Bootstrap circuit of automobile controller MCU and use method of bootstrap circuit

Abstract

The invention provides an automobile controller MCU bootstrap circuit and a using method thereof, and belongs to the technical field of automobile controllers. The circuit comprises a voltage stabilizing circuit, a rectifying circuit and a control circuit; the voltage stabilizing circuit is connected with the rectification circuit, the rectification circuit is connected with the control circuit, the voltage stabilizing circuit is used for being connected with a controller connector through an INPUT pin, the rectification circuit is used for rectification, and the control circuit outputs a signal to a start control pin of an MCU through a BootCFG pin so as to control the state of the start control pin; wherein when the voltage stabilizing circuit is connected to a low-level signal of the controller connector and is switched on, the control circuit outputs a high-level signal to a start control pin of the MCU, so that the MCU enters a CANboot mode. The method has the advantages of being easy to use, low in cost and high in safety, the troubleshooting efficiency of the controller can be greatly improved, the labor cost is reduced, and positive economic benefits are brought.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile controllers, and in particular to an automobile controller MCU bootstrap circuit and a use method thereof. Background Art

[0002] As the functions of automotive controllers become more complex and safety requirements increase, the complexity of software development is increasing. Various occasional failures are inevitable during the development process or after mass production. It is particularly important to quickly locate and solve the problems in automotive development.

[0003] Some faults are caused by abnormal changes in the MCU's internal NVM data. To analyze and locate these faults, the conventional approach involves opening the cover and soldering a JTAG cable to read the MCU's NVM data. However, this approach has drawbacks due to the varying controller installation locations. Controllers installed in locations like the engine compartment require higher IP ratings, typically IP6K9K. This makes disassembling the housing difficult, and the controller assembly is often rendered scrapped.

[0004] IP ratings are often expressed as "IP" followed by two numbers, which specify the degree of protection provided. The first digit indicates the device's ability to prevent the ingress of foreign objects. The second digit indicates the device's level of protection against water ingress. IP ratings of P6K9K protect against the ingress of dust and high-temperature, high-pressure water. The device under test must be able to withstand rigorous high-pressure, high-temperature washdown procedures. IP6K9K is the highest level of protection currently available.

[0005] In addition, some faults will reset the MCU system when reading data after connecting to JTAG, which may cause the fault to disappear, making it more difficult to locate the problem. Summary of the Invention

[0006] The present invention aims to solve the defects of the above solutions and provide a method without opening the cover and soldering JTAG, which can copy the NVM data of the faulty controller through the external interface of the connector for fault analysis and location.

[0007] In the first aspect, an embodiment of the present invention provides an automobile controller MCU bootstrap circuit, which includes: a voltage stabilizing circuit, a rectifier circuit and a control circuit; the voltage stabilizing circuit is connected to the rectifier circuit, and the rectifier circuit is connected to the control circuit. The voltage stabilizing circuit is used to be connected to the controller connector through the INPUT pin, the rectifier circuit is used for rectification, and the control circuit outputs a signal to the startup control pin of the MCU through the Boot_CFG pin to control the startup control pin state; wherein, when the voltage stabilizing circuit is connected to the low-level signal of the controller connector and is turned on, the control circuit outputs a high-level signal to the startup control pin of the MCU, so that the MCU enters the CANboot mode.

[0008] Preferably, the voltage stabilizing circuit adopts a voltage stabilizing diode, the rectifier circuit adopts a rectifier diode, and the control circuit adopts a transistor. The control circuit transistor has a control electrode, a first electrode and a second electrode. The control electrode of the control circuit transistor is connected to the rectifier circuit, the first electrode of the control circuit transistor is connected to the power supply, and the second electrode of the control circuit transistor is connected to the Boot_CFG pin.

[0009] Preferably, it also includes: an anti-reset circuit, one end of the anti-reset circuit is connected to the control circuit and connected to the Boot_CFG pin, and the other end of the anti-reset circuit outputs a signal through the DIS_WD pin and is connected to the watchdog enable pin of the system basic chip to prevent the system basic chip from sending a reset signal.

[0010] Preferably, the anti-reset circuit uses a transistor, the anti-reset circuit transistor has a control electrode, a first electrode and a second electrode, the control electrode of the anti-reset circuit transistor is connected to the Boot_CFG pin, the first electrode of the anti-reset circuit transistor is grounded, and the second electrode of the anti-reset circuit transistor is connected to the DIS_WD pin.

[0011] Preferably, a capacitor is connected between the control electrode and the first electrode of the control circuit transistor, and the capacitor is used to increase the switching speed of the control circuit transistor and reduce switching noise; a resistor is connected between the voltage regulator diode and the INPUT pin, and the resistor is used for current limiting control to protect the voltage regulator diode.

[0012] In the second aspect, an embodiment of the present invention provides a method for using a bootstrap circuit of an automobile controller MCU, which includes: step S1: setting the connection of the bootstrap circuit; step S2: setting the connection of the CAN transceiver; step S3: reading the NVM data inside the MCU through the CAN bus; the bootstrap circuit is the circuit described in any preferred embodiment of the first aspect.

[0013] Preferably, the step S1 includes: connecting the INPUT pin of the bootstrap circuit to the INPUT pin of the controller connector; and connecting the Boot_CFG pin of the bootstrap circuit to the startup control pin bootCFG of the MCU.

[0014] Preferably, the step S1 further includes: connecting the DIS_WD pin of the bootstrap circuit to the watchdog enable pin of the system basis chip; the bootstrap circuit is the circuit described in any one of the third to fifth preferred embodiments of the first aspect.

[0015] Preferably, step S2 includes: connecting the CAN transceiver to the CAN pin of the controller connector; connecting the CAN transceiver to the CAN pin of the MCU.

[0016] Preferably, step S3 includes: powering on the controller connector VB / GND; inputting a -24V voltage to the INPUT pin of the bootstrap circuit through the INPUT pin of the controller connector; inputting a high level to the system base chip through the WAKE_IN pin to start the MCU; the CAN bus host computer burns the reading program to the MCU; and running the reading program to read the NVM data through the CAN bus.

[0017] The present invention provides a method for quickly locating and troubleshooting controller on-site faults and after-sales faults without opening the cover or welding JTAG. It has the advantages of simple use, low cost and high safety, can greatly improve the efficiency of controller fault troubleshooting, reduce labor costs, and bring positive economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic structural diagram of a bootstrap circuit for an automotive controller MCU provided by an embodiment of the present invention;

[0019] Figure 2 A flowchart of another method for using an automotive controller MCU bootstrap circuit according to an embodiment of the present invention;

[0020] Figure 3 A schematic diagram of the connection relationship of a method for using a bootstrap circuit of an automobile controller MCU provided by an embodiment of the present invention;

[0021] Figure 4 Schematic diagram of an optional specific implementation method of step S1 in an embodiment of the present invention;

[0022] Figure 5 This is a flowchart of an optional specific implementation method of step S3 in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] To enable those skilled in the art to better understand the technical solutions of the present invention, exemplary embodiments of the present invention are described below in conjunction with the accompanying drawings, including various details of the embodiments of the present invention to facilitate understanding. These details should be considered merely exemplary. Therefore, those skilled in the art should recognize that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present invention. Similarly, for the sake of clarity and conciseness, descriptions of well-known functions and structures are omitted in the following description.

[0024] In the absence of conflict, the various embodiments of the present invention and the various features therein may be combined with each other.

[0025] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0026] The terms used herein are only used to describe specific embodiments and are not intended to limit the present invention. As used herein, the singular forms "a" and "the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It will also be understood that when the terms "comprising" and / or "made of" are used in this specification, the presence of the features, wholes, steps, operations, elements and / or components is specified, but the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or groups thereof is not excluded. Similar words such as "connected" or "connected" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect.

[0027] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. It will also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and the present invention, and will not be interpreted as having an idealized or overly formal meaning unless expressly defined as such herein.

[0028] In the technical solution of the present invention, the collection, storage, use, processing, transmission, provision and disclosure of user personal information involved are in compliance with the provisions of relevant laws and regulations and do not violate public order and good morals. The use of user data in this technical solution complies with relevant national laws and regulations (for example, the "Information Security Technology Personal Information Security Specification", etc.). For example: corresponding prescribed measures are taken to control access to personal information; the display of personal information is subject to prescribed restrictions; the purpose of using personal information does not exceed the scope of direct or reasonable connection; when using personal information, clear identity reference is eliminated to avoid precise positioning of specific individuals.

[0029] This invention provides a software fault location solution that eliminates the need for opening the cover or soldering JTAG pins. A bootstrap circuit is designed to control the MCU's startup mode by reserving a bootstrap control interface on the connector. Before powering on the controller, a negative 24V voltage is applied to the INPUT pin. Then, when the controller is powered on, the bootstrap circuit changes the voltage level of the MCU's bootCFG pin, causing the MCU to enter CANboot mode. In CANboot mode, NVM data is read via the CAN bus, the NVM data of the faulty component is saved, and then burned into a development sample for fault location. This solution is simple to operate, low-cost, and highly practical.

[0030] An MCU (Microcontroller Unit) chip, or microcontroller unit, is an integrated circuit chip that integrates a central processing unit (CPU), memory (ROM, RAM), and various peripheral interfaces (such as input and output pins, timers, serial ports, etc.), equivalent to a microcomputer system. MCU chips are sometimes also called single-chip microcomputers.

[0031] JTAG (Joint Test Action Group) is an interface. JTAG has a download function that can download software to FLASH. JTAG has a debug bug function (DEBUG). JTAG also has a boundary scan function that can access the signal logic status inside the chip and the status of the chip pins.

[0032] MCUs all have internal memory. Memory includes both volatile and non-volatile memory. A microcontroller's (MCU) non-volatile memory (NVM) is a crucial component for storing data and programs. It retains data even after a power outage or reset. MCU NVM typically includes flash memory, EEPROM (electrically erasable programmable read-only memory), and FRAM (non-volatile RAM).

[0033] The CAN bus (Controller Area Network), also known as the controller area network bus, is a widely used fieldbus. Currently, high-speed automotive network systems all adopt standards based on the CAN bus, particularly the widely used ISO 11898 international standard. The CAN bus has become standard in automotive configurations. Nodes in a CAN network are not divided into master and slave groups, resulting in flexible communication and strong network scalability.

[0034] The MCU chip has a CAN bus, which can be used to read data from the chip's memory. The MCU chip has a CANboot mode; in CANboot mode, data in the MCU chip's NVM can be read through the CAN bus.

[0035] An embodiment of the present invention provides a bootstrap circuit for an automotive controller MCU, comprising: a voltage stabilizing circuit, a rectifier circuit, and a control circuit. The voltage stabilizing circuit is connected to the rectifier circuit, which is in turn connected to the control circuit. The voltage stabilizing circuit is connected to a controller connector via an INPUT pin, the rectifier circuit is used for rectification, and the control circuit outputs a signal to a startup control pin of the MCU via a Boot_CFG pin to control the startup control pin state.

[0036] When the voltage stabilizing circuit is connected to the low-level signal of the controller connector and is turned on, the control circuit outputs a high-level signal to the startup control pin of the MCU, causing the MCU to enter the CANboot mode.

[0037] In some embodiments, the voltage stabilizing circuit uses a voltage stabilizing diode, the rectifier circuit uses a rectifier diode, and the control circuit uses a transistor. The control circuit transistor has a control electrode, a first electrode, and a second electrode. The control electrode of the control circuit transistor is connected to the rectifier circuit, the first electrode of the control circuit transistor is connected to the power supply, and the second electrode of the control circuit transistor is connected to the Boot_CFG pin.

[0038] Figure 1 A schematic structural diagram of a car controller MCU bootstrap circuit provided by an embodiment of the present invention; Figure 1 As shown, in some embodiments, the voltage stabilization circuit uses a TVS diode D2, which is connected to the controller connector through the INPUT pin, so that the MCU enters the CANboot mode when the input voltage is -24V; the rectifier circuit uses a rectifier diode U3; the control circuit uses a PNP transistor Q2, the control electrode of the control circuit transistor is the base of Q2 connected to U3, the first electrode of the control circuit transistor is the emitter of Q2 connected to the power supply 5V or 3.3V system power supply, and the second electrode of the control circuit transistor is the collector of Q2 connected to the startup control pin of the MCU through the Boot_CFG pin output signal for controlling the startup control pin state.

[0039] In the bootstrap circuit described above, when a -24V voltage is input to the controller connector, TVS diode D2 breaks down. After D2 breaks down, PNP transistor Q2 turns on, and the Boot_CFG pin outputs a high level to the MCU's boot control pin, causing the MCU to enter CANboot mode. In CANboot mode, the NVM data is read through the CAN bus, saving the NVM data of the faulty component without opening the cover or soldering the JTAG.

[0040] TVS (Transient Voltage Suppression) diodes are designed to break down at a certain voltage level and conduct large amounts of current without causing damage.

[0041] A PNP transistor, or PNP type transistor, consists of two P-type semiconductors with an N-type semiconductor sandwiched between them. In a PNP transistor, current flows from the emitter. The PNP transistor operates as follows: the emitter is connected to a high level, the collector is connected to a low level, and the base is connected to a control signal. The emitter-base current, Ib, controls the emitter-collector current, Ic. When the PNP transistor is turned on, current flows from the emitter to the collector.

[0042] In some embodiments, the circuit further includes an anti-reset circuit, one end of which is connected to the control circuit and to the Boot_CFG pin, and the other end of which outputs a signal through the DIS_WD pin and is connected to the watchdog enable pin of the SBC (system basis chip) to prevent the system basis chip from issuing a reset signal.

[0043] In some embodiments, the anti-reset circuit uses a transistor, which has a control electrode, a first electrode, and a second electrode. The control electrode of the anti-reset circuit transistor is connected to the Boot_CFG pin, the first electrode of the anti-reset circuit transistor is grounded, and the second electrode of the anti-reset circuit transistor is connected to the DIS_WD pin.

[0044] like Figure 1 As shown, in some embodiments, the anti-reset circuit uses an NPN transistor Q1; the control electrode of the anti-reset circuit transistor is connected to the base of Q1 and the control circuit and is connected to the Boot_CFG pin, the first electrode of the anti-reset circuit transistor is connected to the emitter of Q1 and is grounded, and the second electrode of the anti-reset circuit transistor is connected to the collector of Q1 through the DIS_WD pin to output a signal to the watchdog enable pin of the SBC (system basis chip).

[0045] In the above bootstrap circuit, when the NPN transistor Q1 is connected to a high level, Q1 is turned on, pulling down the watchdog enable pin of the SBC, so that the watchdog function of the SBC is turned off, preventing the SBC from resetting the power supply or the microcontroller when the MCU has no feeding signal output.

[0046] An NPN transistor is an NPN-type transistor. It consists of two N-type semiconductors and one P-type semiconductor, with the P-type semiconductor in the center and two N-type semiconductors on either side. The emitter of an NPN transistor is grounded, the collector is connected to a high level, and the base is connected to a control signal. The base-emitter current, Ib, controls the collector-emitter current, Ic. When the NPN transistor is turned on, current flows from the collector to the emitter.

[0047] In some embodiments, a capacitor is connected between the control electrode and the first electrode of the control circuit transistor, and the capacitor is used to increase the switching speed of the control circuit transistor and reduce switching noise.

[0048] like Figure 1 As shown, in some embodiments, the control circuit transistor adopts a PNP transistor Q2, and a capacitor C1 is connected between the base (control electrode) and the emitter (first electrode) of the PNP transistor Q2 to increase the switching speed of the PNP transistor Q2 and reduce switching noise.

[0049] In some embodiments, a resistor is connected between the voltage regulator diode of the voltage regulator circuit and the INPUT pin, and the resistor is used for current limiting control to protect the voltage regulator diode of the voltage regulator circuit.

[0050] like Figure 1 As shown, in some embodiments, the voltage stabilizing diode of the voltage stabilizing circuit adopts a TVS diode D2, and a resistor R2 is connected between the TVS diode D2 and the INPUT pin to control and protect the TVS diode D2 to prevent excessive current from burning after breakdown.

[0051] In some embodiments, the reverse breakdown voltage of the TVS diode D2 is 24V.

[0052] Figure 2 A flowchart of a method for using a bootstrap circuit of an automobile controller MCU provided by an embodiment of the present invention; Figure 2 As shown, the method includes:

[0053] Step S1: Setting the connection of the bootstrap circuit;

[0054] Step S2: Setting up the connection of the CAN transceiver;

[0055] Step S3: Read the NVM data inside the MCU through the CAN bus.

[0056] In some embodiments, as Figure 3 、 Figure 4 As shown, step S1 includes:

[0057] Connect the INPUT pin of the bootstrap circuit to the INPUT pin of the controller connector;

[0058] Connect the Boot_CFG pin of the bootstrap circuit to the boot control pin bootCFG of the MCU (microcontroller).

[0059] In some embodiments, as Figure 3 、 Figure 4 As shown, step S1 further includes: connecting the DIS_WD pin of the bootstrap circuit to the watchdog enable pin of the SBC (system basis chip).

[0060] A system basis chip (SBC) is a standalone chip that integrates power, communications, monitoring and diagnostics, safety monitoring, and GPIO. SBCs are increasingly used in automotive electronics. Monitoring and diagnostic features within the SBC include wake-up inputs, watchdog timers, resets, interrupts, and fault outputs after circuit diagnosis.

[0061] In some embodiments, as Figure 3 As shown, step S2 includes:

[0062] Connect the CAN transceiver to the CAN pin of the controller connector;

[0063] Connect the CAN transceiver to the CAN pin of the MCU (microcontroller).

[0064] The CAN bus transmits data using differential signals. A CAN transceiver converts differential signals into TTL-level signals, or vice versa. A CAN transceiver converts digital signals into electrical signals on the CAN bus, or converts electrical signals into digital signals that can be processed by an MCU chip. Therefore, a CAN transceiver is required to connect the controller connector to the MCU.

[0065] In some embodiments, as Figure 5 As shown, step S3 includes:

[0066] Power on the controller connector VB / GND;

[0067] The controller connector inputs -24V voltage to the INPUT pin of the bootstrap circuit through the INPUT pin;

[0068] The controller connector inputs a high level to the system basis chip SBC through the WAKE_IN pin to start the MCU;

[0069] The CAN bus host computer burns the reading program to the MCU;

[0070] Run the reading program to read the NVM data through the CAN bus.

[0071] As described in the above embodiment, when the controller connector inputs a -24V voltage to the INPUT pin of the bootstrap circuit, the TVS diode D2 breaks down. After D2 breaks down, the PNP transistor Q2 turns on, and the Boot_CFG pin outputs a high level to the startup control pin of the MCU, causing the MCU to enter CANboot mode. In CANboot mode, data from the NVM can be read via the CAN bus. Then, the controller connector inputs a high level to the system basis chip (SBC) via the WAKE_IN pin to start the MCU. At this time, because the CAN transceiver is connected to the CAN pin of the MCU, the CAN transceiver can read data from the MCU's NVM. The program can be set to automatically read the NVM data via the CAN bus.

[0072] The present invention uses the above-mentioned bootstrap circuit and the method for using the bootstrap circuit to copy the NVM data of the faulty controller through the external interface of the connector for fault analysis and location without opening the cover and welding JTAG. Therefore, it has the beneficial effects of simple use, low cost and high safety, and can greatly improve the efficiency of controller fault troubleshooting.

[0073] Example embodiments have been disclosed herein, and although specific terms are employed, they are used and should be interpreted only in a general illustrative sense and not for purposes of limitation. In some instances, it will be apparent to those skilled in the art that, unless otherwise expressly indicated, features, characteristics, and / or elements described in conjunction with a particular embodiment may be used alone or in combination with features, characteristics, and / or elements described in conjunction with other embodiments. Therefore, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the scope of the invention as set forth in the appended claims.

Claims

1. A car controller MCU bootstrap circuit, characterized in that: include: A voltage stabilizing circuit, a rectifier circuit, and a control circuit; the voltage stabilizing circuit is connected to the rectifier circuit, which is connected to the control circuit; the voltage stabilizing circuit is connected to the controller connector via the INPUT pin; the rectifier circuit is used for rectification; and the control circuit outputs a signal to the MCU's startup control pin via the Boot_CFG pin to control the startup control pin state; When the voltage stabilizing circuit is connected to the low-level signal of the controller connector and is turned on, the control circuit outputs a high-level signal to the startup control pin of the MCU, so that the MCU enters the CANboot mode.

2. The circuit according to claim 1, wherein: The voltage stabilizing circuit adopts a voltage stabilizing diode, the rectifier circuit adopts a rectifier diode, and the control circuit adopts a transistor. The control circuit transistor has a control electrode, a first electrode, and a second electrode. The control electrode of the control circuit transistor is connected to the rectifier circuit, the first electrode of the control circuit transistor is connected to the power supply, and the second electrode of the control circuit transistor is connected to the Boot_CFG pin.

3. The circuit according to claim 2, characterized in that It also includes: an anti-reset circuit, one end of which is connected to the control circuit and connected to the Boot_CFG pin, and the other end of which outputs a signal through the DIS_WD pin to the watchdog enable pin of the system basis chip to prevent the system basis chip from issuing a reset signal.

4. The circuit according to claim 3, characterized in that The anti-reset circuit uses a transistor, which has a control electrode, a first electrode and a second electrode. The control electrode of the anti-reset circuit transistor is connected to the Boot_CFG pin, the first electrode of the anti-reset circuit transistor is grounded, and the second electrode of the anti-reset circuit transistor is connected to the DIS_WD pin.

5. The circuit according to claim 4, characterized in that A capacitor is connected between the control electrode and the first electrode of the control circuit transistor, and the capacitor is used to increase the switching speed of the control circuit transistor and reduce switching noise; a resistor is connected between the voltage regulator diode and the INPUT pin, and the resistor is used for current limiting control to protect the voltage regulator diode.

6. A method for using a car controller MCU bootstrap circuit, characterized in that: include: Step S1: Setting the connection of the bootstrap circuit; Step S2: Setting up the connection of the CAN transceiver; Step S3: Read the NVM data inside the MCU through the CAN bus; The bootstrap circuit is the circuit described in any one of claims 1 to 5.

7. The method according to claim 6, characterized in that The step S1 comprises: Connect the INPUT pin of the bootstrap circuit to the INPUT pin of the controller connector; Connect the Boot_CFG pin of the bootstrap circuit to the boot control pin bootCFG of the MCU.

8. The method according to claim 7, characterized in that The step S1 further comprises: Connect the DIS_WD pin of the bootstrap circuit to the watchdog enable pin of the system basis chip; The bootstrap circuit is the circuit described in any one of claims 3 to 5.

9. The method according to claim 6, 7 or 8, characterized in that Described step S2 comprises: Connect the CAN transceiver to the CAN pin of the controller connector; Connect the CAN transceiver to the CAN pin of the MCU.

10. The method according to claim 9, characterized in that Described step S3 comprises: Power on the controller connector VB / GND; The controller connector inputs -24V voltage to the INPUT pin of the bootstrap circuit through the INPUT pin; The controller connector inputs a high level to the system basis chip through the WAKE_IN pin to start the MCU; The CAN bus host computer burns the reading program to the MCU; Run the reading program to read the NVM data through the CAN bus.

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