Parallel sampling resistor-based motor stall protection circuit

Abstract

The present invention relates to the field of motor stall protection circuits, and in particular to a parallel sampling resistor-based motor stall protection circuit, comprising: a motor driving module, comprising an H-bridge circuit; a current sampling module, comprising a first sampling resistor R9 and a second sampling resistor R91 which are connected in parallel, used for converting a motor current into a sampled voltage; a filtering module, comprising an inductor L2 and a first capacitor C3, wherein the inductor L2 has one end connected to a parallel node of the first sampling resistor R9 and the second sampling resistor R91, and the other end grounded by means of the first capacitor C3; and a control module, comprising an MCU, wherein the MCU is configured to periodically acquire a filtered sampled voltage and convert same into a corresponding current value, the MCU compares the current value with a preset reference current threshold, and when it is detected that the current value has remained above the reference current threshold for a preset duration, the motor driving module is controlled to cut off power to a motor. Therefore, the motor is effectively prevented from being in a stall state for a long time, thereby protecting the motor from damage.

Description

A motor stall protection circuit based on parallel sampling resistors Technical Field

[0001] This invention relates to the field of motor stall protection circuits, and more particularly to a motor stall protection circuit based on a parallel sampling resistor. Background Technology

[0002] Traditional electronic trash can circuits often lack a dedicated stall detection mechanism. When the motor drives the lid to open or close, if the lid is stuck, the motor may continue to run and enter a stalled state. In this case, the motor current will rise sharply, but traditional circuits cannot detect this abnormality in time, thus failing to take effective protective measures.

[0003] Even if some traditional circuits are designed with some form of protection mechanism, their response speed often lags behind the occurrence of stall. This means that the protection mechanism may not activate before the motor has been damaged or even caused a safety accident, and thus cannot effectively prevent the damage caused by stall.

[0004] Furthermore, traditional electronic trash can circuits typically use a fixed motor operating time to open or close the lid. However, this design does not take into account changes in battery power and differences in motor speed. When the battery is fully charged, the motor speed is high, and the actual time required for the lid to open or close may be much shorter than the set fixed time, causing the motor to stall for the remaining time and wasting electrical energy. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a motor stall protection circuit based on a parallel sampling resistor. This circuit monitors changes in motor current in real time using the parallel sampling resistor. When the motor stalls, the current increases rapidly, and the parallel sampling resistor quickly senses this change and feeds the signal back to the control circuit. Upon receiving the abnormal signal, the control circuit immediately cuts off the motor's power supply, effectively preventing the motor from remaining stalled for extended periods and protecting it from damage.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a motor stall protection circuit based on a parallel sampling resistor, comprising:

[0007] The motor drive module, including an H-bridge circuit, is used to control the forward and reverse rotation and start / stop of the motor.

[0008] The current sampling module consists of a first sampling resistor R9 and a second sampling resistor R91 connected in parallel. The first sampling resistor R9 and the second sampling resistor R91 connected in parallel are connected in series between the motor drive module and ground to convert the motor current into a sampling voltage.

[0009] The filtering module includes an inductor L2 and a first capacitor C3. One end of the inductor L2 is connected to the parallel node of the first sampling resistor R9 and the second sampling resistor R91, and the other end is grounded through the first capacitor C3.

[0010] The control module, connected to the output of the filtering module, includes an MCU. The MCU is used to periodically acquire the filtered sampled voltage and convert it into a corresponding current value. At the same time, the MCU compares the current value with a preset reference current threshold. When the current value is detected to continuously exceed the reference current threshold for a preset time, the control module cuts off the power supply to the motor.

[0011] Furthermore, the resistance values ​​of the first sampling resistor R9 and the second sampling resistor R91 are in the range of 1.1Ω-1.6Ω, and the equivalent resistance value range after parallel connection is 0.55Ω-0.8Ω.

[0012] Furthermore, the H-bridge circuit includes a first P-type transistor Q2, a first N-type transistor Q4, a second P-type transistor Q3, and a second N-type transistor Q5;

[0013] The first P-type transistor Q2 and the first N-type transistor Q4 are connected in series to form a forward rotation bridge arm. The emitter of Q2 is connected to the +3.3V power supply terminal. The collectors of the first P-type transistor Q2 and the first N-type transistor Q4 are respectively connected to the positive and negative terminals of the motor. The emitter of the first N-type transistor Q4 is grounded.

[0014] The second P-type transistor Q3 and the second N-type transistor Q5 are connected in series to form an inverting bridge arm. The emitter of the second P-type transistor Q3 is connected to the +3.3V power supply terminal, and the collectors of the second P-type transistor Q3 and the second N-type transistor Q5 are connected to the positive and negative terminals of the motor, respectively. The emitter of the second N-type transistor Q5 is grounded.

[0015] Furthermore, the base of the first P-type transistor Q2 is connected to the first drive signal terminal MODRV C of the MCU through the first current-limiting resistor R5; the base of the first N-type transistor Q4 is connected to the third drive signal terminal MODRV D of the MCU through the second current-limiting resistor R7; the base of the second P-type transistor Q3 is connected to the second drive signal terminal MODRV A of the MCU through the third current-limiting resistor R6; and the base of the second N-type transistor Q5 is connected to the fourth drive signal terminal MODRV B of the MCU through the fourth current-limiting resistor R8.

[0016] Furthermore, the H-bridge circuit also includes a filter capacitor C2, one end of which is connected to the collector of the second P-type transistor Q3, and the other end is connected to the collector of the first P-type transistor Q2.

[0017] Furthermore, the H-bridge circuit also includes a first diode D2 and a second diode D3, wherein the cathode of the first diode D2 is connected to the collector of the first N-type transistor Q4, and the anode of the first diode D2 is grounded; the cathode of the second diode D3 is connected to the collector of the second N-type transistor Q5, and the anode of the second diode D3 is grounded.

[0018] Furthermore, it also includes connector JP2, in which pins 2 and 3 are connected to the positive and negative terminals of the motor respectively, while pin 1 is connected to the +3.3V power supply terminal and pin 4 is grounded.

[0019] The beneficial effects of this invention are as follows: By monitoring the motor current in real time and cutting off the power supply in a timely manner when the motor is stalled, the ineffective energy consumption of the motor in a stalled state is avoided, thereby reducing the overall power consumption of the electronic equipment. At the same time, prolonged stalling can lead to motor overheating, damage, and even safety accidents. The stall protection circuit can promptly cut off the motor power supply, protecting the motor from damage and improving the reliability and service life of the equipment.

[0020] This invention employs a parallel sampling resistor and a simple filtering circuit, eliminating the need for complex sensors and detection circuits to achieve motor stall protection, thereby simplifying circuit design and reducing manufacturing costs. Furthermore, by setting a preset duration, such as 25ms, the power supply can be quickly cut off when the motor stalls, improving the system's response speed and protection effect. This circuit is suitable for various DC motor-driven electronic devices, such as electronic trash cans, automatic doors, and electric curtains, exhibiting strong versatility and adaptability. Attached Figure Description

[0021] Figure 1 is a circuit diagram of motor stall protection based on parallel sampling resistors. Detailed Implementation

[0022] Please refer to Figure 1. This invention relates to a motor stall protection circuit based on a parallel sampling resistor, comprising:

[0023] The motor drive module, including an H-bridge circuit, is used to control the forward and reverse rotation and start / stop of a DC motor.

[0024] The current sampling module consists of a first sampling resistor R9 and a second sampling resistor R91 connected in parallel. The first sampling resistor R9 and the second sampling resistor R91 connected in parallel are connected in series between the motor drive module and ground to convert the motor current into a sampling voltage.

[0025] The filtering module includes an inductor L2 and a first capacitor C3. One end of the inductor L2 is connected to the parallel node of the first sampling resistor R9 and the second sampling resistor R91, and the other end is grounded through the first capacitor C3.

[0026] The control module, connected to the output of the filtering module, includes an MCU. The MCU is used to periodically acquire the filtered sampled voltage and convert it into a corresponding current value. At the same time, the MCU compares the current value with a preset reference current threshold. When the current value is detected to continuously exceed the reference current threshold for a preset time, the control module cuts off the power supply to the motor.

[0027] Its specific working principle is as follows: the motor drive module controls the forward rotation, reverse rotation, and start / stop of the DC motor through an H-bridge circuit. The H-bridge circuit consists of four transistors, such as P-type and N-type transistors. By controlling the on / off state of these transistors, different directions of the motor and start / stop control can be achieved.

[0028] The current sampling module includes two sampling resistors, R9 and R91, connected in parallel. Because the equivalent resistance is reduced by connecting the resistors in parallel, the impact on the efficiency of the motor circuit is minimized. This parallel equivalent resistance is connected in series between the motor drive module and ground. When the motor is running, current flows through these two resistors, generating a sampling voltage. This sampling voltage is proportional to the motor current and can therefore be used to reflect the real-time current status of the motor.

[0029] The filtering module consists of inductor L2 and capacitor C3, used to filter the sampled voltage. The purpose of filtering is to remove high-frequency noise and interference signals from the sampled voltage, improving the stability and accuracy of the sampled signal. Inductor L2 is connected to the parallel node of the sampling resistor and grounded through capacitor C3, forming a low-pass filter circuit.

[0030] The core of the control module is the MCU (Microcontroller Unit). The MCU periodically samples the filtered voltage and converts it into a corresponding current value. The MCU compares the converted current value with a preset reference current threshold. If the current value continuously exceeds the reference current threshold for a preset time, such as 25ms, it determines that the motor is stalled. An internal timer in the MCU immediately controls the motor drive module to cut off the power supply to the motor upon detecting a stall, thus preventing energy waste and motor damage caused by prolonged stalling.

[0031] The beneficial effects of this solution are as follows: by monitoring the motor current in real time and promptly cutting off the power supply when the motor is stalled, it avoids the ineffective energy consumption of the motor in a stalled state, thereby reducing the overall power consumption of the electronic equipment. Prolonged stalling can lead to motor overheating, damage, and even safety accidents. The stall protection circuit can promptly cut off the motor power supply, protecting the motor from damage and improving the reliability and lifespan of the equipment.

[0032] This invention employs a parallel sampling resistor and a simple filtering circuit, eliminating the need for complex sensors and detection circuits to achieve motor stall protection, thereby simplifying circuit design and reducing manufacturing costs. Furthermore, by setting a preset duration, such as 25ms, the power supply can be quickly cut off when the motor stalls, improving the system's response speed and protection effect. This circuit is suitable for various DC motor-driven electronic devices, such as electronic trash cans, automatic doors, and electric curtains, exhibiting strong versatility and adaptability.

[0033] The resistance values ​​of the first sampling resistor R9 and the second sampling resistor R91 are set within the range of 1.1Ω-1.6Ω, a range carefully considered. Firstly, this range ensures that the sampling resistors have a minimal impact on the efficiency of the motor circuit. Since the sampling resistors are connected in series between the motor drive module and ground, excessively high resistance will increase the voltage drop during motor operation, thus reducing motor efficiency. Conversely, excessively low resistance may result in a low sampling voltage, affecting sampling accuracy. The 1.1Ω-1.6Ω range minimizes the impact on motor circuit efficiency while ensuring sampling accuracy. When two resistors with the same resistance value are connected in parallel, the equivalent resistance is half the resistance of a single resistor. Therefore, when the resistance values ​​of R9 and R91 are within the 1.1Ω-1.6Ω range, the equivalent resistance after parallel connection is (1.1Ω / 2)-(1.6Ω / 2), i.e., 0.55Ω-0.8Ω. The equivalent resistance after parallel connection further reduces the impact on the motor circuit while ensuring the accuracy and stability of the sampling voltage.

[0034] Furthermore, the H-bridge circuit includes a first P-type transistor Q2, a first N-type transistor Q4, a second P-type transistor Q3, and a second N-type transistor Q5;

[0035] The first P-type transistor Q2 and the first N-type transistor Q4 are connected in series to form a forward rotation bridge arm. The emitter of Q2 is connected to the +3.3V power supply terminal. The collectors of the first P-type transistor Q2 and the first N-type transistor Q4 are respectively connected to the positive and negative terminals of the motor. The emitter of the first N-type transistor Q4 is grounded.

[0036] The second P-type transistor Q3 and the second N-type transistor Q5 are connected in series to form an inverting bridge arm. The emitter of the second P-type transistor Q3 is connected to the +3.3V power supply terminal, and the collectors of the second P-type transistor Q3 and the second N-type transistor Q5 are connected to the positive and negative terminals of the motor, respectively. The emitter of the second N-type transistor Q5 is grounded.

[0037] When the motor needs to rotate forward, the control module turns on the second P-type transistor Q3 and the second N-type transistor Q5, while turning off the first P-type transistor Q2 and the first N-type transistor Q4. At this time, current flows from the +3.3V power supply terminal through Q3, into the motor, and then out of the motor, returning to ground via Q5. This forms a forward current path, driving the motor to rotate forward. When the motor needs to rotate in reverse, the control module turns on the first P-type transistor Q2 and the first N-type transistor Q4, while turning off the second P-type transistor Q3 and the second N-type transistor Q5. At this time, current flows from the +3.3V power supply terminal through Q2, but because Q3 is off, the current flows through the motor to Q4, and then back to ground from the emitter of Q4. This forms a reverse current path; note that the actual current direction is opposite to that during forward rotation, thus driving the motor to rotate in reverse. When the motor needs to stop, the control module turns off all four transistors Q2, Q3, Q4, and Q5 simultaneously. At this time, no current flows through the motor terminals, and the motor stops rotating. The H-bridge circuit offers several advantages: Flexible motor direction control: By controlling the on / off state of four transistors, the motor's forward, reverse, and stop functions can be flexibly controlled. The H-bridge circuit uses transistors as switching devices, resulting in lower on-resistance and faster switching speeds, thus improving circuit efficiency. The H-bridge circuit has a simple and clear structure, making it easy to implement and integrate. Enhanced circuit reliability: Transistors have a long lifespan and high reliability, improving the overall reliability of the motor drive circuit.

[0038] Furthermore, the base of the first P-type transistor Q2 is connected to the first drive signal terminal MODRV C of the MCU through the first current-limiting resistor R5; the base of the first N-type transistor Q4 is connected to the third drive signal terminal MODRV D of the MCU through the second current-limiting resistor R7; the base of the second P-type transistor Q3 is connected to the second drive signal terminal MODRV A of the MCU through the third current-limiting resistor R6; and the base of the second N-type transistor Q5 is connected to the fourth drive signal terminal MODRV B of the MCU through the fourth current-limiting resistor R8.

[0039] The base of the first P-type transistor Q2 is connected to the first drive signal terminal MODRV C of the MCU through the first current-limiting resistor R5. When MODRV C outputs a high level, Q2 is turned on; when it outputs a low level, Q2 is turned off. The base of the first N-type transistor Q4 is connected to the third drive signal terminal MODRV D of the MCU through the second current-limiting resistor R7. When MODRV D outputs a high level, Q4 is turned on; when it outputs a low level, Q4 is turned off. The base of the second P-type transistor Q3 is connected to the second drive signal terminal MODRV A of the MCU through the third current-limiting resistor R6. When MODRV A outputs a high level, Q3 is turned on; when it outputs a low level, Q3 is turned off. The base of the second N-type transistor Q5 is connected to the fourth drive signal terminal MODRV B of the MCU through the fourth current-limiting resistor R8. When MODRV B outputs a high level, Q5 is turned on; when it outputs a low level, Q5 is turned off.

[0040] The current-limiting resistor protects the MCU by limiting the current flowing into the transistor's base, preventing excessive current from damaging the MCU's output. Adjusting the resistance value of the current-limiting resistor can adjust the transistor's base current, thus affecting the transistor's switching speed and stability. The current-limiting resistor also reduces electromagnetic interference in the circuit, improving the circuit's anti-interference capability.

[0041] MCU control of the H-bridge circuit: Forward rotation control: The MCU outputs high levels through MODRV A and MODRV B, turning on Q3 and Q5. Simultaneously, MODRV C and MODRV D output low levels, turning off Q2 and Q4. Current flows from the +3.3V power supply through Q3, into the motor, then out of the motor, through Q5, and back to ground, driving the motor to rotate forward. Reverse rotation control: The MCU outputs high levels through MODRV C and MODRV D, turning on Q2 and Q4. Simultaneously, MODRV A and MODRV B output low levels, turning off Q3 and Q5. Current flows from the +3.3V power supply through Q2, but because Q3 is off, the current flows through the motor to Q4, then back to ground from the emitter of Q4, driving the motor to rotate in reverse. Stop control: The MCU outputs low levels through all four drive signal terminals MODRV A, B, C, and D, turning off Q2, Q3, Q4, and Q5. At this point, no current flows through the two ends of the motor, and the motor stops rotating.

[0042] The H-bridge circuit connects four transistors to the drive signal terminals of the MCU, enabling precise control of motor direction and start / stop. The current-limiting resistor plays a crucial role in protecting the MCU, stabilizing control, and reducing interference. By outputting different combinations of voltage levels, the MCU can flexibly control the on / off states of the transistors in the H-bridge circuit, thereby achieving forward, reverse, and stop control of the motor. This circuit structure has broad application prospects in the field of motor drives.

[0043] Furthermore, the H-bridge circuit also includes a filter capacitor C2, one end of which is connected to the collector of the second P-type transistor Q3, and the other end is connected to the collector of the first P-type transistor Q2.

[0044] When the MCU turns on Q3 and Q5 via the drive signal terminal, current flows from the +3.3V power supply terminal through Q3, into the motor, then out of the motor, and back to ground via Q5. The filter capacitor C2 absorbs and releases current during this process, reducing voltage fluctuations and making the motor rotate more smoothly.

[0045] When the MCU turns on Q2 and Q4 via the drive signal, current flows from the +3.3V power supply terminal through Q2, through the motor to Q4, and then back to ground from the emitter of Q4. The filter capacitor C2 also plays a role in reducing voltage fluctuations and suppressing noise during this process.

[0046] When all transistors are turned off, the motor stops rotating. During this process, the filter capacitor C2 releases its stored electrical energy to provide a short-term sustaining current for the motor, reducing voltage spikes during shutdown.

[0047] In the H-bridge circuit, the filter capacitor C2 is connected across the motor terminals. It absorbs and releases current to reduce voltage fluctuations, suppress noise, provide instantaneous power, and protect the transistors. Working in conjunction with the transistors, current-limiting resistors, and other components in the H-bridge circuit, it achieves precise control and smooth operation of the motor. This circuit structure has broad application prospects in motor drive fields, especially in applications requiring high precision, high stability, and low noise.

[0048] Furthermore, the H-bridge circuit also includes a first diode D2 and a second diode D3, wherein the cathode of the first diode D2 is connected to the collector of the first N-type transistor Q4, and the anode of the first diode D2 is grounded; the cathode of the second diode D3 is connected to the collector of the second N-type transistor Q5, and the anode of the second diode D3 is grounded.

[0049] When the MCU turns on Q3 and Q5 via the drive signal, current flows from the +3.3V power supply terminal through Q3, into the motor, then out of the motor, and back to ground via Q5. During this process, freewheeling diodes D2 and D3 are in reverse cutoff, not affecting the forward rotation of the motor. When the MCU turns on Q2 and Q4 via the drive signal, current flows from the +3.3V power supply terminal through Q2, through the motor to Q4, and then back to ground from the emitter of Q4. During this process, freewheeling diode D2 provides a reverse current conduction path for the motor. When the motor generates a back electromotive force due to inertia, D2 conducts, protecting Q4 from damage. Similarly, when the motor switches from forward to reverse rotation, freewheeling diode D3 plays the same role, protecting Q5 from damage. When all transistors are off, the motor stops rotating. At this time, freewheeling diodes D2 and D3 provide a conduction path for the back electromotive force provided by the motor, preventing the transistors from being damaged by the back electromotive force. In summary, the freewheeling diodes D2 and D3 in the H-bridge circuit are connected in parallel between the collector of the N-type transistor and ground. They function by handling the back electromotive force, protecting the transistor, improving motor operating efficiency, and reducing electromagnetic interference. Working in conjunction with other components in the H-bridge circuit, they achieve precise control and smooth operation of the motor. This circuit structure has broad application prospects in the field of motor drives, especially in applications requiring high precision, high stability, and high reliability.

[0050] Furthermore, it also includes connector JP2, in which pins 2 and 3 are connected to the positive and negative terminals of the motor respectively, while pin 1 is connected to the +3.3V power supply terminal and pin 4 is grounded.

[0051] When the MCU controls the transistors in the H-bridge circuit through the drive signal terminal, current flows into or out of the motor through pins 2 and 3 of connector JP2, thereby realizing the forward rotation, reverse rotation and stop control of the motor.

[0052] Connector JP2 ensures a stable power supply to the motor and protects against interference and noise from affecting the motor and circuitry through grounding protection. The introduction of connector JP2 makes the connection between the motor and external circuitry more flexible and reliable. When it is necessary to replace the motor or perform circuit maintenance, simply plug and unplug the connector; there is no need to resolder or change the circuit layout.

[0053] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A motor stall protection circuit based on parallel sampling resistors, characterized in that, include: The motor drive module, including an H-bridge circuit, is used to control the forward and reverse rotation and start / stop of a DC motor. The current sampling module consists of a first sampling resistor (R9) and a second sampling resistor (R91) connected in parallel. The first sampling resistor (R9) and the second sampling resistor (R91) are connected in series between the motor drive module and ground to convert the motor current into a sampling voltage. The filtering module includes an inductor (L2) and a first capacitor (C3). One end of the inductor (L2) is connected to the parallel node of the first sampling resistor (R9) and the second sampling resistor (R91), and the other end is grounded through the first capacitor (C3). The control module, connected to the output of the filtering module, includes an MCU, which is used to periodically acquire the filtered sample voltage and convert it into a corresponding current value; Meanwhile, the MCU compares the current value with a preset reference current threshold; when the current value is detected to continuously exceed the reference current threshold for a preset duration, the MCU controls the motor drive module to cut off the power supply to the motor.

2. The motor stall protection circuit based on parallel sampling resistors according to claim 1, characterized in that, The resistance values ​​of the first sampling resistor (R9) and the second sampling resistor (R91) range from 1.1Ω to 1.6Ω, and their equivalent resistance range after being connected in parallel is 0.55Ω to 0.8Ω.

3. The motor stall protection circuit based on parallel sampling resistors according to claim 1, characterized in that, The H-bridge circuit includes a first P-type transistor (Q2), a first N-type transistor (Q4), a second P-type transistor (Q3), and a second N-type transistor (Q5); The first P-type transistor (Q2) and the first N-type transistor (Q4) are connected in series to form a forward rotation bridge arm. The emitter of Q2 is connected to the +3.3V power supply terminal. The collectors of the first P-type transistor (Q2) and the first N-type transistor (Q4) are respectively connected to the positive and negative terminals of the motor. The emitter of the first N-type transistor (Q4) is grounded. The second P-type transistor (Q3) and the second N-type transistor (Q5) are connected in series to form an inverting bridge arm. The emitter of the second P-type transistor (Q3) is connected to the +3.3V power supply terminal, and the collectors of the second P-type transistor (Q3) and the second N-type transistor (Q5) are connected to the positive and negative terminals of the motor, respectively. The emitter of the second N-type transistor (Q5) is grounded.

4. A motor stall protection circuit based on a parallel sampling resistor according to claim 3, characterized in that, The base of the first P-type transistor (Q2) is connected to the first drive signal terminal (MODRV C) of the MCU through the first current-limiting resistor (R5); the base of the first N-type transistor (Q4) is connected to the third drive signal terminal (MODRV D) of the MCU through the second current-limiting resistor (R7); the base of the second P-type transistor (Q3) is connected to the second drive signal terminal (MODRV A) of the MCU through the third current-limiting resistor (R6); and the base of the second N-type transistor (Q5) is connected to the fourth drive signal terminal (MODRV B) of the MCU through the fourth current-limiting resistor (R8).

5. A motor stall protection circuit based on a parallel sampling resistor according to claim 4, characterized in that, The H-bridge circuit also includes a filter capacitor (C2). One end of the filter capacitor (C2) is connected to the collector of the second P-type transistor (Q3), and the other end is connected to the collector of the first P-type transistor (Q2). The two ends of the filter capacitor (C2) are connected to the positive and negative ends of the motor, respectively.

6. A motor stall protection circuit based on a parallel sampling resistor according to claim 5, characterized in that, The H-bridge circuit also includes a first diode (D2) and a second diode (D3), wherein the cathode of the first diode (D2) is connected to the collector of the first N-type transistor (Q4), and the anode of the first diode (D2) is grounded; the cathode of the second diode (D3) is connected to the collector of the second N-type transistor (Q5), and the anode of the second diode (D3) is grounded.

7. A motor stall protection circuit based on a parallel sampling resistor according to claim 6, characterized in that, It also includes a connector (JP2), in which pins 2 and 3 are connected to the positive and negative terminals of the motor respectively, while pin 1 is connected to the +3.3V power supply terminal and pin 4 is grounded.

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