Multi-chip reset protection circuit

Abstract

The utility model provides a multi-chip reset protection circuit, which belongs to the technical field of chip reset, and comprises an MCU peripheral reset circuit, a metering chip circuit peripheral reset circuit, a hardware reset circuit and a power supply monitoring circuit, the MCU peripheral reset circuit comprises a single chip microcomputer U1, a resistor R1 and a capacitor C1, the metering chip circuit peripheral reset circuit comprises a metering chip U3, and the hardware reset circuit comprises a hardware reset circuit and a power supply monitoring circuit. The hardware reset circuit comprises a serial port chip U2, and the serial port chip U2 is connected with the MCU through an I2C (Inter-Integrated Circuit); the power supply monitoring circuit comprises a power supply monitoring chip U4, a resistor R4 and a capacitor C4; and the key KEY 1 is bridged at two ends of the capacitor C4. According to the utility model, manual reset can be effectively carried out in time in an abnormal working state, the phenomena of messy codes, blurred screens and the like caused by inconsistent reset due to power supply voltage fluctuation are reduced, and the circuit has the advantages of low cost, high reliability and simple principle.

Description

Technical Field

[0001] The utility model belongs to the technical field of chip reset, in particular to a multi-chip reset protection circuit. Background Art

[0002] Chips such as MCU, metering chips, serial port chips, etc. are often used in the control circuit of dual power ATS conversion switches. Most chips have reset pins. The function of the reset pin is to restore the chip to the initial state, ensure that the program can be executed from the beginning, and clear the internal state or register of the chip to ensure that it can start and run correctly under abnormal conditions. Due to the uncertainty of the on-site adaptation environment, such as power fluctuations, peripheral interference, temperature, peripheral abnormalities, etc., the product often works abnormally. Therefore, it is necessary to ensure that most problems can be solved by resetting under abnormal conditions. At this time, a manual reset button will be added to the product.

[0003] In ATS products, two different reset methods are generally used to ensure the normal operation of the product, one is software reset and the other is hardware reset. Hardware reset refers to a method of restoring normal operation by manually changing the circuit state. The typical application is a button or knob. When the product is unresponsive or faulty, pressing the reset button can usually restore the product to normal operation; software reset is to restart the system through a software program, such as some peripheral reset circuits around the chip. It is generally divided into high-level reset and low-level reset, which are mainly selected based on new product regulations and actual needs.

[0004] The main reason for reset is power supply fluctuation. The normal operation of the chip is inseparable from power supply. When the power supply is unstable and the fluctuation range is large, it will directly cause the product failure rate to increase. If multiple chips are used in the same circuit board, the working voltage and reset voltage of different chips are different, and the response time of the chip is different. Reset at different times will cause abnormalities.

[0005] Currently, existing reset circuits cannot cope well with voltage fluctuations within a small range.

[0006] Therefore, in order to deal with the abnormalities caused by unstable power supply and different chip reset voltages and different startup times, it is urgent to develop a circuit that monitors the voltage to ensure that the voltage can be selectively reset at the same time when it reaches a certain threshold. Utility Model Content

[0007] The problem to be solved by the utility model is to provide a multi-chip reset protection circuit with low cost, high reliability and simple principle.

[0008] In order to solve the above technical problems, the technical solution adopted by the utility model is: a multi-chip reset protection circuit, including an MCU peripheral reset circuit, a metering chip circuit peripheral reset circuit, a hardware reset circuit and a power supply monitoring circuit.

[0009] The MCU peripheral reset circuit includes a single-chip microcomputer U1, a resistor R1 and a capacitor C1, the MCLK pin of the single-chip microcomputer U1 is connected to the negative electrode of the resistor R1 and the positive electrode of the capacitor C1 respectively, the positive electrode of the resistor R1 is connected to the power supply, and the negative electrode of the capacitor C1 is grounded;

[0010] The metering chip circuit peripheral reset circuit includes a metering chip U3, a resistor R8 and a capacitor C5. The metering chip U3 communicates with the single-chip computer U1 through the SPI port. The RESET pin of the metering chip U3 is connected to the negative electrode of the resistor R8 and the positive electrode of the capacitor C5 respectively.

[0011] The hardware reset circuit includes a serial port chip U2, which is interconnected with the MCU via I2C; the power monitoring circuit includes a power monitoring chip U4, a resistor R4 and a capacitor C4, the RESET pin of the power monitoring chip U4 is connected to the P03 pin of the serial port chip U2 via KEY R, and the RESET pin of the single-chip computer U4 is also connected to the negative electrode of the resistor R4 and the positive electrode of the capacitor C4 respectively; the positive electrode of the resistor R4 is connected to the power supply, the negative electrode of the resistor R4 is connected to the positive electrode of the capacitor C4, the negative electrode of the capacitor C4 is grounded, and the key KEY 1 is connected across the two ends of the capacitor C4.

[0012] Furthermore, the hardware reset circuit also includes a resistor R2, a resistor R3, a resistor R5, a resistor R6, a resistor R7, a capacitor C2 and a capacitor C3, wherein one end of the resistor R2 is connected to the power supply, and the other end is connected to the A0 pin of the serial port chip U2; one end of the resistor R3 is connected to the power supply, and the other end is connected to the A1 pin of the serial port chip U2; one end of the resistor R5 is connected to the power supply, and the other end is connected to the A2 pin of the serial port chip U2; one end of the resistor R6 is connected to the SCL pin of the serial port chip U2, and the other end is connected to the MCU through I2C_SCL; one end of the resistor R7 is connected to the SDA pin of the serial port chip U2, and the other end is connected to the MCU through I2C_SDA; one end of the capacitor C2 is connected to the power supply, and the other end is grounded; one end of the capacitor C3 is connected to the power supply, and the other end is grounded.

[0013] Furthermore, the power supply is a 3.3V power supply.

[0014] Due to the adoption of the above technical solution, the utility model has the following beneficial effects:

[0015] The utility model utilizes a single-chip microcomputer reset circuit composed of a single-chip microcomputer U1, a resistor R1, and a capacitor C1, a reset circuit and a peripheral circuit composed of a metering chip U3, a resistor R8, and a capacitor C5; and a manual reset button circuit composed of a power monitoring chip U4, a serial port chip U2, a button KEY1, and a plurality of capacitors and resistors. It can effectively and timely perform artificial reset under abnormal working conditions, reduces the phenomenon of garbled characters, flowery screens, etc. caused by inconsistent reset due to power supply voltage fluctuations, and has the advantages of low cost, high reliability, and simple principle. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be described in detail below with reference to the accompanying drawings and in combination with examples, and the advantages and implementation methods of the present invention will become more obvious. The contents shown in the accompanying drawings are only used to explain the present invention and do not constitute any limitation to the present invention. In the accompanying drawings:

[0017] Figure 1 The utility model is a MCU peripheral reset circuit diagram.

[0018] Figure 2 The utility model discloses a reset circuit diagram of a peripheral device of a metering chip circuit.

[0019] Figure 3 The utility model discloses a hardware reset circuit and a power supply monitoring circuit diagram. DETAILED DESCRIPTION

[0020] like Figures 1 to 3 As shown, the utility model is a multi-chip reset protection circuit, including an MCU peripheral reset circuit, a metering chip circuit peripheral reset circuit, a hardware reset circuit and a power supply monitoring circuit.

[0021] like Figure 1 As shown, the MCU peripheral reset circuit includes a single-chip microcomputer U1, a resistor R1 and a capacitor C1, the MCLK pin of the single-chip microcomputer U1 is connected to the negative electrode of the resistor R1 and the positive electrode of the capacitor C1 respectively, the positive electrode of the resistor R1 is connected to the 3.3V power supply, and the negative electrode of the capacitor C1 is grounded.

[0022] Since the reset pin is valid at a low level and the voltage across capacitor C1 cannot change suddenly, the MCLK pin is at a low level at the moment of power-on, and capacitor C1 is charged through resistor R1. When the capacitor C1 is fully charged, the MCLK pin is at a high level. Therefore, it is at a high level during normal operation and resets at a low level, meeting the reset requirements of the microcontroller U1.

[0023] like Figure 2As shown, the metering chip circuit peripheral reset circuit includes a metering chip U3, a resistor R8 and a capacitor C5. The metering chip U3 communicates with the microcontroller U1 through the SPI port. The RESET pin of the metering chip U3 is respectively connected to the negative electrode of the resistor R8 and the positive electrode of the capacitor C5, and a low-level reset is effective.

[0024] like Figure 3 As shown, the hardware reset circuit includes a serial port chip U2, and the serial port chip U2 is interconnected with the MCU through I2C. Among them, the hardware reset circuit also includes a resistor R2, a resistor R3, a resistor R5, a resistor R6, a resistor R7, a capacitor C2 and a capacitor C3, one end of the resistor R2 is connected to the 3.3V power supply, and the other end is connected to the A0 pin of the serial port chip U2; one end of the resistor R3 is connected to the 3.3V power supply, and the other end is connected to the A1 pin of the serial port chip U2; one end of the resistor R5 is connected to the 3.3V power supply, and the other end is connected to the A2 pin of the serial port chip U2; one end of the resistor R6 is connected to the SCL pin of the serial port chip U2, and the other end is connected to the MCU through I2C_SCL; one end of the resistor R7 is connected to the SDA pin of the serial port chip U2, and the other end is connected to the MCU through I2C_SDA; one end of the capacitor C2 is connected to the 3.3V power supply, and the other end is grounded; one end of the capacitor C3 is connected to the 3.3V power supply, and the other end is grounded.

[0025] The power monitoring circuit includes a power monitoring chip U4, a resistor R4 and a capacitor C4. The RESET pin of the power monitoring chip U4 is connected to the P03 pin of the serial port chip U2 through KEY R. The RESET pin of the microcontroller U4 is also connected to the negative electrode of the resistor R4 and the positive electrode of the capacitor C4 respectively; the positive electrode of the resistor R4 is connected to a 3.3V power supply, the negative electrode of the resistor R4 is connected to the positive electrode of the capacitor C4, the negative electrode of the capacitor C4 is grounded, and the button KEY 1 is connected across the two ends of the capacitor C4. By different reset voltages of the power monitoring chip U4, the MCU can be reset first, ensuring that the metering chip U3 can also be effectively reset when the MCU is reset.

[0026] Example:

[0027] It is known that the normal working voltage range of the single-chip microcomputer U1 is 3-3.6V, the MCLK pin is the main reset pin, the maximum working voltage is 5V, and the power supply of the single-chip microcomputer U1 is 3.3V. When the power supply voltage is ≤3V, the single-chip microcomputer U1 will perform a reset or stop working. It is recommended that the resistor R1 is ≤10K, the main reset pin-MCLK pin low level is effective, and the minimum reset time is 20 microseconds. Therefore, 3.3V is connected in series with the resistor R1 and then the capacitor C1 is connected to the ground. The value of the resistor R1 is 10K. The voltage across the capacitor C1 is 0 before power-on. After power-on, the current flows from 3.3V through the resistor R1 and the capacitor C1 to the ground. Since the voltage across the capacitor C1 cannot change suddenly, the voltage on the MCLK pin is also zero at the moment of power-on and remains at a low level for a period of time. During this period of time, the microcontroller U1 is reset; after a period of time, the capacitor C1 is fully charged, and the voltage across it rises to 3.3V. The reset is completed, and the microcontroller U1 starts to work normally. In order to meet the shortest reset time requirement, the value range of the capacitor C1 can be calculated by τ being approximately equal to RC, and the value of the capacitor C1 is 100nf.

[0028] The chip that controls the reset button (button KEY 1) is implemented through the serial port chip U2, and is interconnected with the MCU using I2C. The reset button is consistent with the reset level of the serial port chip U2, which is a low-level reset. Therefore, one end of the resistor R4 is connected to the 3.3V power supply, and the other end is connected to the capacitor C4. The other end of the capacitor C4 is grounded, and the button KEY 1 is connected across the two ends of the capacitor C4. The principle is consistent with the reset principle of the microcontroller U1. At the moment of power-on, the capacitor C4 is charged through the resistor R4. The capacitor C4 is equivalent to a wire, which is a low level. After charging is completed, the two ends of the capacitor C4 are equivalent to a short circuit, and the RESET pin returns to a high level. Pressing the button KEY 1 is equivalent to a short circuit at both ends of the capacitor C4, which is a low level, and it returns to a high level when released.

[0029] The metering chip U3 is powered by 3.3V and provides two different reset modes. The main one is hardware reset, which is completed through the external RESET pin. The RESET pin has a 47K pull-up resistor inside, so it is at a high level during normal operation. When the RESET pin has a low level greater than 20us, the metering chip U3 enters the reset state. When the RESET pin becomes a high level, the metering chip U3 will enter the normal working state from the reset state. Therefore, the hardware reset circuit is consistent with the microcontroller U1 circuit.

[0030] In addition, the utility model includes a power supply monitoring circuit to continuously monitor the analog power supply (AVCC). When the power supply voltage is lower than 2.5V±5%, the metering chip U3 will be reset.

[0031] Since the single-chip microcomputer U1 resets when it is lower than 3V, and the metering chip U3 resets only when the power supply voltage is lower than 2.5V±5%, there is a situation where the single-chip microcomputer U1 starts to reset when the voltage is in the range of 2.5+5% to 3V, but the metering chip U3 does not reset. Since the metering chip U3 often uses an LCD screen to display the power supply voltage, phase angle, frequency, etc. on the ATS port when used in conjunction, if the above situation occurs, due to the asynchrony of the two chips, it may cause abnormal situations such as display interface distortion or garbled data. Therefore, when using the hardware reset of the single-chip microcomputer U1, we will add the power monitoring chip U4, and directly share the reset pin of the power monitoring chip U4 - RESET pin with the reset pin of the manual reset button (key 1). When the key KEY1 is pressed, the two chips are forced to reset at the same time to avoid the above situation.

[0032] When selecting the power monitoring chip U4, different chips can be selected according to different voltage requirements. Here, a 3.08V monitoring chip is selected, and a reset operation will be performed when the power supply voltage is ≤3.08.

[0033] The above embodiments of the utility model are described in detail, but the above contents are only preferred embodiments of the utility model and cannot be considered to limit the scope of implementation of the utility model. All equivalent changes and improvements made within the scope of the utility model should still fall within the scope of this patent.

Claims

1. A multi-chip reset protection circuit, characterized in that: It includes an MCU peripheral reset circuit, a metering chip circuit peripheral reset circuit, a hardware reset circuit and a power monitoring circuit. The MCU peripheral reset circuit includes a single-chip microcomputer U1, a resistor R1 and a capacitor C1. The MCLK pin of the single-chip microcomputer U1 is respectively connected to the negative electrode of the resistor R1 and the positive electrode of the capacitor C1, the positive electrode of the resistor R1 is connected to the power supply, and the negative electrode of the capacitor C1 is grounded; the metering chip circuit peripheral reset circuit includes a metering chip U3, a resistor R8 and a capacitor C5. The metering chip U3 is intercommunication with the single-chip microcomputer U1 through the SPI port, and the RESET pin of the metering chip U3 is respectively connected to the negative electrode of the resistor R8 and the positive electrode of the capacitor C5; the hardware reset circuit includes a serial port chip U2, and the serial port chip U2 is interconnected with the MCU through I2C; the power monitoring circuit includes a power monitoring chip U4, a resistor R4 and a capacitor C4, and the RESET pin of the power monitoring chip U4 is connected through the KEY R is connected to the P03 pin of the serial port chip U2, and the RESET pin of the microcontroller U4 is also connected to the negative electrode of the resistor R4 and the positive electrode of the capacitor C4 respectively; the positive electrode of the resistor R4 is connected to the power supply, the negative electrode of the resistor R4 is connected to the positive electrode of the capacitor C4, the negative electrode of the capacitor C4 is grounded, and the key KEY 1 is connected across the two ends of the capacitor C4.

2. The multi-chip reset protection circuit according to claim 1, characterized in that: The hardware reset circuit also includes a resistor R2, a resistor R3, a resistor R5, a resistor R6, a resistor R7, a capacitor C2 and a capacitor C3, wherein one end of the resistor R2 is connected to the power supply, and the other end is connected to the A0 pin of the serial port chip U2; one end of the resistor R3 is connected to the power supply, and the other end is connected to the A1 pin of the serial port chip U2; one end of the resistor R5 is connected to the power supply, and the other end is connected to the A2 pin of the serial port chip U2; one end of the resistor R6 is connected to the SCL pin of the serial port chip U2, and the other end is connected to the MCU through I2C_SCL; one end of the resistor R7 is connected to the SDA pin of the serial port chip U2, and the other end is connected to the MCU through I2C_SDA; one end of the capacitor C2 is connected to the power supply, and the other end is grounded; one end of the capacitor C3 is connected to the power supply, and the other end is grounded.

3. The multi-chip reset protection circuit according to claim 1 or 2, characterized in that: The power supply is a 3.3V power supply.

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