CAN protocol conversion circuit and device with isolation function

Abstract

The utility model discloses a CAN protocol conversion circuit with an isolation function and a device thereof, the device comprises a micro-control unit, the micro-control unit is connected with a CAN transceiver, and the CAN transceiver is used as a physical layer interface element of a vehicle CAN communication system and is used for matching communication protocols among different ECUs; the circuit further comprises a power supply control circuit, power is supplied to the micro-control unit through a power supply and the power supply control circuit, the power supply control circuit supplies power to the CAN transceivers through isolated power supply modules, and different CAN transceivers are provided with independent isolated power supply modules for power supply. Therefore, power supply isolation of the micro-control unit and the secondary side of the CAN transceiver is realized, and equipment damage caused by power supply faults or voltage surges is prevented.

Description

TECHNICAL FIELD

[0001] The utility model belongs to vehicle control communication technical field, concretely relates to a CAN protocol conversion circuit and device with isolation function. BACKGROUND

[0002] ECU (Electronic Control Unit), the electronic control unit of car, also can be called "driving computer", by microprocessor (CPU), memory (ROM, RAM), input / output interface (I / O), analog-to-digital converter (A / D) and shaping, drive etc. Large scale integrated circuit composition. The original ECU is used to control the ignition and injection of engine, so the narrow sense is engine control unit, after the development of the electronic system on the car more and more, there is control chassis (ESP, ABS, ASR), there is control transmission (TCU of automatic transmission) etc., so later everybody all these control units collectively called electronic control unit, that is the ECU of broad sense. Including the EU of engine and other ECU, its basic composition includes 3 parts: input interface, microprocessor, output interface.

[0003] CAN protocol is a kind of serial communication protocol for automobile and industrial environment, it is also a kind of effective support distributed control system serial communication network. At present, in the trial production stage of sample vehicle, the communication protocol between different ECUs needs to be matched, in some cases, the conversion and isolation of communication protocol are needed. To meet the bus load balancing between different CAN branches, baud rate adjustment and other application scenarios. UTILITY MODEL CONTENT

[0004] The utility model aims at providing a kind of CAN protocol conversion device with isolation function, solve the communication protocol and baud rate matching problem between original car CAN communication protocol and target sample.

[0005] Technical scheme: a kind of CAN protocol conversion circuit with isolation function, the device includes micro control unit, the micro control unit is connected with CAN transceiver, CAN transceiver is used as the physical layer interface element of vehicle CAN communication system, for matching the communication protocol between different ECUs;

[0006] The circuit further includes power supply control circuit, micro control unit is powered by power supply and power supply control circuit, and the power supply control circuit is powered by the CAN transceiver of isolation power module, different CAN transceivers are all provided with independent isolation power module and are powered, thereby realizing the power isolation of secondary side of micro control unit and CAN transceiver, prevent the equipment damage caused by power failure or voltage surge.

[0007] Further, the circuit that isolation power module CAN transceiver is powered is as follows:

[0008] The isolation power module comprises an ISO1050DUBR chip, the VCC1 and VCC2 pins of which are connected to different power outputs respectively to realize the isolation between power domains.

[0009] The interface of each CAN transceiver is connected with a 120Ω resistor as a terminal resistor for reducing signal reflection and improving signal integrity.

[0010] The interface of the CAN transceiver comprises a protection diode PESD1CAN arranged for preventing electrostatic discharge damage.

[0011] Further, the micro control unit comprises an STM32F105VCT6V micro controller as a processing chip.

[0012] The control circuit of the power supply comprises:

[0013] A KA7805ERTF voltage stabilizer is used for controlling the output of +5V voltage.

[0014] A MIC5219-3.0YM5-TR linear voltage stabilizer is used for outputting 3.3V voltage.

[0015] 1N5819WS Schottky diodes are used for protecting the circuit.

[0016] Capacitors are used for constructing the filter circuit of the power supply.

[0017] Further, the device comprises an external programming port, an external power port, a serial communication interface, a buzzer, an indicator light and an external storage unit.

[0018] The utility model also includes a CAN protocol conversion circuit device with isolation function, which is used for packaging the above-mentioned circuit and electronic components, and further comprises an external power supply connected to realize the working of the circuit.

[0019] Beneficial effects: compared with the prior art, the utility model controls the independent isolation type CAN transceiver through the main control chip, and the power supply of the isolation type CAN transceiver adopts the isolation power module control power supply. The baud rate conversion and communication protocol conversion between CAN buses are not affected by power failure or voltage surge, meanwhile, the utility model provides electrical isolation at both ends of the CAN bus through the ISO1050DUBR chip, ensures the safe and reliable transmission of signals between different network nodes, and protects the micro controller and other sensitive circuits from the influence of electrical failure. The isolation improves the reliability and safety of the system. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1The circuit function block diagram of the utility model;

[0021] Figure 2 The isolated CAN transceiver power supply principle diagram;

[0022] Figure 3 The circuit structure diagram of micro control unit;

[0023] Figure 4 The power supply and filter circuit diagram;

[0024] Figure 5 The circuit diagram of two groups of CAN transceiver interfaces in the embodiment;

[0025] Figure 6 The circuit diagram of signal transmission;

[0026] Figure 7 The connection circuit diagram of user key;

[0027] Figure 8 The connection circuit diagram of buzzer;

[0028] Figure 9 The circuit diagram of external power supply port;

[0029] Figure 10 The circuit diagram of external programming interface;

[0030] Figure 11 The connection circuit of LED lamp. DETAILED DESCRIPTION

[0031] The utility model provides a CAN protocol conversion circuit and device with isolation function, Figure 1 The utility model discloses a circuit function structure, including STM32F105VCT6V microcontroller as minimum singlechip system (STM32F105VCT6VARM-MCU), based on TM32F105VCT6V microcontroller connection isolation type CAN transceiver 1 and isolation type CAN transceiver 2, for isolation type CAN transceiver 1 and isolation type CAN transceiver 2 adopt isolation power module 1 and isolation power module 2 independent control power supply, avoid the influence of power failure or voltage surge. The circuit still includes connecting power supply, and the power supply is provided with power control circuit, and isolation power module 1 and isolation power module 2 all belong to a part of power control circuit, namely, the utility model can adopt main power supply and is powered, and different power supply domains are connected by isolation power module 1 and isolation power module 2 to realize isolation function. The power supply domain refers to sharing a group of power supply, and the power supply of different functional modules is divided based on power control circuit (power management unit), contains a group of relevant circuits and logic, and independently controls power supply, and different voltage control and output can be realized by changing PMIC.

[0032] Figure 2 Isolation type CAN transceiver power supply principle diagram, the isolation type power module adopts ISO1050DUBR chip as the processor, the VCC1 and VCC2 pins of the chip are connected to different power supplies respectively to realize the isolation between power supply domains;An isolation type CAN transceiver is used as the physical layer interface element of the CAN communication system.

[0033] Figure 3 It is the connection circuit of TM32F105VCT6V microcontroller, and a minimum single-chip microcomputer system is constructed.

[0034] In order to enable those skilled in the art to more clearly understand the circuit structure and working of the utility model, the following mainly configures and explains the role of STM32F105VCT6V microcontroller:

[0035] ARM Cortex-M3 processor: 32-bit RISC architecture, the maximum working frequency can reach 72MHz.

[0036] Memory configuration: flash (Flash): 512KB, used for storing program code.

[0037] SRAM: 64KB, used for data storage and caching.

[0038] Clock system: internal clock source: HSI (high-speed internal clock) and LSI (low-speed internal clock).

[0039] External clock source: HSE (high-speed external clock) and LSE (low-speed external clock).

[0040] PLL (phase-locked loop): used for frequency multiplication and frequency division of clock frequency.

[0041] Power management: multiple power modes: running mode, sleep mode, standby mode and stop mode, to adapt to different power consumption requirements.

[0042] Peripheral interface:

[0043] USART (universal synchronous / asynchronous receiver / transmitter): support full-duplex serial communication.

[0044] SPI (serial peripheral interface): support high-speed synchronous communication.

[0045] I2C (inter-integrated circuit communication): support multi-master device communication.

[0046] USB (universal serial bus): support USB full-speed communication.

[0047] CAN (controller area network): support CAN bus communication.

[0048] Analog peripherals:

[0049] ADC (Analog-to-Digital Converter): 12-bit resolution, up to 16 channels.

[0050] DAC (Digital-to-Analog Converter): 2 channels of 8-bit DAC.

[0051] Timers:

[0052] Basic timers: for basic time measurement.

[0053] General-purpose timers: with input capture, output compare, PWM generation, etc.

[0054] Advanced timers: with dead-time control, complementary output, etc.

[0055] Real-time clock (RTC): supports timestamp and alarm functions.

[0056] Input / Output (I / O): GPIO (General Purpose Input / Output): 51 programmable I / O pins, supporting multiple function modes.

[0057] Debug and programming: SWD (Serial Wire Debug): supports debugging and programming through the SWD interface, Figure 10 .

[0058] JTAG (Joint Test Action Group): supports debugging and programming through the JTAG interface.

[0059] This schematic diagram implements CAN isolation mainly relies on two isolator chips: ISO1050DUBR (U4 and U7). The following are the specific steps and principles of implementing CAN isolation:

[0060] Isolator chip (ISO1050DUBR): ISO1050DUBR is a high-speed CAN bus isolator transceiver, used to achieve electrical isolation on the CANH and CANL lines. It can protect the microcontroller from electrical faults and transient voltages on the CAN network.

[0061] CAN interface configuration: there are two CAN interfaces, marked as CAN1 and CAN2 respectively.

[0062] CAN1 interface (J1) and CAN2 interface (J2) are connected to the corresponding CAN transceiver pins of the microcontroller, see Figure 5 .

[0063] Electrical connection: each CAN interface is isolated through the ISO1050DUBR chip.

[0064] The VCC1 and VCC2 pins of the ISO1050DUBR chip are connected to two power domains of the isolator respectively, ensuring electrical isolation. The GND1 and GND2 pins are connected to the respective ground, realizing isolation of the signal reference point.

[0065] Signal transmission: The RXD (Receive Data) and TXD (Transmit Data) pins transmit CAN signals between the microcontroller and the ISO1050DUBR, referring to Figure 6 .

[0066] The CANL and CANH pins are connected to the corresponding pins of the ISO1050DUBR, realizing isolated transmission of the CAN bus.

[0067] Power isolation: The VCC1 and VCC2 pins of the ISO1050DUBR chip are connected to different power sources respectively, ensuring isolation between power domains.

[0068] This isolation can prevent damage to the device caused by power failure or voltage surge.

[0069] Protection circuit: Each CAN interface has a 120Ω resistor (R1 and R7) for termination resistance, which helps to reduce signal reflection and improve signal integrity.

[0070] PESD1CAN (D4 and D5) is an ESD protection diode, used to protect the CAN interface from electrostatic discharge.

[0071] In combination with Figure 4 the power and filtering circuit: includes KA7805ERTF (U2) voltage regulator for outputting +5V voltage. MIC5219-3.0YM5-TR (U1) is an adjustable linear voltage regulator for outputting 3.3V voltage. 1N5819WS (D1, D2, D3) is a Schottky diode for protecting the circuit. Multiple capacitors (C1, C2, C3, C4, C5, C6, C7, C8) are used for power filtering.

[0072] In combination with Figure 5 the CAN interface circuit: there are two CAN interfaces, each provided with isolation protection by the ISO1050DUBR (U4 and U7) isolator chip. The CAN1 interface (J1) and the CAN2 interface (J2) are connected to the respective CAN transceiver pins of the microcontroller. Each CAN interface has a 120Ω resistor (R1 and R7) for termination resistance.

[0073] In combination with the use of the above-mentioned chip, the circuit according to the present application further comprises:

[0074] (1) Power and ground: VSS_5 (10) and VDD_5 (11) are the ground and power pins of the microcontroller. Multiple VSS and VDD pins provide ground and power connections for the microcontroller and other components.

[0075] (2) External storage and functions: PC13-TAMPER-RTC (7) can be a pin for the real-time clock. PC14-OSC32_IN (8) and PC15-OSC32_OUT (9) are the input and output pins of a 32.768 kHz crystal oscillator.

[0076] (3) Keys and reset: K4-6x6_TH KEY_RST (KEY_RST) is a reset button.

[0077] K4-6x6_TH KEY1 and K4-6x6_TH KEY2 are two user keys connected to PC2 and PC3, respectively, see Figure 7 .

[0078] (4) LED indicators: There are four LEDs (LED1-LED4) connected to PC15, PC14, PC1, PC0 for status indication, see Figure 11 .

[0079] (5) Buzzer: There is a buzzer circuit including MMBT5551 (Q1) transistor and BEER LS1 speaker, see Figure 8 .

[0080] (6) Serial communication: DSHP04TSGER (J3) can be a serial interface for debugging. CH330N (U10) is a USB-to-serial chip for communication between PC and the device.

[0081] (7) External power port: USB1 provides a USB interface for power supply and data transmission, see Figure 9 .

[0082] (8) Protection components: PESD1CAN (D4 and D5) are ESD protection diodes for protecting the CAN interface, see Figure 5 .

[0083] The utility model provides an electrical isolation at both ends of the CAN bus through the ISO1050DUBR chip, ensures the safe and reliable transmission of signals between different network nodes, and protects the microcontroller and other sensitive circuits from the influence of electrical faults. This isolation improves the reliability and safety of the system.

Claims

1. A CAN protocol conversion circuit with isolation function, characterized by, The circuit comprises a micro-control unit, which is connected with a CAN transceiver, the CAN transceiver being used as a physical layer interface element of a vehicle CAN communication system, for matching communication protocols between different ECUs. The circuit further comprises a power supply control circuit, which supplies power to the micro-control unit through a power supply and the power supply control circuit, and the power supply control circuit supplies power to the CAN transceivers through an isolation power supply module, different CAN transceivers are provided with independent isolation power supply modules for power supply, thus realizing power supply isolation of the secondary side of the micro-control unit and the CAN transceivers, preventing equipment damage caused by power failure or voltage surge.

2. The CAN protocol conversion circuit according to claim 1, characterized in that, The isolation power supply module comprises an ISO1050DUBR chip for control, VCC1 and VCC2 pins of the chip being connected to different power supply outputs, for realizing isolation between power supply domains. An interface of each CAN transceiver is connected with a 120Ω resistor as a terminal resistor, for reducing signal reflection and improving signal integrity. The interface of the CAN transceiver comprises a protection diode PESD1CAN for preventing electrostatic discharge damage.

3. The CAN protocol conversion circuit of claim 1, wherein, The micro-control unit comprises an STM32F105VCT6V micro-controller as a processing chip.

4. The CAN protocol conversion circuit of claim 1, wherein, The power supply control circuit comprises: a KA7805ERTF stabilizer for controlling output of +5V voltage; a MIC5219-3.0YM5-TR linear stabilizer for output of 3.3V voltage; a 1N5819WS Schottky diode for protection of the circuit; a capacitor for construction of a filter circuit of the power supply.

5. The CAN protocol conversion circuit of claim 1, wherein, The circuit is provided with an external programming port, an external power supply port, a serial communication interface, a buzzer, an indicator light and an external storage unit.

6. A CAN protocol conversion circuit device with isolation function, characterized by comprising: a CAN protocol conversion circuit device according to any one of claims 1 to 5; and an isolation function circuit. The device comprises the circuit of any one of claims 1-5, and further comprises an external power supply connected to realize work of the circuit.

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