulse transformer, and a pull-up bias resistor to a power supply is installed on a connecting line of a CANL interface of the CAN transceiver and an input negative terminal pin of the isolation pulse transformer.
Furthermore, in the technical solution of the present application, a "pull-down bias resistor" of 390 Ω to GND ground is added to the CANH signal line, and a "pull-up bias resistor" of 390 Ω to VCC5V power supply is added to the CANL signal line.
Referring to the attached figure 9, the circuit obtained through experimental results CAN bias the normal 0-2V differential level of the CAN bus signal to a negative level to about-1V, and finally CAN normally receive and transmit the CAN signal through the isolation transformer. All CAN chips are protected by means of the 2500VDC direct current isolation withstand voltage of the isolation transformer. And because this design has adopted the offset resistance module, the static differential recessive level reduces to-1V from 0V, the threshold value according to the logic change of differential level in international standard ISO 11898-1 of CAN bus is the standard of 0.5V, the anti-interference tolerance of recessive level rises to 1.5V from 0.5V too, thus make the interference killing feature of the node strengthened too (CAN transceiver does not have the driving capability in the recessive time, is disturbed very easily).
The anti-interference purpose can be realized by selecting a proper bias resistor through calculation according to an actual circuit by a person skilled in the art.
Example 4:
in order to further improve the anti-interference capability of the CAN anti-interference device, a signal isolation device and a power isolation device are arranged between the CAN transceiver and the CAN controller.
CAN transceiver and CAN controller both way junction specifically are: the CAN controller is in bidirectional connection with the CAN transceiver through a signal isolation device.
And the signal isolation device is connected with a voltage isolation device in parallel.
Referring to fig. 2 and 7, a signal isolation device is connected between the CAN controller and the CAN transceiver, the signal isolation device is connected with the CAN controller in a bidirectional manner, and the CAN transceiver is connected with the signal isolation device in a bidirectional manner.
And a power supply isolation device is also connected between the CAN controller and the CAN transceiver and is a ZY0505 BS-1W circuit.
The signal isolation device is a 6N137 photoelectric isolation chip or a capacitance isolation chip ISO 7221.
Furthermore, the latest capacitive isolation chip ISO7221 is adopted for signal isolation in the technical scheme disclosed by the application, and compared with a conventional 6N137 photoelectric isolation chip, the photoelectric isolation chip has a smaller volume, the transmission speed is 10 times higher than that of the photoelectric isolation chip, and the loss of the photoelectric isolation chip to the transmission signal edge can be reduced.
To sum up, the embodiment of the invention provides a method and a system for resetting an MCU unit and a CAN anti-interference communication device, and the beneficial effects are as follows:
1. by adopting the MCU resetting method, when the MCU enters an abnormal working state, the watchdog unit loses a dog feeding signal fed back by the MCU, the watchdog unit controls the voltage conversion unit to output zero-volt voltage, and the power supply of the MCU is cut off; after a period of time after power failure, the watchdog unit sends a control signal to the voltage conversion unit, so that the voltage conversion unit outputs the working voltage of the MCU unit, and the MCU unit is powered on again. The process is automatically completed, so that the trouble of power on and power off caused by manpower is avoided. 2. In the MCU resetting system, the WDI pin of the watchdog unit is connected with the MCU unit, the output end of the voltage conversion unit is connected with the power input end of the MCU unit, the reset output pin of the watchdog unit is connected with the power enable pin of the voltage conversion unit, an interlocking structure of the watchdog unit and the voltage conversion unit is formed, and particularly, when the MCU unit is halted, the MCU unit losing the 'dog feeding' action CAN actively cut off the enable pin of the voltage conversion unit through the watchdog unit, so that the MCU unit and the CAN controller are powered off, and then the MCU unit and the CAN controller are powered on after time delay, so that inconvenience caused by manual power-off and power-on actions is avoided. The circuit for directly resetting the reset pin of the MCU by the watchdog unit is changed, the MCU unit can be recovered to work after being electrified again after the MCU unit is interfered and halted by adopting a mode that the watchdog unit controls the voltage conversion unit, and the problem that the reset pin of the MCU unit fails under strong interference is avoided.
3. In the MCU resetting system, the jumper cap is added on the MR pin of the watchdog unit, so that the power-on function of the MCU resetting system can be turned off when a user downloads a program of the MCU unit.
4. The CAN bus anti-interference device is additionally provided with the pulse transformer which directly isolates CAN signals, so that the CAN transceiver CAN be electrically isolated and protected, and the CAN transceiver is prevented from being damaged due to potential difference or surge pulse on the bus.
5. The offset resistor is added on the basis of adding the isolation pulse transformer in the CAN bus anti-jamming device, so that the tolerance threshold of a recessive level is improved, the CAN node is not easily influenced by accidental interference pulses to cause error interruption in a receiving state, and useless response of a system is reduced.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and substitutions can be made without departing from the technical principle of the present invention, and these modifications and substitutions should also be regarded as the protection scope of the present invention.
Claims (10)
1. The MCU reset method is characterized by being suitable for an MCU reset system, wherein the MCU reset system comprises a watchdog unit, a voltage conversion unit and an MCU unit;
the MCU unit resetting method comprises the following steps:
after the power is supplied to the watchdog unit, a first control signal is sent to the voltage conversion unit after first time delay, so that the voltage conversion unit sends and outputs a first voltage to the MCU unit according to the first control signal, the MCU unit enters a normal working state, and a dog feeding signal is fed back to the watchdog unit; the MCU unit can continuously feed back a dog feeding signal to the watchdog unit when entering a normal working state, and stops feeding back the dog feeding signal to the watchdog unit when entering an abnormal working state;
the watchdog unit sends a first control signal to control the voltage conversion unit to output a first voltage to the MCU unit in a working state of receiving a dog feeding signal of the MCU unit;
when the watchdog unit does not receive the feedback dog feeding signal of the MCU unit, the watchdog unit sends a second control signal to the voltage conversion unit after a second delay, so that the voltage conversion unit sends zero-volt voltage to the MCU unit according to the second control signal, and the MCU unit stops working;
and after the watchdog unit sends a second control signal and third delay, the watchdog unit sends the first control signal to the voltage conversion unit again, so that the voltage conversion unit outputs the first voltage to the MCU unit again, and the MCU unit enters a normal working state again.
2. The MCU resetting method according to claim 1, wherein a CAN controller is built in the MCU unit,
the CAN controller is used for sending self state information to the MCU unit;
and the MCU unit is also used for stopping feeding the dog feeding signal back to the watchdog unit when the self state information of the CAN controller is abnormal working state information.
3. An MCU reset system, wherein the system is adapted to perform an MCU reset method of any of claims 1 to 2;
the MCU reset system comprises a watchdog unit, a voltage conversion unit and an MCU unit;
the watchdog unit is connected with the MCU unit through a WDI pin, the output end of the voltage conversion unit is connected with the power input end of the MCU unit, and the reset output pin of the watchdog unit is connected with the power enable pin of the voltage conversion unit.
4. The MCU resetting system according to claim 3, wherein a CAN controller is built in an MCU unit of the resetting system, and the output end of the voltage conversion unit is connected with the power input end of the CAN controller.
5. An MCU resetting system according to claim 3, characterized in that the watchdog unit is provided with MR pins on which jumper caps are mounted.
6. The MCU resetting system according to claim 3, wherein the watchdog unit and the voltage conversion unit are directly powered by a power supply, the watchdog unit is a watchdog chip, the voltage conversion unit is a power supply chip, and the MCU unit is a microprocessor MCU.
7. A CAN bus anti-jamming device, characterized in that said device comprises an MCU reset system as defined in claim 4, and further comprises a CAN transceiver, said CAN transceiver being bidirectionally connected to said CAN controller.
8. The CAN bus anti-jamming device according to claim 7, wherein the anti-jamming device further comprises an isolation pulse transformer, the isolation pulse transformer is bidirectionally connected with the CAN transceiver through a connection line, a bias resistor is installed on the connection line, and the bias resistor is used for adjusting the voltage during signal transmission so that normal CAN signals CAN pass through the isolation pulse transformer.
9. The CAN bus anti-interference device according to claim 7, wherein the CAN transceiver is bidirectionally connected to the CAN controller, and specifically comprises: the CAN controller is in bidirectional connection with the CAN transceiver through a signal isolation device.
10. The CAN bus interference rejection unit as in claim 9, wherein said signal isolation unit is connected in parallel to a voltage isolation unit.
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| CN104750568A (en) * | 2015-04-14 | 2015-07-01 | 广州市智博光辉电气科技有限公司 | Abnormal forced resetting type watchdog circuit of microcontroller |
| CN206270937U (en) * | 2016-09-05 | 2017-06-20 | 南京大全自动化科技有限公司 | A kind of hardware watchdog circuit suitable for operating system |
| CN208479665U (en) * | 2018-07-23 | 2019-02-05 | 厦门普杰信息科技有限公司 | A kind of gateway of the house dog power reset circuit with delay function |
| CN208999992U (en) * | 2018-11-13 | 2019-06-18 | 厦门锐益达电子科技有限公司 | A kind of house dog protection circuit based on android system |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TW201423351A (en) * | 2012-12-10 | 2014-06-16 | Hon Hai Prec Ind Co Ltd | Reset circuit and electronic device |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104750568A (en) * | 2015-04-14 | 2015-07-01 | 广州市智博光辉电气科技有限公司 | Abnormal forced resetting type watchdog circuit of microcontroller |
| CN206270937U (en) * | 2016-09-05 | 2017-06-20 | 南京大全自动化科技有限公司 | A kind of hardware watchdog circuit suitable for operating system |
| CN208479665U (en) * | 2018-07-23 | 2019-02-05 | 厦门普杰信息科技有限公司 | A kind of gateway of the house dog power reset circuit with delay function |
| CN208999992U (en) * | 2018-11-13 | 2019-06-18 | 厦门锐益达电子科技有限公司 | A kind of house dog protection circuit based on android system |
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| CN112965412A (en) | 2021-06-15 |
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