Watchdog signal shielding module

Abstract

The present invention discloses a watchdog signal shielding module. One end of the module is connected to a ground pin of an MCU programmer, and the other end is connected to a test mode pin of a watchdog chip. The module can change the level of the output to the test mode pin depending on whether the MCU programmer is connected, causing the watchdog chip to enter or exit test mode. By utilizing one of the MCU programmer's GND pins as a programmer insertion indicator, the module automatically enters test mode without manual operation, significantly improving production efficiency.

Description

Technical Field

[0001] The present invention relates to the field of automotive electronics, and in particular to a watchdog signal shielding module for a watchdog chip in a functional safety design in automotive intelligent driving technology. Background Art

[0002] Intelligent driving technology has rapidly advanced in recent years, bringing convenience but also safety risks. To mitigate these risks, modern intelligent driving systems incorporate functional safety concepts and designs, with watchdog circuits being an essential component. While watchdog circuits can also be found in electronic circuits in other fields, they are most frequently used in automotive electronics.

[0003] The general logic of existing watchdog circuits is as follows: the watchdog is a monitoring circuit independent of the MCU and other processors. The MCU needs to send a feeding signal to the watchdog circuit within a specified time window. If the watchdog circuit does not receive the specified feeding signal for a certain number of times, the watchdog circuit will consider the MCU and other processors to be abnormal and generate a reset signal to reset the MCU.

[0004] Watchdog circuits can meet safety design requirements, but they can introduce some inconvenience to production testing. When the production line needs to update the MCU, the MCU stops the current program and also stops the watchdog function. If the watchdog circuit fails to receive a watchdog signal, it resets the MCU, which in turn causes the MCU update to fail.

[0005] To address this issue, existing watchdog chips feature a test mode. By inputting a specific voltage level to a specific pin, the watchdog chip enters test mode. In test mode, the watchdog circuit won't reset the MCU even if it doesn't receive a feed signal, thus ensuring a successful flash. However, entering test mode typically requires manual operation, such as inserting a jumper cap into a designated pin header. This manual operation significantly reduces production efficiency. Summary of the Invention

[0006] The Summary of the Invention introduces a series of simplified concepts, which are simplifications of existing technologies in the field and are further described in detail in the Detailed Description of the Invention. The Summary of the Invention is not intended to define the key features and essential features of the claimed technical solution, nor is it intended to determine the scope of protection of the claimed technical solution.

[0007] The technical problem to be solved by the present invention is to provide a watchdog signal shielding module which can shield the watchdog signal without manual operation when the MCU is refreshed.

[0008] In order to solve the above technical problems, the present invention provides a watchdog signal shielding module, one end of which is connected to a ground pin of the MCU burner, and the other end of which is connected to the watchdog chip test mode pin TM;

[0009] It can change the level state of the output to the test mode pin TM according to whether the MCU burner is connected, so that the watchdog chip enters or exits the test mode.

[0010] Optionally, the watchdog signal shielding module is further improved to include:

[0011] A first resistor R1, a first end of which is connected to the ground pin of the MCU programmer, and a second end of which is connected to the power supply voltage VCC;

[0012] A PNP transistor P has a base connected to the ground pin of the MCU burner, an emitter connected to the power supply voltage VCC, and a collector connected to the test mode pin TM of the watchdog chip and connected to the ground via a second resistor R2.

[0013] Optionally, the watchdog signal shielding module is further improved so that when the MCU programmer is not connected, the P base of the PNP transistor is at a high level, the transistor is not turned on, and the watchdog chip does not enter the test mode;

[0014] When the MCU programmer is connected, the P base of the PNP transistor is at a low level, the transistor is turned on, and the watchdog chip enters the test mode.

[0015] Optionally, the watchdog signal shielding module is further improved to include:

[0016] A first resistor R1, a first end of which is connected to the ground pin of the MCU programmer, and a second end of which is connected to the power supply voltage VCC;

[0017] A PNP transistor P, whose base is connected to the ground pin of the MCU burner, whose emitter is connected to the power supply voltage VCC, and whose collector is connected to one end of the third resistor R3 and the enable end of the pulse detection circuit PD;

[0018] NPN transistor N, its base is connected to the output terminal of the pulse detection circuit PD, its emitter is connected to the ground, and its collector is connected to the test mode pin TM of the watchdog chip;

[0019] The other end of the third resistor R3 is connected to the ground through the second resistor R2 and is connected to the test mode pin TM of the watchdog chip;

[0020] The pulse detection circuit PD has its input connected to the MCU reset pulse signal, which changes the level state of the output to the test mode pin TM according to whether the MCU is reset;

[0021] The MCU reset pulse signal is generated after the MCU finishes flashing the program. The MCU will run the new program only after the MCU reset pulse signal is generated.

[0022] Optionally, the watchdog signal shielding module is further improved, and the resistance of the second resistor R2 is at least 10 times that of the third resistor R3.

[0023] Optionally, the watchdog signal shielding module is further improved, the pulse detection circuit PD is a D trigger, its D end is connected to the P collector of the PNP transistor, its CP end is connected to the MCU reset pulse signal, and its Q end is connected to the N base of the NPN transistor.

[0024] Optionally, the watchdog signal shielding module can be further improved. When the MCU burner is connected, the D end of the D flip-flop is at a high level. When the MCU reset pulse signal arrives, the Q end of the D flip-flop outputs a high level, the NPN transistor N, and the watchdog chip test mode pin TM level are pulled low, and the watchdog chip exits the test mode.

[0025] In order to solve the above technical problems, the present invention provides a watchdog signal shielding module, comprising:

[0026] Its input end is connected to the reset output pin of the watchdog chip, its output end is connected to the reset pin of the MCU, and its enable end is connected to a ground pin of the MCU programmer;

[0027] The enable terminal is high by default, the digital switch is turned on by default, the reset signal can pass through the digital switch normally, and the MCU can be reset in case of abnormality;

[0028] When the MCU programmer is connected, the level signal of its enable terminal is pulled low, it is shut down, and the reset signal cannot be output to the MCU.

[0029] Optionally, the watchdog signal shielding module is further improved to be a digital switch DS.

[0030] When the MCU is flashing the program, the JTAG or DAP connector of the burner will be connected to the specific connector on the PCB board. The signal reference of the JTAG or DAP connector is as follows: Figure 1, there are generally multiple GND signals, and the corresponding pins of the burner are also connected to each other. Therefore, the present invention chooses to use one of the GND pins as a burner insertion indication. When the burner is inserted, it indicates that the flashing program is to be performed next and the watchdog needs to be shielded. The present invention can allow the watchdog chip to automatically enter the test mode test mode without manual operation. In a more preferred embodiment of the present invention, if the newly flashed software needs to be tested in an environment that supports the watchdog function after the flashing software is completed, the function of automatically recovering the watchdog can also be provided. There is no need to manually unplug the flashing connector, and the automatic link between flashing and testing can be met, which greatly improves production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings herein are intended to illustrate the general characteristics of methods, structures, and / or materials used in certain exemplary embodiments of the present invention, supplementing the descriptions in the specification. However, the drawings herein are schematic diagrams not drawn to scale and may not accurately reflect the precise structure or performance characteristics of any given embodiment. The drawings herein should not be interpreted as defining or limiting the range of values or properties encompassed by the exemplary embodiments of the present invention. The present invention is further described in detail below in conjunction with the drawings and specific embodiments:

[0032] Description of Reference Numerals

[0033] Figure 1 This is a diagram of the JTAG plug-in connection pins.

[0034] Figure 2 This is a schematic diagram of the structure of the second embodiment of the present invention Figure 1 .

[0035] Figure 3 This is a schematic diagram of the structure of the second embodiment of the present invention Figure 2 .

[0036] Figure 4 It is a structural diagram of the third embodiment of the present invention.

[0037] Figure 5 It is a structural diagram of the fourth embodiment of the present invention.

[0038] Figure 6 It is a structural diagram of the fifth embodiment of the present invention. DETAILED DESCRIPTION

[0039] The following describes the implementation manner of the present invention through specific specific embodiments. Those skilled in the art can fully understand other advantages and technical effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through different specific implementation manners, and the various details in this specification can also be applied based on different viewpoints, and various modifications or changes can be made without deviating from the overall design concept of the invention. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. The following exemplary embodiments of the present invention can be implemented in a variety of different forms and should not be interpreted as being limited to the specific embodiments described herein. It should be understood that these embodiments are provided to make the disclosure of the present invention thorough and complete, and to fully convey the technical solutions of these exemplary embodiments to those skilled in the art.

[0040] First embodiment;

[0041] The present invention provides a watchdog signal shielding module, one end of which is connected to a ground pin of an MCU burner, and the other end of which is connected to a test mode pin TM of a watchdog chip;

[0042] It can change the level state of the output to the test mode pin TM according to whether the MCU burner is connected, so that the watchdog chip enters or exits the test mode.

[0043] When the MCU is flashing the program, the JTAG or DAP connector of the burner will be connected to the specific connector on the PCB board. The signal reference of the JTAG or DAP connector is as follows: Figure 1 Typically, multiple GND signals are present, and the corresponding pins of a programmer are interconnected. Therefore, the present invention utilizes one of these GND pins as a programmer insertion indicator, indicating that a flash program is about to begin and that the watchdog timer needs to be disabled. Thus, the first embodiment of the present invention allows the watchdog chip to automatically enter test mode when the programmer's JTAG or DAP connector is connected, eliminating the need for manual operation.

[0044] Second embodiment;

[0045] like Figure 2 As shown, the present invention provides a watchdog signal shielding module, comprising:

[0046] A first resistor R1, a first end of which is connected to the ground pin of the MCU burner, and a second end of which is connected to the power supply voltage VCC, the power supply voltage VCC is 5V;

[0047] A PNP transistor P has a base connected to the ground pin of the MCU programmer, an emitter connected to the power supply voltage VCC, and a collector connected to the test mode pin TM of the watchdog chip and connected to the ground via a second resistor R2.

[0048] in, Figure 2 The figure shows the integration of the watchdog chip and the power management chip;

[0049] Figure 3 This is the case where the watchdog chip and the power management chip are set separately. In both cases, under the design concept of the present invention, the watchdog signal shielding module provided by the second embodiment can be applied. The subsequent embodiments are the same. Whether the watchdog chip and the power management chip are set independently does not affect the implementation of the technical solution of the present invention, and will not be repeated in detail.

[0050] The second embodiment works as follows:

[0051] When the MCU programmer is not connected, the P base of the PNP transistor is at a high level, the transistor is not conducting, and the watchdog chip does not enter the test mode;

[0052] When the MCU programmer is connected, the P base of the PNP transistor is at a low level, the transistor is turned on, and the watchdog chip enters the test mode.

[0053] It should be understood that when an element is referred to as being "connected" or "coupled" to another element, the element can be directly connected or coupled to another element, or there can be an intermediate element. Differently, when an element is referred to as being "directly connected" or "directly coupled" to another element, there is no intermediate element. In all the accompanying drawings, the same reference numerals always represent the same elements. In addition, it should also be understood that although the terms "first", "second", etc. can be used here to describe different elements, parameters, components, regions, layers and / or parts, these elements, parameters, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish an element, parameter, component, region, layer or part from another element, parameter, component, region, layer or part. Therefore, without departing from the teachings of exemplary embodiments of the present invention, the first element, parameter, component, region, layer or part discussed below may also be referred to as the second element, parameter, component, region, layer or part.

[0054] Third embodiment;

[0055] like Figure 4 As shown, the present invention provides a watchdog signal shielding module, comprising:

[0056] A first resistor R1, a first end of which is connected to the ground pin of the MCU programmer, and a second end of which is connected to the power supply voltage VCC;

[0057] A PNP transistor P, whose base is connected to the ground pin of the MCU burner, whose emitter is connected to the power supply voltage VCC, and whose collector is connected to one end of the third resistor R3 and the enable terminal of the pulse detection circuit PD;

[0058] NPN transistor N, its base is connected to the output terminal of the pulse detection circuit PD, its emitter is connected to the ground, and its collector is connected to the test mode pin TM of the watchdog chip;

[0059] The other end of the third resistor R3 is connected to the ground through the second resistor R2 and is connected to the test mode pin TM of the watchdog chip;

[0060] The pulse detection circuit PD has its input connected to the MCU reset pulse signal, which changes the level state of the output to the test mode pin TM according to whether the MCU is reset;

[0061] The MCU reset pulse signal is generated after the MCU finishes flashing the program. The MCU will run the new program only after the MCU reset pulse signal is generated.

[0062] Fourth embodiment;

[0063] like Figure 5 As shown, the present invention provides a watchdog signal shielding module, comprising:

[0064] A first resistor R1, a first end of which is connected to the ground pin of the MCU programmer, and a second end of which is connected to the power supply voltage VCC;

[0065] A PNP transistor P, whose base is connected to the ground pin of the MCU burner, whose emitter is connected to the power supply voltage VCC, and whose collector is connected to one end of the third resistor R3 and the enable terminal of the pulse detection circuit PD;

[0066] NPN transistor N, its base is connected to the output terminal of the pulse detection circuit PD, its emitter is connected to the ground, and its collector is connected to the test mode pin TM of the watchdog chip;

[0067] The other end of the third resistor R3 is connected to the ground through the second resistor R2 and is connected to the test mode pin TM of the watchdog chip;

[0068] The pulse detection circuit PD is a D flip-flop, whose D terminal is connected to the P collector of the PNP transistor, its CP terminal is connected to the MCU reset pulse signal, and its Q terminal is connected to the N base of the NPN transistor;

[0069] The MCU reset pulse signal is generated after the MCU finishes flashing the program. The MCU will run the new program only after the MCU reset pulse signal is generated. The resistance of the second resistor R2 is at least 10 times that of the third resistor R3.

[0070] When the MCU programmer is connected, the D terminal of the D flip-flop is high. When the MCU reset pulse signal arrives, the Q terminal of the D flip-flop outputs a high level, the NPN transistor N, and the watchdog chip test mode pin TM level are pulled low, and the watchdog chip exits the test mode.

[0071] Fifth embodiment;

[0072] like Figure 6 As shown, the present invention provides a watchdog signal shielding module, comprising:

[0073] Its input end is connected to the reset output pin of the watchdog chip, its output end is connected to the reset pin of the MCU, and its enable end is connected to a ground pin of the MCU programmer;

[0074] The enable terminal is high by default, the digital switch is turned on by default, the reset signal can pass through the digital switch normally, and the MCU can be reset in case of abnormality;

[0075] When connected to an MCU programmer, the level signal of its enable terminal is pulled low, it is shut down, and the reset signal cannot be output to the MCU;

[0076] In this embodiment, the watchdog signal shielding module is a digital switch DS.

[0077] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will also be understood that, unless expressly defined herein, 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, rather than being interpreted in an idealized or overly formal sense.

[0078] The present invention has been described in detail above by way of specific embodiments and examples, but these do not constitute limitations of the present invention. Without departing from the principles of the present invention, those skilled in the art may make many variations and improvements, which should also be considered within the scope of protection of the present invention.

Claims

1. A watchdog signal shielding module, characterized by: One end is connected to a ground pin of the MCU programmer, and the other end is connected to the test mode pin (TM) of the watchdog chip; It can change the level state of the output to the test mode pin (TM) according to whether the MCU burner is connected, so that the watchdog chip enters or exits the test mode; a first resistor (R1), a first end of which is connected to the ground pin of the MCU programmer, and a second end of which is connected to the power supply voltage (VCC); A PNP transistor (P), whose base is connected to the ground pin of the MCU burner, whose emitter is connected to the power supply voltage (VCC), and whose collector is connected to the test mode pin (TM) of the watchdog chip and is connected to the ground via a second resistor (R2); When the MCU programmer is not connected, the base of the PNP transistor (P) is at a high level, the transistor is not conducting, and the watchdog chip does not enter the test mode; When the MCU programmer is connected, the base of the PNP transistor (P) is at a low level, the transistor is turned on, and the watchdog chip enters the test mode.

2. The watchdog signal shielding module according to claim 1, characterized in that: include: a first resistor (R1), a first end of which is connected to the ground pin of the MCU programmer, and a second end of which is connected to the power supply voltage (VCC); A PNP transistor (P), whose base is connected to the ground pin of the MCU burner, whose emitter is connected to the power supply voltage (VCC), and whose collector is connected to one end of a third resistor (R3) and an enable terminal of a pulse detection circuit (PD); An NPN transistor (N), whose base is connected to the output terminal of the pulse detection circuit (PD), whose emitter is connected to the ground, and whose collector is connected to the test mode pin (TM) of the watchdog chip; a third resistor (R3), the other end of which is connected to the ground via the second resistor (R2) and is connected to the test mode pin (TM) of the watchdog chip; The pulse detection circuit (PD) has its input connected to the MCU reset pulse signal, which changes the level state of the output to the test mode pin (TM) according to whether the MCU burner is connected; The MCU reset pulse signal is generated after the MCU finishes flashing the program. The MCU will run the new program only after the MCU reset pulse signal is generated.

3. The watchdog signal shielding module according to claim 2, wherein: The resistance of the second resistor (R2) is at least 10 times that of the third resistor (R3).

4. The watchdog signal shielding module according to claim 2, wherein: The pulse detection circuit (PD) is a D flip-flop, whose D terminal is connected to the collector of a PNP transistor (P), whose CP terminal is connected to the MCU reset pulse signal, and whose Q terminal is connected to the base of an NPN transistor (N).

5. The watchdog signal shielding module according to claim 2, wherein: When connected to the MCU programmer, the D end of the D flip-flop is high. When the MCU reset pulse signal arrives, the Q end of the D flip-flop outputs a high level, the NPN transistor (N), and the test mode pin (TM) level of the watchdog chip is pulled low, and the watchdog chip exits the test mode.

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