A trigger control circuit based on single IO port to realize power management and direction identification

Abstract

The utility model is suitable for electric tool technical field provides a kind of trigger control circuit based on single IO mouth realizes power management and direction identification, including MCU, voltage division network, triode Q3, trigger switch and mains control module, the MCU built-in internal pull-up resistance R6, and is equipped with an IO mouth with power enable control and trigger direction identification function;In the utility model, by the hardware structure of "single IO mouth+ voltage division network (R6, R10, R12, R11 )+Q3", the "power enable control" and "trigger state detection" function of traditional double IO mouth are integrated, without extra occupying MCU IO mouth resource, for the low-cost MCU of pin shortage, can avoid the problem of needing to replace high-cost MCU due to IO mouth shortage, directly reduce hardware cost, while simplifying circuit wiring;System reliability is improved;Simplify control logic.

Description

Technical Field

[0001] This utility model belongs to the field of power tool technology, and in particular relates to a trigger control circuit that realizes power management and direction recognition based on a single IO port. Background Technology

[0002] The problem of wasted I / O resources: In existing power tools, detecting trigger direction (or status) and controlling main power enable require two independent I / O ports from the MCU. For low-cost MCUs with a limited number of pins, the extra I / O ports will lead to resource shortages, which not only increases the complexity of hardware design, but also requires the selection of MCU models with more pins, indirectly increasing production costs and hindering the lightweight and low-cost design of power tools; Low software reliability: The power-on of the existing system relies entirely on the MCU software logic. The software must first detect the trigger button action and then output a signal through another IO port to control the MOSFET to turn on to start the main power supply. This process increases the complexity of the software initialization process and has a response delay. If the program malfunctions, such as "running away" or initialization failure, it will directly cause the system to fail to start, have weak anti-interference ability, and affect the stability of the power tool's use. Therefore, a trigger control circuit based on a single I / O port to implement power management and direction recognition is needed to solve the above problems. Utility Model Content

[0003] The purpose of this utility model embodiment is to provide a trigger control circuit that realizes power management and direction recognition based on a single IO port, so as to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, this utility model provides the following technical solution: A trigger control circuit based on a single I / O port for power management and direction recognition includes an MCU, a voltage divider network, a transistor Q3, a trigger switch, and a main power control module. The MCU has a built-in internal pull-up resistor R6 and an IO port that combines power enable control and trigger direction recognition. One end of R6 is connected to the power supply terminal of the MCU, and the other end is connected to the IO port; The voltage divider network consists of resistors R10, R12, and R11. The IO port is connected to GND in sequence through R10 and R12. One end of R11 is connected to the node between R10 and R12, and the other end is connected to the base of Q3. The emitter of Q3 is connected to GND, and the collector is connected to the trigger switch; The trigger switch is also connected to the signal input terminal of the main power control module. The enable terminal of the main power control module is connected to the IO port. The main power is controlled by outputting a signal through the IO port, and the trigger direction is identified by detecting the voltage change of the voltage divider network through the IO port. By integrating "power enable" and "direction recognition" functions through a single I / O port, no additional I / O ports are required, making it compatible with low-cost MCUs and solving the problem of wasted I / O resources in existing solutions; the hardware structure has a high degree of integration, reducing the number of external components and lowering the circuit size and cost.

[0005] In a further technical solution, the MCU is applied to power tools, which include at least one of electric screwdrivers, electric drills, electric hammers, angle grinders, and jigsaws; Clearly define the target application scenario of the circuit to ensure that the circuit design aligns with the core requirements of power tools: "portable and requiring trigger control for start / stop / speed," thereby avoiding functional redundancy in general-purpose circuits and improving adaptability.

[0006] In a further technical solution, the resistance of resistor R10 is 2KΩ, the resistance of R12 is 1MΩ, and the resistance of R11 is 1KΩ. The main power control module includes a MOSFET Q1, a transistor Q2, and a resistor R2. The model of Q1 is AO3401, the model of Q2 is MMBT4401, and the resistance of R2 is 2KΩ. Resistors with specific resistance values ​​can precisely adjust the output voltage of the voltage divider network, ensuring that the I / O port can stably identify the trigger direction; specified models of MOSFETs and transistors are compatible with the voltage range of power tools (such as +5V control voltage, HVIN main power supply), avoiding damage to components due to parameter mismatch and improving circuit stability.

[0007] In a further technical solution, the transistor Q3 is model MMBT4401LT1G; This type of transistor features low on-state voltage and high switching speed, enabling it to quickly respond to voltage changes in the voltage divider network, ensuring real-time trigger direction recognition and avoiding misjudgment of direction due to transistor response delay.

[0008] In a further technical solution, in the main power control module, the base of Q2 is connected to the trigger switch through resistor R8 (resistance value 1KΩ), the emitter of Q2 is connected to GND, and the collector is connected to the gate of Q1. The source of Q1 is connected to the main power input terminal HVIN, and the drain is connected to the load of the power tool. One end of R2 is connected to the gate of Q1, and the other end is connected to HVIN.

[0009] Further technical solutions also include the SH1.0-8P interface, whose pins correspond to HVIN, +5V, GND, KEYON (connected to the trigger switch), SPEED (speed signal terminal), APEN / DIR (connected to the IO port), TSPEEDI (speed detection terminal) and no pin respectively; The standardized interface design facilitates the connection of the circuit with other modules of power tools (such as speed adjustment modules and display modules), reducing assembly difficulty, while the empty pins reserve expansion space to improve the scalability of the circuit.

[0010] A further technical solution is that when the voltage detected by the IO port is lower than the low-level recognition voltage of the MCU, the corresponding trigger moves in the first direction; When the voltage detected by the I / O port is higher than the MCU's high-level recognition voltage, the trigger moves in the second direction. When the main power is turned off, the MCU controls the I / O port to output a low level, causing the main power control module to cut off the main power.

[0011] Compared with the prior art, the beneficial effects of this utility model are: This invention saves MCU resources: By using a hardware structure of "single IO port + voltage divider network (R6, R10, R12, R11) + Q3", the "power enable control" and "trigger status detection" functions of the traditional dual IO port are integrated without occupying additional MCU IO port resources. For low-cost MCUs with limited pins, this can avoid the problem of having to replace high-cost MCUs due to insufficient IO ports, directly reducing hardware costs and simplifying circuit wiring. This invention improves system reliability: the power-on link relies on the voltage divider network and the hardware logic of Q3, without the need for MCU software initialization. The voltage divider network automatically adjusts the voltage through R6, R10, and R12 to turn on Q3. After the trigger is closed, it directly triggers the main power control module to start, avoiding system startup failures due to program crashes or initialization failures. The hardware response speed is faster than the software, reducing signal delay, and it has strong anti-electromagnetic interference capabilities, thus improving the stability of power tools. This invention simplifies control logic: the main power supply can be turned off simply by the MCU controlling the IO port to output a low level, which will cut off the main power supply through the main power supply control module, without the need for complex software timing control; the trigger direction is directly identified by detecting the voltage divider voltage through the IO port, without the need for additional software algorithm processing, which simplifies the software design difficulty and reduces the development cycle and maintenance cost.

[0012] To more clearly illustrate the structural features and effects of this utility model, the following detailed description of this utility model is provided in conjunction with the accompanying drawings and specific embodiments. Attached Figure Description

[0013] Figure 1This is a schematic diagram of the overall structure of this utility model; Figure 2 This is a schematic diagram of the wake-up circuit of this utility model; Figure 3 This is a schematic diagram of the trigger switch circuit of this utility model. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0015] The specific implementation of this utility model will be described in detail below with reference to specific embodiments. Example

[0016] like Figure 1-3 As shown, this utility model embodiment provides a trigger control circuit based on a single I / O port for power management and direction recognition, including an MCU (built-in R6), a voltage divider network (R10=2KΩ, R12=1MΩ, R11=1KΩ), Q3 (MMBT4401LT1G), a trigger switch, a main power control module (Q1=AO3401, Q2=MMBT4401, R2=2KΩ, R8=1KΩ) and an SH1.0-8P interface; R6 connects one end to the MCU's +5V power supply and the other end to the IO port (APEN / DIR). The IO port is connected to R12 via R10, R12 is connected to GND, one end of R11 is connected to the node of R10 and R12, and the other end is connected to the base of Q3; the emitter of Q3 is connected to GND, and the collector is connected to the trigger switch. The trigger switch is connected to the KEYON terminal, and the KEYON terminal is connected to the base of Q2 via R8; The emitter of Q2 is connected to GND, and the collector is connected to the gate of Q1. Q1 has its source connected to HVIN and its drain connected to the power tool load. R2 is connected to the gate of Q1 at one end and to HVIN at the other end; pin 6 of the SH1.0-8P interface is connected to the IO port, and the remaining pins are connected according to the labels.

[0017] In this embodiment, the circuit is adapted to an electric screwdriver (operating voltage: HVIN=12V, control voltage=+5V). The voltage divider network forms a stable voltage divider through R6 (pull-up), R10, and R12. When the trigger is not pressed, the IO port is pulled up to a high level (approximately 5V) through R6, and the base of Q3 receives current through R11, with the collector potential approximately GND. When the trigger is pressed in the forward direction, the trigger switch is connected to the +3V voltage divider terminal, the collector potential of Q3 rises to 3V, the voltage at the R10 and R12 nodes decreases, and the IO port voltage drops to 0.6V (below the MCU's low-level recognition voltage of 1V). The MCU recognizes the forward direction, and at the same time, the KEYON terminal receives a 3V signal, Q2 turns on, the gate potential of Q1 drops to 0V, Q1 turns on, and HVIN supplies power to the load. When the trigger is pressed in the reverse direction, the trigger switch is connected to the +4.5V voltage divider terminal, the collector potential of Q3 rises to 4.5V, the voltage at the R10 and R12 nodes rises, and the I / O port voltage rises to 3.2V (higher than the MCU's high-level recognition voltage of 2.8V). The MCU recognizes the reverse direction, and the main power supply is also turned on. When powered off, the I / O port outputs a low level, Q3, Q2, and Q1 are all turned off, and the main power supply is disconnected. This embodiment features high component parameter matching, 100% direction recognition accuracy, and a main power supply response time of <10ms, making it suitable for electric screwdrivers with high control precision requirements. Example

[0018] The difference between this embodiment and embodiment 1 is that the resistance value of R10 is adjusted to 1KΩ, the resistance value of R12 is adjusted to 800KΩ, and the MCU is replaced with a model with a low-level recognition voltage of 0.8V and a high-level recognition voltage of 2.5V. The other component models and connection relationships are the same as in embodiment 1.

[0019] In this embodiment, the circuit is adapted to an angle grinder (operating voltage: HVIN=24V, control voltage=+5V). The adjusted voltage divider network can match the level threshold of the new MCU: when the trigger is pressed in the forward direction, the IO port voltage drops to 0.7V (below 0.8V), and rises to 2.6V (above 2.5V) when pressed in the reverse direction, ensuring no error in direction recognition. At the same time, reducing the resistance of R10 can increase the current of the voltage divider network, avoiding voltage fluctuations caused by the large load current of the angle grinder. Q1 (AO3401) of the main power control module can withstand 24VHVIN voltage without the risk of overvoltage damage. In actual testing, the circuit can still work stably in the high-frequency vibration environment of the angle grinder, and its anti-interference capability meets industrial-grade requirements, solving the problem of easy misjudgment by traditional circuits in vibration environments. Example

[0020] The difference between this embodiment and embodiment 2 is that a diode D1 (model 1N4001, with the anode connected to the drain of Q1 and the cathode connected to the load) is added to the main power control module, and pin 5 (SPEED terminal) of the SH1.0-8P interface is changed to connect to the speed feedback pin of the MCU. The rest of the structure is the same as that of embodiment 2.

[0021] In this embodiment, the circuit is adapted to the electric hammer (which requires speed feedback and reverse voltage protection): the added D1 can prevent the reverse voltage generated when the electric hammer is under load from impacting Q1, avoiding Q1 breakdown and extending the service life of the components (D1 can withstand 50V reverse voltage during testing, which meets the requirements of the electric hammer). After the SPEED terminal is connected to the MCU speed feedback pin, the MCU can control the power supply through the IO port while obtaining the real-time speed of the electric hammer, realizing the integration of "power control + direction recognition + speed adjustment". In actual use, the speed adjustment response time of the electric hammer is <20ms and the power off time is <5ms. It maintains the core advantage of a single I / O port while expanding its functions to meet the needs of complex power tools.

[0022] Working principle and usage process of this utility model: Standby Phase: After the circuit is powered on, before the MCU starts, the I / O port is pulled up to +5V high level through the built-in R6; the voltage divider network starts working: the high level of R6 is divided by R10, generating approximately 0.025V at the node of R10 and R12 (R10=2KΩ, R12=1MΩ, voltage divider formula: Vnode=5V×R12 / (R10+R12)≈5V×1M / (2K+1M)≈4.99V). After the pull-up of R6, the I / O port... The high level is transmitted to R12 via R10, and R11 leads the node voltage to the base of Q3, causing Q3 to conduct (Q3 conduction voltage is about 0.7V, and the node voltage must meet the base current of Q3). After Q3 conducts, the collector potential is approximately GND. At this time, the trigger switch is off, there is no signal at the KEYON terminal of the main power control module, Q2 is off, and Q1 (MOS transistor) is also off because there is no conduction signal at its gate. The HVIN main power supply does not supply power to the load, and the circuit is in a low-power standby state. Trigger triggering and direction recognition phase: When the user presses the trigger switch, the external pressure terminal connected to the trigger switch varies depending on the direction of the press. If the trigger is pressed in the first direction (e.g., forward rotation), the trigger switch is connected to the low potential voltage divider terminal (e.g., +1V). The collector of Q3 receives a +1V voltage through the trigger switch, causing the voltage at the R10 and R12 nodes to decrease. The voltage transmitted to the base of Q3 through R11 decreases accordingly, weakening the conduction of Q3. The voltage detected by the IO port drops below the MCU's low-level recognition voltage (e.g., 0.6V). The MCU recognizes the trigger direction as forward rotation through the IO port. If pressed in the second direction (e.g., reverse), the trigger switch is connected to the high potential voltage divider (e.g., +4V), the collector of Q3 receives a +4V voltage, the voltage at the R10 and R12 nodes rises, and the voltage detected by the IO port rises above the MCU's high-level recognition voltage (e.g., 3.2V), and the MCU recognizes that the trigger direction is reverse. Power control phase: When the trigger switch is closed, the KEYON terminal receives a voltage signal (e.g., +1V for forward rotation, +4V for reverse rotation). This signal is current-limited by R8 and then transmitted to the base of Q2, turning Q2 on. After Q2 is turned on, its collector potential drops to GND, and the gate potential of Q1 decreases accordingly (Q1 is an N-channel MOSFET, which turns on when the gate voltage is lower than the source voltage). Q1 turns on, and the HVIN main power supply flows to the load through Q1, starting the power tool. The MCU can output corresponding control signals through the IO port according to the detected trigger direction, and cooperate with the load drive module to realize forward / reverse operation. Shutdown phase: When the user releases the trigger switch or needs to actively turn off the power, the MCU controls the IO port to output a low level; the low level of the IO port causes the node voltage of the voltage divider network to drop to 0V, and Q3 is turned off; at the same time, the low level signal of the IO port is transmitted to the main power control module, causing Q2 to lose its base signal and turn off, the gate potential of Q1 rises back to the HVIN voltage, Q1 is turned off, the HVIN main power supply stops supplying power to the load, and the circuit returns to the standby state; Throughout the entire operation, the core logic for power-on relies on the voltage divider network and the hardware structure of Q3, without the need for MCU software initialization, thus avoiding startup failures caused by software malfunctions. Furthermore, it completes "direction recognition" and "power control" through only one IO port, completely solving the resource waste and logic complexity problems of traditional dual IO port solutions. At the same time, the hardware structure is stable, has strong anti-interference capabilities, and is suitable for the working conditions of various power tools.

[0023] The circuits, electronic components, and modules involved are all existing technologies, which can be fully implemented by those skilled in the art, and need not be elaborated upon. The content protected by this utility model does not involve any improvement to the software and methods.

[0024] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A trigger control circuit based on a single I / O port for power management and direction recognition, comprising an MCU, a voltage divider network, a transistor Q3, a trigger switch, and a main power control module, characterized in that: The MCU has a built-in internal pull-up resistor R6 and an IO port that combines power enable control and trigger direction recognition. One end of R6 is connected to the power supply terminal of the MCU, and the other end is connected to the IO port; The voltage divider network consists of resistors R10, R12, and R11. The IO port is connected to GND in sequence through R10 and R12. One end of R11 is connected to the node between R10 and R12, and the other end is connected to the base of Q3. The emitter of Q3 is connected to GND, and the collector is connected to the trigger switch; The trigger switch is also connected to the signal input terminal of the main power control module. The enable terminal of the main power control module is connected to the I / O port. The main power supply is controlled by outputting a signal through the I / O port, and the trigger direction is identified by detecting the voltage change of the voltage divider network through the I / O port.

2. The trigger control circuit for power management and direction recognition based on a single I / O port as described in claim 1, characterized in that: The MCU is applied to power tools, which include at least one of electric screwdrivers, electric drills, electric hammers, angle grinders, and jigsaws.

3. The trigger control circuit for power management and direction recognition based on a single I / O port as described in claim 1, characterized in that: The resistance of resistor R10 is 2KΩ, the resistance of R12 is 1MΩ, and the resistance of R11 is 1KΩ. The main power control module includes a MOSFET Q1, a transistor Q2, and a resistor R2. The model of Q1 is AO3401, the model of Q2 is MMBT4401, and the resistance of R2 is 2KΩ.

4. The trigger control circuit for power management and direction recognition based on a single I / O port as described in claim 1, characterized in that: The transistor Q3 is model MMBT4401LT1G.

5. The trigger control circuit for power management and direction recognition based on a single I / O port as described in claim 1, characterized in that: In the main power control module, the base of Q2 is connected to the trigger switch through resistor R8, the emitter of Q2 is connected to GND, and the collector is connected to the gate of Q1. The source of Q1 is connected to the main power input terminal HVIN, and the drain is connected to the load of the power tool. One end of R2 is connected to the gate of Q1, and the other end is connected to HVIN.

6. The trigger control circuit for power management and direction recognition based on a single I / O port according to claim 1, characterized in that: It also includes an SH1.0-8P interface, whose pins correspond to HVIN, +5V, GND, KEYON, SPEED, APEN / DIR, TSPEEDI, and no pin, respectively.

7. The trigger control circuit for power management and direction recognition based on a single I / O port according to claim 1, characterized in that: When the voltage detected by the IO port is lower than the MCU's low-level recognition voltage, the corresponding trigger moves in the first direction; When the voltage detected by the I / O port is higher than the MCU's high-level recognition voltage, the trigger moves in the second direction. When the main power is turned off, the MCU controls the I / O port to output a low level, causing the main power control module to cut off the main power.

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