CN106095040A - A kind of key control circuit and electronic product - Google Patents

Abstract

The invention discloses a button control circuit and an electronic product. The circuit includes a DC power supply, a button, a power management chip, a main control chip, and a reset circuit; one end of the button is connected to the DC power supply, and the other end is connected to the enabling end of the power management chip. ;The power management chip supplies power to the main control chip; the main control chip is connected to the enabling end of the power management chip, and the other end of the button is connected to the main control chip; the reset circuit includes a charging resistor, a charging capacitor, and a switch tube; the DC power supply is charged through the button connection One end of the resistor and the other end of the charging resistor are grounded through the charging capacitor; the connection node between the charging capacitor and the charging resistor is connected to the control terminal of the switching tube, one end of the switching path of the switching tube is grounded, and the other end of the switching path of the switching tube is connected to the main control chip the reset pin, and connect the DC power supply through a current limiting resistor. The present invention realizes the functions of starting, shutting down and resetting the main control chip through a button, which is convenient for operation and low in cost.

Description

A key control circuit and electronic product

technical field

The invention belongs to the technical field of hardware circuits, and in particular relates to a key control circuit and electronic products designed using the key control circuit.

Background technique

There are various forms of virtual reality helmets on the market, and the forms of design also have their own characteristics.

At present, virtual reality helmets are designed with more buttons in order to realize the power-on, power-off and reset functions, resulting in high cost.

Contents of the invention

The invention provides a key control circuit, which can realize the functions of starting, shutting down and resetting through one key, thereby reducing the cost.

In order to solve the above-mentioned technical problems, the present invention adopts the following technical solutions to achieve:

A button control circuit, including a DC power supply, a button, a power management chip, a main control chip, and a reset circuit; one end of the button is connected to the DC power supply, and the other end is connected to the enabling end of the power management chip; the power management chip power supply for the main control chip; the main control chip is connected to the enabling end of the power management chip, and the other end of the button is connected to the main control chip; the reset circuit includes a charging resistor, a charging capacitor, and a switch tube; the DC power supply Connect one end of the charging resistor through a button, and the other end of the charging resistor is grounded through the charging capacitor; the connection node between the charging capacitor and the charging resistor is connected to the control terminal of the switching tube, and one end of the switching channel of the switching tube is grounded, and the The other end of the switching path of the switching tube is connected to the DC power supply through a current limiting resistor, and the other end of the switching path of the switching tube is connected to the reset pin of the main control chip.

Further, the key control circuit also includes a Bluetooth chip, and the main control chip controls the operation of the Bluetooth chip.

Still further, the power management chip is an LDO chip.

Still further, the button is connected to the enabling end of the power management chip through the first diode, the main control chip is connected to the enabling end of the power management chip through the second diode, and the cathodes of the two diodes are connected .

Furthermore, the enabling end of the power management chip is grounded through a pull-down resistor, and the enabling end of the power management chip is grounded through a capacitor.

Preferably, the switch tube is an NMOS tube, the gate of the NMOS tube is connected to the connection node between the charging capacitor and the charging resistor, the source of the NMOS tube is grounded, and the drain of the NMOS tube passes through the limiting The flow resistor is connected to the DC power supply, and the drain of the NMOS transistor is connected to the reset pin of the main control chip.

Preferably, the switching tube is an NPN transistor, the base of the NPN transistor is connected to the connection node between the charging capacitor and the charging resistor, the emitter of the NPN transistor is grounded, and the collector of the NPN transistor passes through the limiting The flow resistor is connected to the DC power supply, and the collector of the NPN transistor is connected to the reset pin of the main control chip.

Further, the key control circuit further includes an electrostatic protection circuit, and the connection node between the key and the charging resistor is grounded through the electrostatic protection circuit.

Still further, the reset circuit further includes a discharge circuit, the discharge circuit includes a discharge diode and a discharge resistor, the anode of the discharge diode is connected to the connection node between the charging capacitor and the charging resistor, and the cathode of the diode passes through the The discharge resistor is grounded.

Based on the structural design of the above key control circuit, the present invention also proposes an electronic product designed using the key control circuit, including the key control circuit. The key control circuit includes a DC power supply, a key, a power management chip, Main control chip and reset circuit; one end of the button is connected to the DC power supply, and the other end is connected to the enabling end of the power management chip; the power management chip supplies power to the main control chip; the connection between the main control chip and the power management chip The enable end is connected, the other end of the button is connected to the main control chip; the reset circuit includes a charging resistor, a charging capacitor, and a switch tube; the DC power supply is connected to one end of the charging resistor through a button, and the other end of the charging resistor is connected to the The charging capacitor is grounded; the connection node between the charging capacitor and the charging resistor is connected to the control terminal of the switch tube, one end of the switch path of the switch tube is grounded, and the other end of the switch path of the switch tube is connected to the DC through a current limiting resistor. The other end of the switching path of the switching tube is connected to the reset pin of the main control chip.

Compared with the prior art, the advantages and positive effects of the present invention are: the button control circuit and electronic products of the present invention realize the power-on, shutdown and reset functions of the main control chip through a button, and the control method is relatively simple, which is convenient for users to operate , easy to use, and improve user experience; due to the small number of buttons, the entire circuit uses fewer components, the circuit structure is relatively simple, easy to implement, low cost, has strong competitiveness, and is easy to popularize and apply.

Other features and advantages of the present invention will become more apparent after reading the detailed description of the embodiments of the present invention in conjunction with the accompanying drawings.

Description of drawings

Fig. 1 is the circuit structural diagram of an embodiment of the button control circuit proposed by the present invention;

Fig. 2 is the circuit schematic diagram of an embodiment of the button control circuit proposed by the present invention;

FIG. 3 is a circuit schematic diagram of another embodiment of the key control circuit proposed by the present invention.

detailed description

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings.

The button control circuit of this embodiment mainly includes a DC power supply PWR, a button U1, a power management chip U7, a main control chip MCU, a reset circuit, etc., as shown in Figures 1 and 2; one end of the button U1 is connected to the DC power supply PWR, and the other end Connect the enabling terminal EN of the power management chip U7; the power output terminal VOUT of the power management chip U7 is connected to the main control chip, the output power VCC supplies power to the main control chip MCU, and the main control chip MCU and the enabling terminal EN of the power management chip U7 Connection; the other end of the button U1 is connected to the detection pin of the main control chip MCU, and the main control chip MCU detects the opening and closing state of the button U1; the reset circuit mainly includes the charging resistor R3, the charging capacitor C2, the switch tube Q5, etc., and the DC power supply PWR Connect one end of the charging resistor R3 through the button U1, the other end of the charging resistor R3 is connected to one end of the charging capacitor C2, the other end of the charging capacitor C2 is grounded, the connection node of the charging capacitor C2 and the charging resistor R3 is connected to the control terminal of the switch tube Q5, One end of the switching path of the switching tube Q5 is grounded, the other end of the switching path of the switching tube Q5 is connected to the DC power supply PWR through the current limiting resistor R4, and the other end of the switching path of the switching tube Q5 is connected to the reset pin of the main control chip, and the other end of the switching path of the switching tube Q5 is connected to the reset pin of the main control chip. The reset pin of the chip sends a reset signal.

When the main control chip is turned off, if you need to turn it on, press the button U1, and the high level provided by the DC power supply PWR is transmitted to the enable terminal EN of the power management chip U7 through the button U1, enabling the power management chip U7, power management When the chip U7 is running, the power supply output terminal VOUT outputs the power supply VCC to supply power to the main control chip MCU, and the main control chip MCU is powered on to run; after the main control chip MCU is powered on, it outputs a high level to the enable terminal EN of the power management chip U7; At this time, even if the button U1 is released, the enable terminal EN of the power management chip U7 can be guaranteed to be at a high level, so that the power management chip U7 can work normally, and the main control chip MCU can continue to supply power to realize the power-on function of the main control chip MCU.

After the main control chip is turned on, it detects the opening and closing state of the button U1 in real time by detecting the level of its detection pin.

After the main control chip is turned on, if the button U1 is in the off state, the control terminal of the switch tube Q5 is at a low level, and since the switch tube Q5 is turned on at a high level, the switch tube Q5 is turned off, and the switch path of the switch tube Q5 The other end of the pin is high level, at this time the reset pin of the main control chip is high level, and the main control chip works normally (no reset).

After the main control chip is turned on, if you need to turn it off, you can press and hold the button U1. When the button U1 is pressed again and the pressing time reaches the set shutdown time (such as 5 seconds), the potential of the detection pin of the main control chip jumps from low level to high level, and the high level signal lasts for a period of time ( reaches the set shutdown time), the main control chip outputs a low-level shutdown signal to the enable terminal EN of the power management chip U7 after the button U1 is released, the power management chip U7 turns off, stops outputting the power supply VCC, and the main control chip turns off. Electric shutdown, realize the shutdown function.

After the main control chip is turned on, if you need to reset, press the button U1, the DC power supply PWR will charge the charging capacitor C2 through the charging resistor R3, and the voltage at both ends of the charging capacitor C2 will gradually increase. When the conduction condition of the switch tube Q5 is met , the switching tube Q5 is turned on, the current provided by the DC power supply PWR flows into the ground through the current limiting resistor R4 and the switching path of the switching tube Q5, and the other end of the switching path of the switching tube Q5 is pulled to a low level, and resets the main control chip. The pin sends a low-level reset signal, the reset pin of the main control chip is pulled to low level, and the main control chip is reset to realize the reset function of the main control chip and prevent the software of the main control chip from running away.

By adjusting the values of the charging resistor R3 and the charging capacitor C2, the conduction time of the switch tube Q5 can be flexibly adjusted, thereby adjusting the hardware reset time, that is, the pressing time of the button U1. If the button U1 is pressed and closed for 10 seconds, the switch tube Q5 is turned on, and the main control chip is reset.

Of course, the reset time is adjusted by adjusting the values of the charging resistor R3 and the charging capacitor C2, so that the reset time is longer than the set shutdown time to avoid misoperation.

The key control circuit of this embodiment realizes the power-on, power-off and reset functions of the main control chip through a key U1. The circuit adopts fewer components, has a relatively simple circuit structure, is easy to realize, has low cost, has strong competitiveness, and is convenient for popularization and application.

A bluetooth chip BT is also arranged in the button control circuit, and the main control unit is connected with the bluetooth chip BT to control the operation of the bluetooth chip.

After the main control chip is turned on, click (or short press) the button U1, that is, the detection pin potential of the main control chip jumps from low level to high level, then the main control chip sends a pairing start signal to the Bluetooth chip through the serial port UART After receiving the signal, the Bluetooth chip starts the pairing function to realize the pairing between the Bluetooth chip and external devices, such as mobile phones and PADs.

For example, after the main control chip is powered on and the Bluetooth chip is paired with the mobile phone, if the mobile phone calls at this time, you can click the button U1, and the main control chip will send a control command to the Bluetooth chip after detecting the level change. The bluetooth chip connects to the phone and realizes the function of connecting to the phone.

By setting the bluetooth chip in the button control circuit, the function of the circuit is enriched, the application range of the circuit is expanded, and the market competitiveness is improved.

In this embodiment, the power management chip U7 is preferably an LDO chip, which has low power consumption and stable performance, and can provide the required power for the main control chip.

In order to ensure the correct flow of current, prevent backflow, and improve the stability and safety of the circuit, the button U1 is connected to the enable terminal EN of the power management chip U7 through the first diode D2, and the main control chip is connected through the second diode D3 It is connected with the enable end EN of the power management chip U7. That is, the cathodes of the first diode D2 and the second diode D3 are connected, and the connection point is connected to the enable terminal EN of the power management chip U7, the anode of the first diode D2 is connected to the key U1, and the second diode The anode of the tube D3 is connected to the main control unit; thereby preventing the electric energy output by the DC power supply PWR from being poured back into the main control chip and the electric energy output by the main control chip from being poured back into the DC power supply PWR.

The enable terminal EN of the power management chip U7 is grounded through the pull-down resistor R5, and keeps a low level when the enable terminal EN is not pulled high to ensure that the potential of the enable terminal EN is stable, avoid repeatedly turning on the power management chip U7, and ensure that the power management chip The state of U7 is stable.

The enable terminal EN of the power management chip U7 is grounded through the capacitor C79, and the capacitor C79 has a delay function. When the key U1 is pressed to start the main control chip, the power provided by the DC power supply PWR is transmitted to the enable terminal of the power management chip U7 through the key U1 and the first diode D2, and charges the capacitor C79, and the voltage at both ends of the capacitor C79 gradually rises High, enable the power management chip U7.

When the main control chip sends a low level to the enable terminal EN of the power management chip U7 due to accidental factors, the capacitor C79 is discharged through the pull-down resistor R5, the voltage at both ends of the capacitor C79 gradually decreases, and the voltage at the enable terminal EN gradually decreases. The chip U7 can also keep working normally for a period of time. During this period, the main control chip may resume sending high level to the enable terminal EN of the power management chip U7, so as to avoid the short-term low voltage output fluctuation of the main control chip. The power management chip U7 is turned off, which improves the stability of the power management chip U7 and ensures the power supply stability of the main control chip.

The switching tube Q5 is turned on at a high level. In this embodiment, the switching tube Q5 is preferably an NMOS tube. The gate of the NMOS tube is connected to the connection node between the charging capacitor C2 and the charging resistor R3, and the source of the NMOS tube is grounded. The drain of the NMOS transistor is connected to the DC power supply PWR through the current limiting resistor R4, and the drain of the NMOS transistor is connected to the reset pin of the main control chip, as shown in FIG. 3 .

As another preferred design scheme of this embodiment, the switch tube Q5 is selected as an NPN transistor, the base of the NPN transistor is connected to the connection node between the charging capacitor C2 and the charging resistor R3, the emitter of the NPN transistor is grounded, and the collector of the NPN transistor passes through The current limiting resistor R4 is connected to the DC power supply PWR, and the collector of the NPN transistor is connected to the reset pin of the main control chip.

The reset circuit of this embodiment charges the charging capacitor C2 through the charging resistor R3, and controls the on-off of the switch tube Q5 through the voltage at both ends of the charging capacitor C2, thereby controlling the level of the reset signal, and then controlling whether the main control chip is reset or not. The control method is relatively simple and easy to use; and a switch tube (NMOS tube or NPN transistor) is used, the circuit structure is simple, easy to implement, low cost, and reduces the cost of the reset circuit.

In order to release the charge on the charging capacitor C2, a discharge circuit is also provided in the button control circuit, and the charge on the charging capacitor C2 is released through the discharge circuit. The discharge circuit mainly includes a diode D1 and a discharge resistor R1. The anode of the diode D1 is connected to the connection node between the charging capacitor C2 and the charging resistor R3, and the cathode of the diode D1 is grounded through the discharge resistor R1.

After reset, release the button U1, discharge the charge in the charging capacitor C2 through the diode D1 and the discharge resistor R1; the voltage at both ends of the charging capacitor C2 gradually decreases, and the voltage at the control terminal of the switching tube Q5 gradually decreases. When the condition is on, the switch tube Q5 is turned off.

An electrostatic protection circuit is also provided in the key control circuit, and the connection node between the key U1 and the charging resistor R3 is grounded through the electrostatic protection circuit.

The electrostatic protection circuit is used for electrostatic protection to prevent electronic devices in the circuit from being damaged by static electricity, improve the stability of the entire circuit, prolong the service life of electronic devices, and reduce maintenance costs.

In this embodiment, the electrostatic protection circuit is preferably an ESD tube, that is, a double diode device with anodes connected in reverse series, which has a simple structure, is easy to implement, and has a low cost. Of course, the ESD protection circuit can also be built with other components, not limited to the above examples.

In order to filter out high-frequency clutter, a filter capacitor C1 is also set in the button control circuit, and the DC power supply PWR is grounded through the filter capacitor C1, thereby filtering out the high-frequency clutter output by the DC power supply and avoiding damage to other components in the reset circuit .

Based on the above design of the key control circuit, this embodiment also proposes an electronic product, including the key control circuit.

Electronic products are wearable electronic devices that need to be turned on, off, and hardware reset through a single button, such as virtual reality helmets.

By designing the button control circuit in the electronic product, the power-on, shutdown and reset functions of the main control chip can be realized by one button, which is convenient for users to operate and improves the user experience; due to the small number of designed buttons, not only makes The electronic product has a better appearance, and makes the circuit structure simpler and easier to implement, reduces the cost and improves the competitiveness of the electronic product.

Of course, the above descriptions are not intended to limit the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention shall also belong to protection scope of the present invention.

Claims (10)

1. A button control circuit, characterized in that: comprising a DC power supply, a button, a power management chip, a main control chip, and a reset circuit; One end of the button is connected to the DC power supply, and the other end is connected to the enabling end of the power management chip; the power management chip supplies power to the main control chip; the main control chip is connected to the enabling end of the power management chip, and the The other end of the button is connected to the main control chip; The reset circuit includes a charging resistor, a charging capacitor, and a switch tube; the DC power supply is connected to one end of the charging resistor through a button, and the other end of the charging resistor is grounded through the charging capacitor; the connection node between the charging capacitor and the charging resistor is connected to the switch The control end of the switch tube is connected, one end of the switch path of the switch tube is grounded, the other end of the switch path of the switch tube is connected to the DC power supply through a current limiting resistor, and the other end of the switch path of the switch tube is connected to the main control chip the reset pin. 2. The button control circuit according to claim 1, characterized in that: the button control circuit further includes a Bluetooth chip, and the main control chip controls the operation of the Bluetooth chip. 3. The button control circuit according to claim 1, wherein the power management chip is an LDO chip. 4. The button control circuit according to claim 1, characterized in that: the button is connected to the enable end of the power management chip through the first diode, and the main control chip is connected to the power management chip through the second diode. The enabling end of the chip is connected, and the cathodes of the two diodes are connected. 5 . The button control circuit according to claim 1 , wherein the enabling terminal of the power management chip is grounded through a pull-down resistor, and the enabling terminal of the power management chip is grounded through a capacitor. 6. The button control circuit according to claim 1, characterized in that: the switch tube is an NMOS tube, the gate of the NMOS tube is connected to the connection node between the charging capacitor and the charging resistor, and the source of the NMOS tube is The drain of the NMOS transistor is connected to the DC power supply through the current limiting resistor, and the drain of the NMOS transistor is connected to the reset pin of the main control chip. 7. The button control circuit according to claim 1, characterized in that: the switch tube is an NPN triode, the base of the NPN triode is connected to the connection node between the charging capacitor and the charging resistor, and the emission of the NPN triode The collector of the NPN transistor is connected to the DC power supply through the current limiting resistor, and the collector of the NPN transistor is connected to the reset pin of the main control chip. 8. The button control circuit according to claim 1, characterized in that: the button control circuit further comprises an electrostatic protection circuit, and the connection node between the button and the charging resistor is grounded through the electrostatic protection circuit. 9. The button control circuit according to claim 1, wherein the reset circuit further includes a discharge circuit, the discharge circuit includes a discharge diode and a discharge resistor, and the anode of the discharge diode is connected to the charging capacitor and the charging capacitor. The connection node of the resistor, the cathode of the diode is grounded through the discharge resistor. 10. An electronic product, characterized by comprising the button control circuit according to any one of claims 1 to 9.