Reset circuit and method for electronic scale with built-in lithium battery

Abstract

The invention discloses a reset circuit and method for an electronic scale with a built-in lithium battery, and the circuit comprises an NPN triode Q3, the base electrode of which is connected with a signal pin through a double voltage unit, and the emitter electrode of which is grounded; the collector electrode of the NPN triode Q3 is connected with the base electrode of the NPN triode Q4, and the collector electrode of the NPN triode Q4 is connected with the reset pin; the collector electrode of the NPN triode Q3 and the base electrode of the NPN triode Q4 are connected with a capacitor C33. Therefore, when the adapter is inserted, the reset operation can be triggered only under the condition that the MCU crashes; and if the MCU operates normally, the MCU continuously drives the NPN triode to be conducted so as to discharge the capacitor, and resetting is not triggered. On the premise that ID / MD design does not need to be changed and buttons are not additionally arranged, the power supply of the adapter is driven to reset only when a system is halted, and Flash damage or data loss cannot be caused.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of circuit design, and in particular to a reset circuit and method of an electronic scale with a built-in lithium battery. BACKGROUND

[0002] Most of the existing electronic scale products use glass panels, and the assembly process does not consider disassembly. When the measurement circuit fails and stops running, it is extremely difficult to disassemble and repair, and the rework cost is too high. Therefore, the existing electronic scale products use the following multiple schemes to achieve reset without disassembly: 1. Joint key (such as power key + volume key) triggers reset; 2. Add an independent reset key; 3. Set up a reset IC circuit to reuse the power key; 4. Insert an adapter to charge the capacitor for transient reset.

[0003] However, the above reset schemes also have inherent defects. The joint key scheme is not suitable for products with only one key. The scheme of adding an independent reset key requires special ID / MD design. The cost of the reset IC circuit is relatively high. Transient reset through an adapter cannot distinguish the system state. Even if the measurement circuit is running normally, it will be directly reset due to the insertion of the adapter, which may cause Flash damage and data loss risk. SUMMARY

[0004] The first aspect of the embodiment discloses a reset circuit of an electronic scale with a built-in lithium battery, specifically comprising: An NPN transistor Q3, whose base is connected to a signal pin CHRG_STATUS through a double voltage unit, and whose emitter is grounded; The collector of the NPN transistor Q3 is connected to the base of an NPN transistor Q4, and the collector of the NPN transistor Q4 is connected to a reset pin MCU_RST; The collector of the NPN transistor Q3 is connected to the base of the NPN transistor Q4 through a capacitor C33.

[0005] As an optional implementation, the double voltage unit is used to receive a PWM signal continuously output by an MCU microprocessor in a normal running state, and rectify and convert it into a direct current signal; The double voltage unit includes a capacitor C31 and a capacitor C32, a diode D4 is arranged between the capacitor C31 and the capacitor C32, and a base bias resistor R16 is arranged between the capacitor C32 and the NPN transistor Q3; The capacitor C31 is connected to the signal pin CHRG_STATUS through a current limiting resistor R15.

[0006] As an optional implementation, the signal pin CHRG_STATUS and the reset pin MCU_RST are connected to an MCU microprocessor; The MCU microprocessor continuously outputs a PWM signal to the signal pin CHRG_STATUS in a normal operation state, the double voltage unit outputs a rectified DC signal to the NPN transistor Q3 to maintain the NPN transistor Q3 in a conducting state.

[0007] As an optional implementation, the NPN transistor Q3 is used to turn on an external 5V power supply to charge the capacitor C33 in an off state.

[0008] As an optional implementation, the NPN transistor Q3 is also used to discharge the capacitor C33 to ground in a conducting state.

[0009] As an optional implementation, the MCU microprocessor stops transmitting a PWM signal to the signal pin CHRG_STATUS when it is dead, the double voltage unit stops outputting the DC signal to the NPN transistor Q3, the NPN transistor Q3 is turned off, and the external 5V power supply continuously charges the capacitor C33.

[0010] As an optional implementation, when the capacitor C33 is continuously charged to reach a conducting threshold, the NPN transistor Q4 is turned on, the reset pin MCU_RST is pulled down to a low level, and the MCU microprocessor is reset.

[0011] As an optional implementation, the MCU microprocessor enters a normal operation state after being reset, continuously outputs a PWM signal to the double voltage unit through the signal pin CHRG_STATUS, and the double voltage unit continuously outputs a DC signal to the NPN transistor Q3.

[0012] As an optional implementation, a resistor R19 is arranged between the collector of the NPN transistor Q4 and the reset pin MCU_RST. When the MCU microprocessor is in a normal operation state, the reset pin MCU_RST is pulled up to a high level by the resistor R19.

[0013] The second aspect of the embodiment discloses a dead reset method of an electronic scale with a built-in lithium battery, which specifically comprises: Insert an adapter to supply 5V power; Determine whether the MCU microprocessor continuously outputs a PWM signal; If the PWM signal is continuously output, the NPN transistor Q3 is turned on to discharge the capacitor C33; If the PWM signal is missing, the NPN transistor Q3 is turned off, and the capacitor C33 is continuously charged. The capacitor C33 turns on the NPN triode Q4 to reset the MCU microprocessor when charged to reach the conduction threshold.

[0014] Compared with the prior art, the embodiment has the following beneficial effects: When the adapter is inserted, only in the case of MCU crash, the reset operation is triggered; if the MCU is running normally, the NPN triode is continuously driven to be turned on to discharge the capacitor, and the reset is not triggered. Thus, without changing the ID / MD design and without adding a button, the system is only reset by the adapter power supply when the MCU crashes, and the Flash is not damaged or data is not lost. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0016] Figure 1 is a circuit principle schematic diagram of a reset circuit of an electronic scale with a built-in lithium battery disclosed by the embodiment; Figure 2 is a working flowchart of a reset method of an electronic scale with a built-in lithium battery disclosed by the embodiment. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments will be described clearly and completely below with reference to the drawings in the embodiments. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0018] Embodiment one Please refer to Figure 1 The reset circuit of the electronic scale with a built-in lithium battery disclosed by the embodiment comprises: The base of the NPN triode Q3 is connected to the signal pin CHRG_STATUS through a voltage doubling unit, and the emitter is grounded. The collector of the NPN triode Q3 is connected to the base of the NPN triode Q4, and the collector of the NPN triode Q4 is connected to the reset pin MCU_RST. The collector of the NPN triode Q3 is connected to the base of the NPN triode Q4.

[0019] In this embodiment, when the MCU microprocessor is in normal operation, it continuously sends a PWM signal to the double voltage unit through the signal pin CHRG_STATUS, and the double voltage unit sends a direct current signal to the NPN transistor Q3 based on the PWM signal, and the NPN transistor Q3 is turned on accordingly, and the capacitor C33 is continuously discharged.

[0020] Here, the capacitor C33 is continuously discharged, so its level cannot turn on the NPN transistor Q4 all the time.

[0021] Further, when the MCU microprocessor is dead, the PWM signal is interrupted, the direct current signal is interrupted, the NPN transistor Q3 is closed, causing the capacitor C33 to be continuously charged and not discharged, and its level will eventually turn on the NPN transistor Q4, so that the NPN transistor Q4 pulls low on the reset pin MCU_RST, triggering the reset of the MCU microprocessor.

[0022] Thus, without changing the ID / MD design and without adding a button, the system will only be driven to reset by the external power supply of the adapter when the MCU is dead, and will not cause Flash damage or data loss.

[0023] As an optional implementation, the double voltage unit is used to receive the PWM signal continuously output by the MCU microprocessor in normal operation, and rectify and convert it into a direct current signal; The double voltage unit includes a capacitor C31 and a capacitor C32, a diode D4 is arranged between the capacitor C31 and the capacitor C32, and a base bias resistor R16 is arranged between the capacitor C32 and the NPN transistor Q3. The capacitor C31 is connected to the signal pin CHRG_STATUS through the current limiting resistor R15.

[0024] As an optional implementation, the signal pin CHRG_STATUS is connected to the MCU microprocessor through the reset pin MCU_RST; The MCU microprocessor continuously outputs a PWM signal through the signal pin CHRG_STATUS in normal operation, and the double voltage unit outputs a direct current signal formed by rectification to the NPN transistor Q3, so as to maintain the NPN transistor Q3 in the on state.

[0025] As an optional implementation, the NPN transistor Q3 is used to connect the external 5V power supply in the off state to charge the capacitor C33.

[0026] As an optional implementation, the NPN transistor Q3 is also used to discharge the capacitor C33 to ground in the on state.

[0027] At this time, the capacitor C33 is continuously discharged when the MCU microprocessor is in normal operation, and its level cannot always turn on the NPN transistor Q4.

[0028] That is, the MCU microprocessor continuously turns off the process of performing reset on itself.

[0029] As an optional embodiment, the MCU microprocessor stops transmitting the PWM signal to the signal pin CHRG_STATUS when it is dead, the double voltage unit stops outputting the direct current signal to the NPN transistor Q3, the NPN transistor Q3 is closed, and the external 5V power supply continuously charges the capacitor C33.

[0030] As an optional embodiment, when the capacitor C33 is continuously charged to reach the conduction threshold, the NPN transistor Q4 is turned on, the reset pin MCU_RST is pulled low, and the MCU microprocessor is reset.

[0031] As an optional embodiment, the MCU microprocessor enters the normal operation state after reset, continuously outputs the PWM signal to the double voltage unit through the signal pin CHRG_STATUS, and the double voltage unit continuously outputs the direct current signal to the NPN transistor Q3.

[0032] At this time, when the MCU microprocessor is dead and the adapter is inserted for 5V power supply, the dead MCU microprocessor cannot turn off the process of performing reset on itself, and accordingly the capacitor C33 is charged to reach the conduction threshold, the NPN transistor Q4 is turned on, the reset pin MCU_RST is pulled low, and the MCU microprocessor is reset.

[0033] Since the MCU microprocessor itself is in a dead state at this time, there is no valid running data, and no data loss will occur, and the Flash is in an idle state at this time, and the reset operation will not cause damage to it.

[0034] As an optional embodiment, a resistor R19 is arranged between the collector of the NPN transistor Q4 and the reset pin MCU_RST. When the MCU microprocessor is in normal operation, the reset pin MCU_RST is pulled up to high level by the resistor R19.

[0035] In summary, when the adapter is inserted, only in the case of MCU dead, the reset operation will be triggered; if the MCU is in normal operation, it continuously drives the NPN transistor to be turned on to discharge the capacitor, and the reset will not be triggered. Without changing the ID / MD design and without adding a button, only when it is dead, the adapter will be powered to drive the reset, and it will not cause damage to the Flash or data loss.

[0036] Embodiment Two Please refer toFigure 2 The embodiment discloses a reset method of an electronic scale with a built-in lithium battery. 101, insert the adapter to supply 5V power.

[0037] The insertion of the adapter in the embodiment can trigger the subsequent state detection process and continuously charge the capacitor C33 when the MCU microprocessor is dead, so as to trigger the reset.

[0038] 102, determine whether the MCU microprocessor continuously outputs a PWM signal.

[0039] 103, the NPN transistor Q3 is turned on to discharge the capacitor C33.

[0040] Here, if the PWM signal is continuously output, a direct current signal is generated based on the PWM signal, and under the driving of the direct current signal, the NPN transistor Q3 continuously discharges the capacitor C33, and the measurement circuit of the entire electronic scale product is in steady-state operation.

[0041] 104, the NPN transistor Q3 is turned off, and the capacitor C33 is continuously charged.

[0042] Here, if the PWM signal is missing, the capacitor C33 will be continuously charged based on the 5V power supply of the adapter.

[0043] 105, when the capacitor C33 is charged to reach the turn-on threshold, the NPN transistor Q4 is turned on to perform reset on the MCU microprocessor.

[0044] Here, when the capacitor C33 reaches the turn-on threshold, the NPN transistor Q4 is turned on to perform reset.

[0045] Therefore, during normal operation, the insertion of the adapter does not affect the normal operation of the electronic scale product.

[0046] And when the MCU microprocessor of the electronic scale product is dead, the insertion of the adapter can trigger the charging of the capacitor C33 and the turn-on of the NPN transistor Q4 to perform reset on the MCU microprocessor.

Claims

1. A reset circuit for a built-in lithium battery electronic scale, characterized in that, include: The base of the NPN transistor Q3 is connected to the signal pin CHRG_STATUS via a voltage doubler unit, and its emitter is grounded. The collector of NPN transistor Q3 is connected to the base of NPN transistor Q4, and the collector of NPN transistor Q4 is connected to the reset pin MCU_RST. The collector of the NPN transistor Q3 is connected to the base of the NPN transistor Q4 by capacitor C33.

2. The reset circuit of a built-in lithium battery electronic scale according to claim 1, characterized in that, include: The voltage doubler unit is used to receive the PWM signal continuously output by the MCU microprocessor during normal operation and to rectify and convert it into a DC signal. The voltage multiplier unit includes capacitor C31 and capacitor C32. A diode D4 is disposed between capacitor C31 and capacitor C32. A base bias resistor R16 is disposed between capacitor C32 and NPN transistor Q3. The capacitor C31 is connected to the signal pin CHRG_STATUS via the current-limiting resistor R15.

3. The reset circuit of a built-in lithium battery electronic scale according to claim 2, characterized in that, include: The signal pin CHRG_STATUS and the reset pin MCU_RST are connected to the MCU microprocessor; In normal operation, the MCU microprocessor continuously outputs a PWM signal through the CHRG_STATUS signal pin, and the voltage doubler unit outputs a rectified DC signal to the NPN transistor Q3 to keep the NPN transistor Q3 in the on state.

4. The reset circuit of a built-in lithium battery electronic scale according to claim 3, characterized in that, include: The NPN transistor Q3 is used to connect an external 5V power supply in the off state to charge the capacitor C33.

5. The reset circuit for a built-in lithium battery electronic scale according to claim 4, characterized in that, include: The NPN transistor Q3 is also used to discharge the capacitor C33 to ground when it is in the on state.

6. The reset circuit of a built-in lithium battery electronic scale according to claim 4, characterized in that, include: When the MCU microprocessor crashes, it stops transmitting the PWM signal to the CHRG_STATUS signal pin, the voltage doubler unit stops outputting the DC signal to the NPN transistor Q3, the NPN transistor Q3 is turned off, and the external 5V power supply continuously charges the capacitor C33.

7. The reset circuit of a built-in lithium battery electronic scale according to claim 6, characterized in that, include: When capacitor C33 is continuously charged until it reaches the conduction threshold, NPN transistor Q4 is turned on, and the reset pin MCU_RST is pulled down to a low level to reset the MCU microprocessor.

8. The reset circuit of a built-in lithium battery electronic scale according to claim 7, characterized in that, include: After being reset, the MCU microprocessor enters normal operation mode and continuously outputs a PWM signal to the voltage doubler unit via the signal pin CHRG_STATUS. The voltage doubler unit continuously outputs a DC signal to the NPN transistor Q3.

9. The reset circuit of a built-in lithium battery electronic scale according to claim 8, characterized in that, include: A resistor R19 is provided between the collector of the NPN transistor Q4 and the reset pin MCU_RST; When the MCU microprocessor is in normal operation, the reset pin MCU_RST is pulled up to a high level by the resistor R19.

10. A reset method for a built-in lithium battery electronic scale, characterized in that, include: Insert the adapter to provide 5V power; Determine whether the MCU microprocessor continuously outputs a PWM signal; If the PWM signal continues to be output, the NPN transistor Q3 will turn on and the capacitor C33 will discharge. If the PWM signal is missing, the NPN transistor Q3 will be turned off, and the capacitor C33 will continue to charge. When capacitor C33 is charged to the conduction threshold, it turns on NPN transistor Q4 to reset the MCU microprocessor.

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