CN111660957A - Automobile electronic control system - Google Patents

Abstract

The invention discloses an automobile electronic control system, and belongs to the technical field of automobile control. The system comprises: the device comprises a signal input unit, an electronic control unit and a power module; the electronic control unit comprises a CAN communication module and a microcontroller; the power module comprises an output interface circuit, a driver and an execution element; the man-machine communication module and the state quantity input module respectively comprise a sensor, a switch device and an amplifying circuit, and are used for completing signal transmission between the sensor and the microcontroller so as to convert the measured physical quantity into an electric signal and then process the electric signal according to a preset program; the CAN communication module comprises a CAN bus controller and a CAN bus transceiver, and the CAN bus controller and the CAN bus transceiver are used for data transmission. The invention uses the network design, simplifies the wiring on the automobile, reduces the number of electric nodes and the consumption of electric wires on the automobile, simplifies the assembly of the automobile and increases the reliability of information transmission.

Description

Automobile electronic control system

Technical Field

The invention relates to the technical field of automobile control, in particular to an automobile electronic control system.

Background

The automobile electronic technology is considered as a mark for measuring the development level of the modern automobile technology, the automobile electronic technology is the most important technical measure for developing new automobile types and improving automobile performance, and an automobile electronic control system becomes an important factor for evaluating the automobile performance, and is the most rapid field for updating the automobile industry. At present, automobiles gradually enter the computer control era, and the future development trend of the automobiles is electromechanical integration. Statistically, the cost of electronic products on luxury cars has exceeded 30% of the total cost of automobiles. In recent years, automotive electronics technology has played an increasingly important role in solving the problems of fuel consumption, emission, safety, and the like of automobiles. With the development of electronic technology, various high-precision technologies are widely applied to automobiles, and automobiles are converted into a complex device integrating electronics, control, machinery, computers, hydraulic pressure and communication by a mechanical system. With the complication of the requirements of people on automobiles, stricter safety and emission regulations, the automobile electronic technology is continuously developed.

However, the electronic control system of the automobile is increasingly complex, the communication between the internal module units of the automobile is also increasing, and the point-to-point mode cannot meet the development requirement of the automobile. Secondly, the electrical systems of the vehicle are complicated by the electrical devices on the vehicle, such as the electronic fuel injection system, the electronic suspension system, the navigation control, the anti-lock braking system, and the vehicle information system. In addition, most of the control systems of the prior art are composed of a large number of relays and complex protection circuits, which cause interference among numerous signals, and the dynamic performance of the automobile is not good.

Disclosure of Invention

In order to solve the problems of the prior art, an embodiment of the present invention provides an electronic control system for an automobile, where the system includes: a signal input unit, an Electronic Control Unit (ECU) and a power module; the signal input unit comprises a man-machine communication module and a state quantity input module; the Electronic Control Unit (ECU) comprises a CAN communication module and a microcontroller; the power module comprises an output interface circuit, a driver and an execution element;

the man-machine communication module and the state quantity input module are used for inputting signals and sending the input signals to the microcontroller through the CAN communication module; the man-machine communication module and the state quantity input module respectively comprise a sensor, a switch device and an amplifying circuit, and are used for completing signal transmission between the sensor and the microcontroller so as to convert the measured physical quantity into an electric signal and then process the electric signal according to a preset program;

the CAN communication module comprises a CAN bus controller and a CAN bus transceiver, and the CAN bus controller and the CAN bus transceiver are used for data transmission; the microcontroller is used for storing, calculating and analyzing the input signal, finishing a control function and outputting an execution instruction;

the output interface circuit is used for connecting the microcontroller, the driver and the execution device and amplifying the output signal, so that the microcontroller drives the execution element through the driver.

Optionally, the signal input unit further comprises an 8-bit parallel-in serial-out shift register 74HC165, and the 8-bit parallel-in serial-out shift register 74HC165 is used for realizing parallel-in serial-out extension.

Optionally, the signal input unit further comprises an eight-fold darlington tube ULN2803, where the eight-fold darlington tube ULN2803 is used to invert an input signal, and if the input signal is at a high level, the ULN2803 is used to invert the input signal, so as to obtain a low level; if the input signal is low, it is directly transmitted to the 8-bit parallel-input serial-output shift register 74HC 165.

Optionally, the microcontroller is an MCS-51 series SH79F1611 microcontroller.

Optionally, the Electronic Control Unit (ECU) further includes a switching value level conversion circuit, the switching value level conversion circuit includes an LM7805CT power supply conversion voltage stabilization chip, and the switching value level conversion circuit is configured to receive an input signal of the signal input unit and convert the input signal.

Optionally, the Electronic Control Unit (ECU) further includes a clock circuit, a crystal oscillator is connected between a first clock signal terminal and a second clock signal terminal of the microcontroller, and the clock circuit is formed by matching two capacitors of 20-40 pF.

Optionally, the Electronic Control Unit (ECU) further comprises a reset circuit, and a 10F electrolytic capacitor C4 is connected between the reset pin RST of the microcontroller and VCC to form the reset circuit.

Optionally, the CAN bus controller includes an MCP2515 crystal oscillator circuit.

The technical scheme provided by the embodiment of the invention has the following beneficial effects:

it is worth to be noted that the invention selects the hardware construction scheme of the CAN bus node, namely the microcontroller + the CAN bus controller + the CAN bus transceiver, to connect various automobile electronic devices into a network, and to send and receive information through the data bus. That is, the electronic control system for the automobile provided by the invention uses a networked design, simplifies the wiring on the automobile, reduces the number of electrical nodes and the consumption of electrical leads on the automobile, simplifies the assembly of the automobile and increases the reliability of information transmission; in addition, the automobile electronic control system provided by the invention CAN independently complete the control function of each module, CAN also send data to other control modules, and CAN acquire the data of any electronic control module through the CAN bus.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a simplified block diagram of an electronic control system for a vehicle according to an embodiment of the present invention;

FIG. 2 is a diagram of a microcontroller and its peripheral circuits according to an embodiment of the present invention;

FIG. 3 is a circuit diagram of a level shifter according to an embodiment of the present invention;

FIG. 4 is a clock circuit diagram provided by an embodiment of the present invention;

FIG. 5 is a diagram of a reset circuit according to an embodiment of the present invention;

FIG. 6 is a connection diagram of MCP2515 and SH79F1611 according to an embodiment of the present invention;

fig. 7 is a diagram of an internal functional structure of a PCA82C250 according to an embodiment of the present invention;

fig. 8 is a diagram of a CAN bus communication interface provided by an embodiment of the present invention;

FIG. 9 is a circuit diagram of an output interface circuit according to an embodiment of the present invention;

fig. 10 is a reset circuit diagram of a 74HC595 provided in an embodiment of the present invention;

fig. 11 is a circuit diagram of a driving circuit according to an embodiment of the present invention;

fig. 12 is a hardware structure diagram of a CAN bus node of an automotive electronic control system according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Application scenarios

Increasingly complex electronic control systems of automobiles and increasing communication among module units in the automobiles, point-to-point modes cannot meet the development requirements of the automobiles. Electrical equipment on automobiles, such as electronic fuel injection systems, electronic suspension systems, navigation controls, anti-lock braking systems, and automotive information systems, make the electrical systems on automobiles complex. Most of the existing automobile control systems are composed of a large number of relays and complex protection circuits, interference among numerous signals is caused, and the dynamic performance of the automobile is poor.

Noun interpretation

CAN bus: namely, Controller Area Network (Controller Area Network), the automotive electrical system is becoming increasingly complex, and it is a huge project if a traditional point-to-point data transmission mode is adopted. According to the investigation, one high-class car needs more than 400 wiring harness plugs, the total length of the wiring harness exceeds about 2.0m, the assembly is complex, and the failure rate is high. The CAN bus is a single network bus, and all peripheral module components CAN be directly hung on the bus. The current automobile electronic control technology mainly comprises engine electronic fuel injection control, automobile ATM control, a cruise system, ABS control, an EPS controller, a vehicle-mounted television, a vehicle-mounted telephone and the like; data exchange is needed among all control units (ECU), and real-time communication of the data is completed. In a single network formed by a CAN bus, a communication data block is adopted for coding, and a plurality of nodes CAN be connected. In practical applications, the number of nodes is limited by the electrical characteristics of the network hardware. PCA82C250 allows for attaching 110 nodes in the same network as CAN transceivers. Meanwhile, the CAN bus has strong error correction capability, supports differential data transmission, CAN adapt to environmental interference and CAN transmit data in a longer distance. And CAN provide data transmission rates up to 1 Mbit/s. The advantages of the CAN bus make it the most widely and reliably applicable field bus in automobiles. The CAN bus has real-time performance and low failure rate, and is excellent in serial data working environment.

Fig. 1 is a simplified block diagram of an electronic control system of an automobile according to an embodiment of the present invention, and referring to fig. 1, the system includes: signal input unit, Electronic Control Unit (ECU) and power module.

(1) The signal input unit comprises a man-machine communication module and a state quantity input module, and the man-machine communication module and the state quantity input module are used for inputting signals and sending the input signals to the microcontroller through the CAN communication module; and the man-machine communication module and the state quantity input module respectively comprise a sensor, a switch device and an amplifying circuit, and are used for completing signal transmission between the sensor and the microcontroller so as to convert the measured physical quantity into an electric signal and then process the electric signal according to a preset program.

It should be noted that each unit module included in the present invention is a digital signal module based on a CAN bus, a signal input part is mainly a switching device, and a plurality of switching devices are provided on an automobile, and the present invention specifically includes: lighting: high beam, dipped headlight, front fog light, back fog light, width indicating light, steering light, lighting lamp in vehicle, reading light; switches on the steering wheel: telephone answering and wiper adjusting switch; marking an instrument panel: safety belt prompting, hand brake, engine oil pressure indication, ABS locking prevention, vehicle door opening state, air bags and batteries; the key of the center console: the system comprises a four-door central control lock, an electronic hand brake switch, an air conditioner switch, a circulation mode, seat heating, seat ventilation, automatic slope stopping, an ESP switch, a tire pressure monitoring switch and an engine start-stop; other keys: rearview mirror adjustment, vehicle window control, vehicle window one-key locking, skylight switch, trunk switch and rearview mirror heating. After the signals of the switching device are subjected to signal acquisition and anti-interference processing, some signals can be input into a microcontroller of the electronic control unit to be processed (namely, a state quantity input module) according to a set program, and other signals are transmitted to an automobile instrument to be displayed (namely, a man-machine communication module).

It should be further noted that each switch corresponds to an IO interface of the microcontroller, and the microcontroller CAN determine that a certain switch is opened or closed by detecting the level of the I/O interface, and transmit the signal to the CAN bus for the CAN bus node of the vehicle lamp to use. Before the switch is pressed, the output end is at a high level, when the switch is pressed, if the action is perfect enough, the output end should immediately generate a stable low level, and the low level is kept until the finger leaves, but a user does not have the problems of professional training of pressing the switch and poor contact of a contact point of the switch, a delicate variable level contact process can be generated in the process of pressing the switch, the switch generates multiple on and off processes within a short time and becomes the 'jitter' of an output signal, so that a level signal which is jittered between Vcc and 0V can be generated at the output end, and for a device with high sensitivity such as a microcontroller, the misoperation can be generated by responding to the high level and the low level in the jitter process. In order to solve the above problems, since it is not known whether the switching value is input to the high level or the low level, the method adopted by the present invention is: if the input is high level, the eight-fold Darlington tube ULN2803 is used for inverting, namely when the input level signal is 1, the eight-fold Darlington tube ULN2803 is input, then low level can be output, namely high level is obtained, and then the high level can be sent to a jump machine to obtain low level; if the input is low, it is directly transferred to the 8-bit parallel-in serial-out shift register 74HC 165.

In addition, the number of switches on the automobile is large, the I/O port of the microcontroller is used up by an external memory, and the original abundant I/O port resources of the microcontroller become very tight, so that the invention also designs an 8-bit parallel input and serial output shift register 74HC165 in the signal input unit for realizing parallel input and serial output expansion.

(2) The Electronic Control Unit (ECU) comprises a CAN communication module and a microcontroller, wherein the CAN communication module comprises a CAN bus controller and a CAN bus transceiver, and the CAN bus controller and the CAN bus transceiver are used for data transmission; the microcontroller is used for storing, calculating, analyzing and processing the input signal, completing a control function and outputting an execution instruction.

It should be noted that the microcontroller is the core of the electronic control system of the automobile, and when designing the control system, a plurality of factors, such as control performance, application environment, power consumption, etc., need to be considered for the type selection of the microcontroller. That is, the digit number, the integrated peripheral module and the number of I/O interfaces of the microcontroller can be selected according to the complexity of the functions and the algorithm of the electric control system; it can also be selected from the group consisting of microcontroller at operating temperature, vibration resistance, and electromagnetic interference resistance.

Specifically, the MCS-51 series SH79F1611 microcontroller is selected on the basis of considering factors such as control performance, application environment, low power consumption and the like. The Intel company firstly develops a single-chip microcomputer Intel8051 specially used for an embedded system in 1980, all subsequent single-chip microcomputer products are collectively called MCS51, SH79F1611 reserves most functions of a standard 8051 chip and integrates 256 bytes of RAM and 2 16-bit timers/counters; the SH79F1611 is also internally provided with a 16K byte RAM for storing programs and a 1280 byte externally-extended RAM, and is integrated with a 2KB EEPROM for saving data after the system is powered off; the SH79F1611 is a compatible 8051 microcontroller with higher processing rate and higher efficiency, and has the characteristics of higher speed and better performance compared with the traditional 8051 chip under the same crystal oscillation frequency; two multi-input analog comparators, two paths of amplifiers, 12-bit integrated high-speed ADC and a motor control PWM module with dead time control are also arranged in the motor control system, so that the motor control system is quite suitable for controlling a direct-current stepping motor and a permanent magnet synchronous motor; in addition, a watchdog timer circuit is built in the circuit, and the functions of power-on reset, low-voltage reset and the like are realized, so that the circuit has 2 power-saving modes with low power consumption.

It should be noted that, when designing the electronic control system for an automobile provided by the present invention, it is necessary to design hardware circuits of the respective unit modules included in the electronic control system.

First, the design of the microcontroller and its peripheral circuits will be briefly explained:

(a) I/O ports: SH79F1611 has 44 programmable bidirectional I/O ports, and the I/O ports can be multiplexed with other functions. The control pin of a port control register (PxCry) is used as input or output, port data is registered in a register Px, and each I/O port is provided with an internal pull-up resistor controlled by the register PxPCry (x is 0-5, and y is 0-7). The 44 bidirectional I/O ports can also be configured as a second or third special function. The sharing priority is according to the rule that the external priority is the highest and the internal priority is the lowest. PxCR and PxPCR (x 0-5) may be modified when port sharing is allowed as another function, but these operations do not affect the state of the port until the other shared function is disabled. When port sharing is allowed as other functions, any write pin operation will only affect the data register; for a read operation, however, the port level is returned if the I/O is multiplexed into an interrupt function, and the value of the port register is returned if multiplexed into other functions. Fig. 2 is a diagram of a microcontroller and its peripheral circuits.

(b) VCC and GND (power supply terminal): the 40 th pin and the 20 th pin of the SH79F1611 are respectively a power supply end and a ground end, and the power supply voltage range of the SH79F1611 is direct current + 4.0V- +5.0V, and is generally + 5.0V. At present, most of vehicle-mounted power supplies on automobiles are +12V, a microcontroller requires a +5V direct-current power supply for power supply, the levels of the vehicle-mounted power supplies and the microcontroller are different, control signals cannot be directly input into an I/O (input/output) interface of the microcontroller, level conversion must be completed, and the microcontroller can process the signals. Therefore, to complete the conversion from +12V to +5V, the invention adopts the LM7805CT power supply conversion voltage stabilization chip to process the input signal, so that the input signal becomes a signal that can be received and identified by the microcontroller, the chip is convenient to use, the interface is simple, 100mA current can be provided, the power output requirement of the system is met, and the conversion circuit is shown in fig. 3.

(c) XTAL1 and XTAL2 (clock signal terminals): SH79F1611 employs a dual oscillator system architecture, and the high frequency oscillator supports 3 oscillator types: the micro-controller comprises an internal RC oscillator (27MHz), a crystal resonator (400kHz-16MHz) and a ceramic resonator (400kHz-16MHz), and has an on-chip oscillator structure, but a clock circuit is still needed for enabling the micro-controller to work. A crystal oscillator Y1 (or called crystal oscillator) is connected between a first clock signal end XTAL1(19 pin) and a second clock signal end XTAL2(18 pin) of the microcontroller, and an internal clock circuit is formed by matching two capacitors of 20-40 pF, as shown in FIG. 4 below. The method for generating the clock signal by using the crystal oscillator in a matching way is called as an internal clock mode, the frequency of the crystal oscillator determines the clock frequency of a system, if the crystal oscillator is 12MHz, the working frequency of a microcontroller system is 12MHz, and the crystal oscillator of 1.2-12 MHz is generally selected according to the requirement of the system on the working speed.

(d) RST (reset): the 9 th pin of the SH79F1611 microcontroller is the RESET pin RST (abbreviation for RESET), and when a very brief high point is input to the RST pin, the microcontroller RESETs. The reset pin is similar to the reset function key of some computers, and when the computer is running or dead, the computer can be restarted by pressing the reset key. The simplest reset circuit is an electrolytic capacitor C4 of 10F connected between RST terminal and VCC, as shown in FIG. 5. At the moment when the microcontroller is powered on, the voltage of the positive plate of the capacitor C4 is instantly changed into VCC, the electrolytic capacitor is equivalent to short circuit to the voltage at the moment, then VCC (high level) is equivalent to direct application to the RST end, and the singlechip is reset. The electrolytic capacitor is quickly charged, which corresponds to an open circuit for direct current, and the microcontroller starts to execute the program.

It should be noted that the present invention designs a hardware scheme of the CAN bus node, that is, a control mode of the microcontroller + the CAN bus controller + the CAN bus transceiver. The CAN bus controller selects MCP2515, wherein the MCP2515 CAN be connected with the microcontroller through an SPI interface, the MCP2515 CAN send standard and extended data frames and remote frames, 6 acceptance filter registers are arranged, unnecessary received messages CAN be shielded, and the connection between the MCP2515 and the microcontroller is realized through the SPI interface, so that the microcontroller CAN be selected at will; the CAN bus transceiver selects the PCA82C250, the PCA82C250 provides a differential data transmission function for the CAN bus and provides a receiving function for the CAN bus controller, the PCA82C250 is an interface between the CAN bus controller and a physical transmission medium, the speed CAN reach 1Mbit/s, the pin of the PCA82C250 is consistent with that of the PCA82C251, and the CAN bus transceiver has ideal passive performance under the non-power-on state and perfect anti-electromagnetic interference performance, and also provides a low-power consumption management function and supports a remote wake-up function.

Next, a brief description is given of the CAN bus controller MCP 2515:

(a) MCP2515 crystal oscillator circuit: the MCP2515 can operate with an on-chip oscillator or an off-chip clock source, the clock signal CLKOUT has an internal prescaler that can divide the crystal oscillator frequency by 1, 2, 4, 8 times, enable the CLKOUT function and select the prescaler ratio by setting a CANCNTRL register.

(b) Connection of MCP2515 to microcontroller: the MCP2515 may communicate directly with any microcontroller with an SPI interface and support SPI1, 1 and SPI0, 0 modes. The microcontroller SH79F1611 reads the data in the reception buffer through the SPI interface, and the microcontroller transmits the data to be transmitted to the transmission buffer of the MCP2515 through the SPI interface and then calls an RTS (request to send) command, thereby transmitting the data onto the CAN bus. CS, RESET, MOSI, MISO and SCK of the MCP2515 are respectively connected to P1.3-P1.7 pins of the SH79F1611, when the CS pin is at low level '0', the SH79F1611 selects the MCP2515, the microcontroller controls the MCP2515 to execute corresponding read-write operation through an SPI bus interface, an INT pin of the MCP2515 is connected with INT1 of the SH79F1611, the SH79F1611 can access the MCP2515 in an interrupt mode, and FIG. 6 is a connection diagram of the MCP2515 and the SH79F 1611.

In addition, a brief description of the CAN bus transceiver PCA82C 250:

in order to realize the communication function of the CAN bus, a CAN bus controller MCP2515 and a CAN bus transceiver PCA82C250 are adopted. The protocol controller in a CAN high-speed transceiver is connected to the transceiver via a serial data output line TxD and a serial data input line RxD, and the transceiver is connected to its pins of the bus line via its two differential reception and transmission capable bus terminals CANH and CANL, Vref providing a nominal output voltage of VCC/2 as a reference level for the CAN controller with an analog Rx input, S8 being used for the mode control reference output voltage, which is not needed since the SJA1000 has a digital input, and the transceiver uses a nominal supply voltage of 5V.

The MCP2515 protocol controller outputs a serial data stream to the TxD pin of the transceiver, and the internal pull-up function of the transceiver sets the TxD pin to a logic high level, i.e., the bus output driver is passive when open. And if TxD is a logic low, it will activate the output stage of the bus and produce a dominant signal level on the bus, the output drives CANH to provide a source output from Vcc and CANL to provide a pull-down output to GND, and the internal functional block diagram of PCA82C250 is shown in fig. 7.

In normal mode, the drive can send and receive data over CANH and CANL. The differential receiver converts the analog data on the bus to digital data for output to the RXD pin through a Multiplexer (MUX), the slope of the output signal on the bus lines is fixed and optimized, and low electromagnetic emissions (EME) are guaranteed.

Further, the CAN bus communication interface will be briefly described:

in the CAN bus communication interface, the PCA82C250 is employed as a bus driver. The interface of PCA82C250 and the CAN bus adopts certain anti-electromagnetic interference measures: the CANH and CANL pins of PCA82C250 are each connected to the CAN bus through a 5 resistor which acts as a current limiting to protect TJA1040 from overcurrent. A capacitor of 30pF is respectively connected in parallel between two pins of CANH and CANL and the ground, so that the function of filtering high-frequency interference on the bus is achieved, and certain electromagnetic radiation resistance is also achieved. And, a protective diode IN4148(D1, D2) is reversely connected between the two CAN bus access terminals and the ground, when a high negative voltage appears on the CAN bus, a certain over-protection effect CAN be achieved through the conduction of the diodes. The CAN bus communication interface diagram is shown in fig. 8.

In order to enhance the anti-electromagnetic interference capability of the CAN bus, TXCAN and RXCAN of the MCP2515 are connected with two pins TXD and RXD of the PCA82C250 through a high-speed optocoupler 6N 137. However, the isolated output channels must be separately powered.

(3) The power module comprises an output interface circuit, a driver and an execution element, wherein the output interface circuit is used for connecting the microcontroller, the driver and the execution device and amplifying an output signal, so that the microcontroller drives the execution element through the driver.

It should be noted that the microcontroller outputs digital signals, the output voltage is also very low, and generally it is not able to directly drive the execution element, so the output interface circuit and the driver are designed in the present invention, so that the microcontroller can drive the execution element through the output interface circuit and the driver.

The output interface circuit of the present invention adopts an 8-bit shift register 74HC595 and has a three-state output function, clocks of the shift register and the memory are respectively input by RCLK and SRCLK, data is input into the shift register at a rising edge of RCLK (shift register clock input), and data is input into the storage register at a rising edge of SRCLK (memory clock input). If the two clock input pins are connected together, the clock of the shift register is one pulse earlier than the clock of the storage register; the shift register has a serial shift input pin (SER) and a serial output (Q7') pin and an asynchronous reset pin (low), the memory register is parallel 8-bit with tri-state bus output, and when SRCLR is enabled (low), the data in the memory register is output onto the bus.

Fig. 9 is a circuit diagram of an output interface circuit, a CLR (low level) pin of 74HC595 is a clear 0 port, and in the present invention, a shift register clear 0 is required only when the system is powered on, so that the CLR terminal is connected to a reset circuit composed of a resistor R5 and a capacitor C25, and the reset circuit of 74HC595 is as shown in fig. 10 below.

In addition, the invention adopts a driving chip ULN2803 for power amplification, the ULN2803 is a single-chip bipolar high-power high-speed integrated circuit, which is composed of 8 groups of Darlington transistor arrays, corresponding resistor networks and clamping diode networks, the driving chip is a series product of high-voltage and large-current Darlington transistor arrays, has the characteristics of strong load carrying capacity, high current gain, wide temperature range, high working voltage and the like, is suitable for various systems requiring high-speed and high-power driving, is commonly used for driving a stepping motor and an LED, and has the capacity of simultaneously driving 8 groups of loads. FIG. 11 is a circuit diagram of a driving circuit, in which pins 11 to 18 of the ULN2803 shown in FIG. 11 are connected to a parallel 8-bit output interface of a 74HC595, and after the ULN2803, a field effect transistor IPD068P03L3G is selected as an amplifier, and the IPD068P03L3G is a P-channel enhancement type insulated gate field effect transistor.

Fig. 12 is a hardware structure diagram of a CAN bus node of an electronic control system of an automobile according to the present invention, and as shown in fig. 12, an engine control ECU, a suspension control ECU, a traction control ECU, an ABS control ECU, an ASR control ECU, a meter display ECU, an airbag ECU, a fault diagnosis ECU, an information center ECU, a central door lock ECU, a seat adjustment ECU, an electric door/window ECU, a front lamp ECU, and a rear lamp ECU of the automobile are connected via a CAN bus so as to communicate with each other and transmit data to each other.

It is worth to be noted that the invention selects the hardware construction scheme of the CAN bus node, namely the microcontroller + the CAN bus controller + the CAN bus transceiver, to connect various automobile electronic devices into a network, and to send and receive information through the data bus. That is, the electronic control system for the automobile provided by the invention uses a networked design, simplifies the wiring on the automobile, reduces the number of electrical nodes and the consumption of electrical leads on the automobile, simplifies the assembly of the automobile and increases the reliability of information transmission; in addition, the automobile electronic control system provided by the invention CAN independently complete the control function of each module, CAN also send data to other control modules, and CAN acquire the data of any electronic control module through the CAN bus.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (8)

1. An automotive electronic control system, characterized in that the system comprises: a signal input unit, an Electronic Control Unit (ECU) and a power module; the signal input unit comprises a man-machine communication module and a state quantity input module; the Electronic Control Unit (ECU) comprises a CAN communication module and a microcontroller; the power module comprises an output interface circuit, a driver and an execution element;

the man-machine communication module and the state quantity input module are used for inputting signals and sending the input signals to the microcontroller through the CAN communication module; the man-machine communication module and the state quantity input module respectively comprise a sensor, a switch device and an amplifying circuit, and are used for completing signal transmission between the sensor and the microcontroller so as to convert the measured physical quantity into an electric signal and then process the electric signal according to a preset program;

the CAN communication module comprises a CAN bus controller and a CAN bus transceiver, and the CAN bus controller and the CAN bus transceiver are used for data transmission; the microcontroller is used for storing, calculating and analyzing the input signal, finishing a control function and outputting an execution instruction;

the output interface circuit is used for connecting the microcontroller, the driver and the execution device and amplifying the output signal, so that the microcontroller drives the execution element through the driver.

2. The system according to claim 1, wherein the signal input unit further comprises an 8-bit parallel-input-serial-output shift register 74HC165, and the 8-bit parallel-input-serial-output shift register 74HC165 is used for realizing parallel-input-serial-output extension.

3. The system of claim 2, wherein the signal input unit further comprises an eight-fold darlington pipe ULN2803, wherein the eight-fold darlington pipe ULN2803 is configured to invert the input signal, and if the input signal is high, the ULN2803 is used to invert the input signal to obtain a low level; if the input signal is low, it is directly transmitted to the 8-bit parallel-input serial-output shift register 74HC 165.

4. The system of claim 1, wherein the microcontroller is an MCS-51 series SH79F1611 microcontroller.

5. The system according to claim 1, wherein said Electronic Control Unit (ECU) further comprises a switching value level shift circuit, said switching value level shift circuit comprising a LM7805CT power switching regulator chip, said switching value level shift circuit being configured to receive an input signal of said signal input unit and to shift said input signal.

6. The system according to claim 1, characterized in that said Electronic Control Unit (ECU) further comprises a clock circuit, a crystal oscillator is connected between the first clock signal terminal and the second clock signal terminal of the microcontroller, said clock circuit is formed by two 20-40 pF capacitors.

7. The system according to claim 1, characterized in that said Electronic Control Unit (ECU) further comprises a reset circuit consisting of a 10F electrolytic capacitor C4 connected between the reset pin RST of said microcontroller and VCC.

8. The system of claim 1 wherein the CAN bus controller comprises an MCP2515 crystal oscillator circuit.

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