360-degree RSSI (Received Signal Strength Indicator) test fixture
By designing a dial assembly and servo motor system for the 360° RSSI test fixture, the test product angle is automatically adjusted, solving the problems of test result deviation and low efficiency caused by manual adjustment in the existing technology, and achieving more efficient and accurate testing.
Patent Information
- Application Number
- CN202422536312.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-21
- Publication Date
- 2025-10-24
- Estimated Expiration
- 2034-10-21
AI Technical Summary
The existing 360° RSSI test method requires manual adjustment of the test product's placement angle, resulting in biased test results and low efficiency.
A 360° RSSI test fixture is designed, which includes a dial assembly, a servo motor, a control circuit, a voltage stabilization circuit, and a step-down circuit. The control circuit controls the rotation of the servo motor to automatically adjust the angle of the test product, and displays the angle information on the screen to reduce manual intervention.
It realizes automated testing without manual angle correction, improving the accuracy and efficiency of testing.
Smart Images
Figure CN223471099U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model belongs to test fixture technical field, concretely relates to a 360 RSSI test fixture for. BACKGROUND
[0002] At present, the main mode of 360 RSSI test is that the measured product and the development board are on the same straight line, the default interval is 1m, the distance from the ground is 1.5m, the test is placed horizontally, each 360 ° (the antenna position of the horizontally placed product and the direction of the dial pointer are consistent, and the antenna position of the vertically placed product and the direction of the dial pointer are on the same plane and perpendicular) is scanned and saved by the mobile phone software. Every 10 °, the disc is rotated by hand, the next angle test is carried out, the angle is corrected, until 360 ° is rotated to indicate that the test is completed, and the data is recorded to the radar chart to mark the test direction and the corresponding picture.
[0003] The existing 360 RSSI test mode needs to manually adjust the test product angle, after the 360 RSSI test mode is adjusted and placed, the position needs to be corrected, which is easy to cause the deviation of the test result due to the uncalibrated position, the test mode is complex to realize, needs to do more correction steps, and the test efficiency is low. CONTENT OF THE UTILITY MODEL
[0004] Therefore, the main purpose of the utility model is to provide a 360 RSSI test fixture.
[0005] To achieve the above purpose, the technical scheme of the utility model is as follows:
[0006] The utility model embodiment one provides a 360 RSSI test fixture, including dial assembly, shell assembly, servo motor, control circuit, voltage stabilizing circuit, voltage reducing circuit, the dial assembly is set up on the shell assembly, the servo motor is set up in the shell assembly, is used for driving the dial assembly rotation, the output of voltage stabilizing circuit is connected with the input of voltage reducing circuit, the output of voltage reducing circuit is connected with the input of control circuit, the control circuit is used for controlling servo motor rotation.
[0007] In the above scheme, the shell assembly includes a shell, a base, and the base is arranged at the bottom of the shell.
[0008] In the above scheme, the dial assembly includes a dial, a scale line, a guide rail, a disc and an indication label, the dial is arranged at the top of the shell, the scale line is arranged on the dial, the guide rail is installed on the dial, the disc is installed on the guide rail, and the indication label is arranged on the disc.
[0009] In the scheme, the servo motor is arranged in the shell and mounted on the base, and the rotor of the servo motor is connected with the center of the disc through the rotating shaft.
[0010] In the scheme, the voltage stabilizing circuit comprises a fuse, a thirteenth resistor, a slide rheostat, a first capacitor, a twenty-fourth resistor, a twenty-ninth resistor, a second inductor, a voltage stabilizing chip, a first inductor, a fifty-second capacitor, a fifty-third capacitor, a fifth capacitor, a sixteenth capacitor, an eighteenth capacitor, a third diode, the first end of the fuse is connected with the live wire of the power supply, the second end of the fuse is connected with the first end of the slide rheostat and the first end of the thirteenth resistor respectively, the second end of the thirteenth resistor is connected with the first end of the first capacitor, the first end of the twenty-fourth resistor and the first end of the second inductor respectively, the second end of the slide rheostat is connected with the zero line of the power supply, the second end of the first capacitor, the first end of the twenty-ninth resistor and the AC(N) end of the voltage stabilizing chip respectively, the second end of the twenty-fourth resistor is connected with the second end of the twenty-ninth resistor, the second end of the second inductor is connected with the AC(L) end of the voltage stabilizing chip, the +Vo end of the voltage stabilizing chip is connected with the first end of the fifth capacitor and the first end of the first inductor respectively, the second end of the first inductor is connected with the first end of the sixteenth capacitor, the first end of the eighteenth capacitor, the negative electrode of the second diode and the positive electrode of the third diode respectively, the second end of the fifth capacitor, the second end of the sixteenth capacitor, the second end of the eighteenth capacitor and the positive electrode of the second diode are grounded, the first end of the fifty-second capacitor is connected with the +V(CAP) end of the voltage stabilizing chip, the second end of the fifty-second capacitor is connected with the first end of the fifty-third capacitor and the -V(CAP) end of the voltage stabilizing chip respectively, and the second end of the fifty-third capacitor is connected with the -VO end of the voltage stabilizing chip and then grounded.
[0011] In the scheme, the voltage stabilizing circuit comprises a fuse, a thirteenth resistor, a slide rheostat, a first capacitor, a twenty-fourth resistor, a twenty-ninth resistor, a second inductor, a voltage stabilizing chip, a first inductor, a fifty-second capacitor, a fifty-third capacitor, a fifth capacitor, a sixteenth capacitor, an eighteenth capacitor, a third diode, the first end of the fuse is connected with the live wire of the power supply, the second end of the fuse is connected with the first end of the slide rheostat and the first end of the thirteenth resistor respectively, the second end of the thirteenth resistor is connected with the first end of the first capacitor, the first end of the twenty-fourth resistor and the first end of the second inductor respectively, the second end of the slide rheostat is connected with the zero line of the power supply, the second end of the first capacitor, the first end of the twenty-ninth resistor and the AC(N) end of the voltage stabilizing chip respectively, the second end of the twenty-fourth resistor is connected with the second end of the twenty-ninth resistor, the second end of the second inductor is connected with the AC(L) end of the voltage stabilizing chip, the +Vo end of the voltage stabilizing chip is connected with the first end of the fifth capacitor and the first end of the first inductor respectively, the second end of the first inductor is connected with the first end of the sixteenth capacitor, the first end of the eighteenth capacitor, the negative electrode of the second diode and the positive electrode of the third diode respectively, the second end of the fifth capacitor, the second end of the sixteenth capacitor, the second end of the eighteenth capacitor and the positive electrode of the second diode are grounded, the first end of the fifty-second capacitor is connected with the +V(CAP) end of the voltage stabilizing chip, the second end of the fifty-second capacitor is connected with the first end of the fifty-third capacitor and the -V(CAP) end of the voltage stabilizing chip respectively, and the second end of the fifty-third capacitor is connected with the -VO end of the voltage stabilizing chip and then grounded.
[0012] In the scheme, the control circuit includes a control chip, a motor driving circuit, a key circuit, a screen display circuit, the power input end V of the control chip is connected with the 3.3V power output end, the signal output end of the key circuit is connected with the input end of the control chip, the output end of the control chip is connected with the input end of the screen display circuit, the control chip is in communication connection with the motor driving circuit, and the motor driving circuit is connected with the servo motor.
[0013] In the scheme, the motor driving circuit includes a driving chip, a thirty-first resistor and a fifth light emitting diode, the MOTOR_CS end of the driving chip is connected with the P0.24 end of the control chip, the MOTOR_EN end of the driving chip is connected with the P0.23 end of the control chip, and the LED_OUT end of the driving chip is connected with the thirty-first resistor and the fifth light emitting diode in sequence and then grounded.
[0014] In the scheme, the screen display circuit includes a screen display interface, the SCL end of the screen display interface is connected with the P0.11 end of the control chip, and the SDA end of the screen display interface is connected with the P0.12 end of the control chip.
[0015] In the scheme, the key circuit includes a first key, a second key, a third key, a fourth key, a first resistor, a second resistor, a third resistor and a fourth resistor, the first end of the first resistor is connected with the P0.13 end of the control chip, the second end of the first resistor is connected with the first end of the first key, the first end of the second resistor is connected with the P0.14 end of the control chip, the second end of the second resistor is connected with the first end of the second key, the first end of the third resistor is connected with the P0.15 end of the control chip, the second end of the third resistor is connected with the first end of the third key, the first end of the fourth resistor is connected with the P0.16 end of the control chip, the second end of the fourth resistor is connected with the first end of the fourth key, and the second end of the first key is connected with the second end of the second key, the second end of the third key and the second end of the fourth key in sequence and then grounded.
[0016] Compared with the prior art, the servo motor is controlled to rotate through the control circuit, the current 360° RSSI test and manual adjustment problem are solved, the test product after adjustment needs not to be re-corrected, more accurate data are provided, the console is provided with adjustment keys and a screen display, the user can check the rotating angle of the dial through the screen, thereby angle adjustment is conducted, the 360° angle is randomly switched, manual angle adjustment is not needed, and test efficiency is effectively improved. BRIEF DESCRIPTION OF DRAWINGS
[0017] The drawings described herein are used to disclose further understanding of the utility model, constitute a part of the utility model, the illustrative embodiment of the utility model and its explanation are used to explain the utility model, and do not constitute undue limitation to the utility model. In the drawings,
[0018] Figure 1 A top view structural schematic diagram of a 360° RSSI test fixture is described for the utility model embodiment;
[0019] Figure 2 An exploded structural schematic diagram of a 360° RSSI test fixture is described for the utility model embodiment;
[0020] Figure 3 A structural block diagram of a control circuit is described for the utility model embodiment;
[0021] Figure 4 A structural schematic diagram of a voltage stabilizing circuit is described for the utility model embodiment;
[0022] Figure 5 A structural schematic diagram of a voltage reducing circuit is described for the utility model embodiment;
[0023] Figure 6 A structural schematic diagram of a control chip is described for the utility model embodiment;
[0024] Figure 7 A structural schematic diagram of a motor driving circuit is described for the utility model embodiment;
[0025] Figure 8 A structural schematic diagram of a screen display circuit is described for the utility model embodiment;
[0026] Figure 9 A structural schematic diagram of a key circuit is described for the utility model embodiment. DETAILED DESCRIPTION
[0027] In order to make the purpose, technical scheme and advantages of the utility model more clear and obvious, the utility model is further described in detail below by combining with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the utility model, and do not limit the utility model.
[0028] The same or similar reference numerals in the drawings of the embodiments correspond to the same or similar components; in the description of the utility model, it is understood that the terms "upper", "lower", "left", "right", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the utility model and simplifying the description, and therefore the terms describing the positional relationship in the drawings are only used for exemplary illustration, and cannot be understood as limiting the patent; for ordinary skilled persons in the art, the specific meanings of the above terms can be understood according to the specific circumstances.
[0029] It should be noted that in this document, the terms "comprise", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such a process, article or device. Without more limitations, the element defined by the sentence "comprises a" does not exclude the presence of another identical element in the process, article or device comprising the element.
[0030] As shown in Figures 1-9 Embodiment one of the utility model provides a kind of 360 ° RSSI test fixture, including dial assembly, shell assembly, servo motor 6, control circuit, voltage stabilizing circuit, voltage reducing circuit, the dial assembly is set on shell assembly, the servo motor 6 is set in shell assembly, for driving dial assembly rotation, the output of voltage stabilizing circuit is connected with the input of voltage reducing circuit, the output of voltage reducing circuit is connected with the input of control circuit, and the control circuit is used to control servo motor 6 rotation.
[0031] As shown in Figure 1 And Figure 2 The shell assembly includes shell 7, base 8, as shown in the drawings, the base 8 is set on the bottom of shell 7.
[0032] As shown in Figure 1 And Figure 2 The dial assembly includes dial 5, scale line 4, guide rail 3, disc 2, indicating label 1, as shown in the drawings, the dial 5 is set on the top of shell 7, the scale line 4 is set on dial 5, the guide rail 3 is installed on dial 5, the disc 2 is installed on guide rail 3, and the indicating label 1 is set on disc 2.
[0033] As shown in Figure 1 And Figure 2 The servo motor 6 is set in shell 7 and is installed on base 8, and the rotor of the servo motor 6 is connected with the center of disc 2 through shaft 9.
[0034] As Figure 3 and Figure 4 shown, the voltage stabilizing circuit includes a fuse F1, a thirteenth resistor R13, a slide rheostat MOV1, a first capacitor C1, a twenty-fourth resistor R24, a twenty-ninth resistor R29, a second inductor L2, a voltage stabilizing chip U1, a first inductor L1, a fifty-second capacitor C52, a fifty-third capacitor C53, a fifth capacitor C5, a sixteenth capacitor C16, an eighteenth capacitor C18, a third diode D3, the first end of the fuse F1 is connected with the live wire of the power supply, the second end of the fuse F1 is connected with the first end of the slide rheostat MOV1 and the first end of the thirteenth resistor R13 respectively, the second end of the thirteenth resistor R13 is connected with the first end of the first capacitor C1, the first end of the twenty-fourth resistor R24 and the first end of the second inductor L2 respectively, the second end of the slide rheostat MOV1 is connected with the zero line of the power supply, the second end of the first capacitor C1, the first end of the twenty-ninth resistor R29 and the AC(N) end of the voltage stabilizing chip U1 respectively, the second end of the twenty-fourth resistor R24 is connected with the second end of the twenty-ninth resistor R29, the second end of the second inductor L2 is connected with the AC(L) end of the voltage stabilizing chip U1, the +Vo end of the voltage stabilizing chip U1 is connected with the first end of the fifth capacitor C5 and the first end of the first inductor L1 respectively, the second end of the first inductor L1 is connected with the first end of the sixteenth capacitor C16, the first end of the eighteenth capacitor C18, the negative electrode of the second diode D2 and the positive electrode of the third diode D3 respectively, the second end of the fifth capacitor C5, the second end of the sixteenth capacitor C16, the second end of the eighteenth capacitor C18 and the positive electrode of the second diode D2 are all grounded, the first end of the fifty-second capacitor C52 is connected with the +V(CAP) end of the voltage stabilizing chip U1, the second end of the fifty-second capacitor C52 is connected with the first end of the fifty-third capacitor C53 and the -V(CAP) end of the voltage stabilizing chip U1 respectively, the second end of the fifty-third capacitor C53 is connected with the -VO end of the voltage stabilizing chip U1 and then grounded.
[0035] As Figure 3 , Figure 4 and Figure 5As shown in the figure, the voltage reduction circuit includes voltage reduction chip U3, forty-sixth capacitor C46, nineteenth capacitor C19, twenty-seventh capacitor C27, forty-fifth capacitor C45, 3.3V power output end, the VIN end of the voltage reduction chip U3 is connected with the CE end of the voltage reduction chip U3, the first end of the nineteenth capacitor C19, the first end of the forty-sixth capacitor C46 and the negative electrode of the second diode D2 respectively, the second end of the forty-sixth capacitor C46 is connected with the second end of the nineteenth capacitor C19 and the VSS end of the voltage reduction chip U3 and grounded, the VOUT end of the voltage reduction chip U3 is connected with the first end of the twenty-seventh capacitor C27, the first end of the forty-fifth capacitor C45 and the 3.3V power output end respectively, the second end of the twenty-seventh capacitor C27 and the second end of the forty-fifth capacitor C45 are grounded.
[0036] As shown in the figure, Figure 3 and Figure 6 As shown in the figure, the control circuit includes control chip MU1, motor drive circuit, key circuit, screen display circuit, the power input end VCC of the control chip MU1 is connected with the 3.3V power output end 3V3, the signal output end of the key circuit is connected with the input end of the control chip MU1, the output end of the control chip MU1 is connected with the input end of the screen display circuit, the control chip MU1 is connected with the motor drive circuit in communication, the motor drive circuit is connected with the servo motor 6.
[0037] As shown in the figure, Figure 3 , Figure 6 and Figure 7 As shown in the figure, the motor drive circuit includes driving chip U5, thirty-first resistor R31, fifth light emitting diode LED5, the MOTOR_CS end of the driving chip U5 is connected with the P0.24 end of the control chip MU1, the MOTOR_EN end of the driving chip U5 is connected with the P0.23 end of the control chip MU1, the LED_OUT end of the driving chip U5 is grounded after the thirty-first resistor R31 and the fifth light emitting diode LED5 are connected in series.
[0038] As shown in the figure, Figure 3 , Figure 6 and Figure 8 As shown in the figure, the screen display circuit includes screen display interface J2, the SCL end of the screen display interface J2 is connected with the P0.11 end of the control chip MU1, the SDA end of the screen display interface J2 is connected with the P0.12 end of the control chip MU1.
[0039] As shown in the figure, Figure 3 , Figure 6 and Figure 9As shown, the key circuit includes a first key K1, a second key K2, a third key K3, a fourth key K4, a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4. The first end of the first resistor R1 is connected to the P0.13 terminal of the control chip MU1, the second end of the first resistor R1 is connected to the first end of the first key K1, the first end of the second resistor R2 is connected to the P0.14 terminal of the control chip MU1, the second end of the second resistor R2 is connected to the first end of the second key K2, the first end of the third resistor R3 is connected to the P0.15 terminal of the control chip MU1, the second end of the third resistor R3 is connected to the first end of the third key K3, the first end of the fourth resistor R4 is connected to the P0.16 terminal of the control chip MU1, the second end of the fourth resistor R4 is connected to the first end of the fourth key K4, and the second end of the first key K1 is respectively connected to the second end of the second key K2, the second end of the third key K3, and the second end of the fourth key K4 and then grounded.
[0040] The working principle of this utility model is as follows:
[0041] like Figures 1-9 As shown, the utility model accurately controls the rotation of the servo motor through the control circuit, thereby driving the disc and indicator label on the dial assembly to rotate according to a preset angle, thereby realizing the precise positioning of the indication function. At the same time, the voltage stabilizing circuit and the voltage step-down circuit work together to ensure that the control circuit and the servo motor obtain a stable and appropriate voltage supply, thereby ensuring the stable operation of the entire system. The dial assembly is composed of a dial 5, scale lines 4, a guide rail 3, a disc 2 and an indicator label 1. When the servo motor receives a driving signal from the control circuit, its output shaft is connected to the center of the disc 2 through the rotating shaft 9, driving the disc 2 and the indicator label 1 to rotate on the guide rail 3. As the disc 2 rotates, the indicator label 1 points to different scale lines 4, thereby realizing the indication function of a specific parameter. Since the servo motor has the characteristics of high precision and high stability, it can ensure that the indicated position of the indicator label 1 is accurate.
[0042] The control circuit consists of the control chip MU1, a motor drive circuit, a keypad circuit, and a screen display circuit. The control chip MU1 receives command signals from the keypad circuit and parses and processes them according to its built-in program logic. Subsequently, the control chip MU1 sends control signals to the servo motor via the motor drive circuit, driving the servo motor to rotate according to the preset pattern. Simultaneously, the control chip MU1 communicates with the screen display circuit, displaying the current operating status and setting parameters for easy user observation and adjustment.
[0043] The voltage stabilizing circuit is mainly composed of a fuse F1, resistors, capacitors, inductors and a voltage stabilizing chip U1, etc. When the power is connected, first, the fuse F1 is used for short circuit protection to prevent the subsequent circuit from being damaged by excessive current. Then, the input voltage is preliminarily divided by the slide rheostat MOV1 and the thirteenth resistor R13, and is sent to the voltage stabilizing chip U1 for precise voltage stabilizing treatment. The voltage stabilizing chip U1 uses the internal feedback mechanism to automatically adjust the internal circuit according to the difference between the output voltage and the reference voltage, so as to ensure that the output voltage is stabilized at the preset value. Finally, the filter capacitors (such as the fifth capacitor C5 and the sixteenth capacitor C16, etc.) are used to filter out high-frequency noise, and the stable DC voltage is output for the subsequent circuit.
[0044] The voltage reducing circuit is composed of a voltage reducing chip U3 and its peripheral elements, which is responsible for further reducing the higher voltage output by the voltage stabilizing circuit to the lower voltage required by the control circuit and the servo motor. The VIN end of the voltage reducing chip U3 receives the output voltage from the voltage stabilizing circuit and performs voltage reduction processing through the internal circuit. At the same time, the ripple generated in the voltage reduction process is filtered out by the filter capacitors such as the nineteenth capacitor C19 and the forty-sixth capacitor C46, so as to ensure the smooth and stable output voltage. Finally, the VOUT end of the voltage reducing chip U2 outputs a stable 3.3V voltage, which is used for the control circuit and the servo motor.
[0045] The motor driving circuit uses a driving chip U5 as the core element, controls the MOTOR_EN (enable end) and MOTOR_CS (control end) of the driving chip through the P0.23 end and the P0.24 port of the control chip MU1, respectively, to realize the start-stop and speed regulation of the servo motor. In addition, the driving chip U5 is also connected to the fifth light emitting diode LED5 through the LED_OUT end as a status indicator lamp, which is used to indicate the current working state of the servo motor.
[0046] The above only describes the preferred embodiments of the present application, and is not used to limit the protection scope of the present application.
Claims
1. A 360° RSSI test fixture, comprising: The application relates to a clock, which comprises a dial assembly, a shell assembly, a servo motor, a control circuit, a voltage stabilizing circuit and a voltage reducing circuit.
2. The 360° RSSI test fixture of claim 1, wherein, The shell assembly comprises a shell and a base.
3. The 360° RSSI test fixture of claim 2, wherein, The dial assembly comprises a dial, a scale line, a guide rail, a disc and an indicating label.
4. The 360° RSSI test fixture of claim 3, wherein, The servo motor is arranged in the shell and mounted on the base.
5. The 360° RSSI test fixture of claim 4, wherein, The voltage stabilizing circuit comprises a fuse, a thirteenth resistor, a sliding rheostat, a first capacitor, a twenty-fourth resistor, a twenty-ninth resistor, a second inductor, a voltage stabilizing chip, a first inductor, a fifty-second capacitor, a fifty-third capacitor, a fifth capacitor, a sixteenth capacitor, an eighteenth capacitor and a third diode.
6. The 360° RSSI test fixture of claim 5, wherein, The voltage reduction circuit includes a voltage reduction chip, a forty-sixth capacitor, a nineteenth capacitor, a twenty-seventh capacitor, a forty-fifth capacitor, a 3.3V power output end, the VIN end of the voltage reduction chip is connected with the CE end of the voltage reduction chip, the first end of the nineteenth capacitor, the first end of the forty-sixth capacitor and the negative electrode of the second diode respectively, the second end of the forty-sixth capacitor is connected with the second end of the nineteenth capacitor and the VSS end of the voltage reduction chip and then grounded, the VOUT end of the voltage reduction chip is connected with the first end of the twenty-seventh capacitor, the first end of the forty-fifth capacitor and the 3.3V power output end respectively, and the second end of the twenty-seventh capacitor and the second end of the forty-fifth capacitor are grounded.
7. The 360° RSSI test fixture of claim 6, wherein, The control circuit includes a control chip, a motor driving circuit, a key circuit and a screen display circuit, the power input end V of the control chip is connected with the 3.3V power output end, the signal output end of the key circuit is connected with the input end of the control chip, the output end of the control chip is connected with the input end of the screen display circuit, the control chip is connected with the motor driving circuit in communication, and the motor driving circuit is connected with the servo motor.
8. The 360° RSSI test fixture of claim 7, wherein, The motor driving circuit includes a driving chip, a thirty-first resistor and a fifth light emitting diode, the MOTOR_CS end of the driving chip is connected with the P0.24 end of the control chip, the MOTOR_EN end of the driving chip is connected with the P0.23 end of the control chip, and the LED_OUT end of the driving chip is connected with the thirty-first resistor and the fifth light emitting diode in series and then grounded.
9. The 360° RSSI test fixture of claim 8, wherein, The screen display circuit includes a screen display interface, the SCL end of the screen display interface is connected with the P0.11 end of the control chip, and the SDA end of the screen display interface is connected with the P0.12 end of the control chip.
10. The 360° RSSI test fixture of claim 9, wherein, The key circuit includes a first key, a second key, a third key, a fourth key, a first resistor, a second resistor, a third resistor and a fourth resistor, the first end of the first resistor is connected with the P0.13 end of the control chip, the second end of the first resistor is connected with the first end of the first key, the first end of the second resistor is connected with the P0.14 end of the control chip, the second end of the second resistor is connected with the first end of the second key, the first end of the third resistor is connected with the P0.15 end of the control chip, the second end of the third resistor is connected with the first end of the third key, the first end of the fourth resistor is connected with the P0.16 end of the control chip, the second end of the fourth resistor is connected with the first end of the fourth key, and the second end of the first key is connected with the second end of the second key, the second end of the third key and the second end of the fourth key and then grounded.