Magnetic induction intensity measuring circuit

Abstract

The utility model discloses a magnetic induction intensity measuring circuit, comprising a magnetic field measuring circuit used for detecting and outputting a set magnetic induction intensity signal and an internal temperature signal; the analog-to-digital conversion circuit is used for converting the received magnetic induction intensity signal and the temperature signal into digital signals and outputting the digital signals; the control circuit is used for receiving the converted magnetic induction intensity signal and temperature signal and outputting a corresponding control signal; the temperature management circuit is used for realizing the driving control of the Peltier element according to the control signal output by the control circuit so as to realize the temperature control of the magnetic sensor; and the power conversion circuit is used for providing working voltage. In the process of building the magnetic induction intensity measuring circuit, the working temperature management of the Hall magnetic sensor is further realized through the driving control of the Peltier element, so that the Hall magnetic sensor works in the optimal temperature state as much as possible, and the measuring precision is improved.

Description

Technical Field

[0001] This utility model relates to the field of magnetic field measurement technology, specifically to a magnetic induction intensity measurement circuit. Background Technology

[0002] A Hall sensor is a sensor that utilizes the Hall effect to measure magnetic fields by converting magnetic field signals into corresponding electrical signals. Therefore, it is widely used in industrial control systems, automobiles, and intelligent instruments.

[0003] Hall effect sensors use semiconductor devices, whose mobility and impurity concentration change with ambient temperature. This alters the sensitivity of the Hall device, significantly affecting its linearity and limiting its application in high-precision measurement scenarios. Test results show that the sensitivity of the Hall device changes non-linearly with temperature, making it difficult for traditional temperature drift compensation circuits to meet high-precision measurement requirements.

[0004] Therefore, in the process of building the magnetic induction intensity measurement circuit, it is also necessary to further realize the operating temperature management of the magnetic induction sensor to make it work at the optimal temperature as much as possible, thereby improving the measurement accuracy of magnetic induction intensity and providing strong support for the expansion of applications in high-precision measurement scenarios, such as the magnetic field measurement of transcranial magnetic stimulation (TMS) therapy devices. Utility Model Content

[0005] Purpose of the invention: To address the above-mentioned shortcomings, this utility model provides a magnetic induction intensity measurement circuit, which further manages the operating temperature of the magnetic induction sensor by driving a Peltier element, so that it can operate at the optimal temperature as much as possible, thereby improving the measurement accuracy of magnetic induction intensity.

[0006] Technical solution: To achieve the above objectives, this utility model provides a magnetic induction intensity measuring circuit, comprising:

[0007] The magnetic field measurement circuit includes a magnetic induction sensor for detecting and outputting a set magnetic induction intensity signal and an internal temperature signal.

[0008] The analog-to-digital conversion circuit includes an analog-to-digital converter, which receives the magnetic induction intensity signal and temperature signal output by the magnetic induction sensor and converts them into corresponding digital signals for output;

[0009] The control circuit, including a microprocessor, is used to receive the converted magnetic induction intensity signal and temperature signal, and output corresponding control signals to the magnetic field measurement circuit, the analog-to-digital conversion circuit and the temperature management circuit.

[0010] A temperature management circuit includes a Peltier element and a Peltier driving circuit, wherein the Peltier element is attached to a magnetic induction sensor, and the Peltier driving circuit is used to drive the Peltier element according to the Peltier control signal output by the microprocessor, thereby realizing the operating temperature control of the magnetic induction sensor.

[0011] A power conversion circuit is used to provide the operating voltage.

[0012] Furthermore, it also includes a serial communication circuit, which includes an external communication interface and a protocol conversion circuit. The microprocessor connects to the external communication interface via the protocol conversion circuit to achieve data transmission.

[0013] Specifically, the power conversion circuit includes a linear regulator circuit and an LED indicator circuit, wherein the linear regulator circuit is used to convert the externally input +5V voltage into a stable +3.3V voltage output, and the LED indicator circuit is used to display the operating status of the +3.3V voltage.

[0014] Specifically, the magnetic induction sensor has three orthogonally distributed Hall sensors built in, which can simultaneously measure the magnetic induction intensity signals in three orthogonal directions.

[0015] Furthermore, the magnetic field measurement circuit also includes a DIP switch. The configuration pin of the magnetic induction sensor is connected to a high level through the DIP switch, thereby controlling the level of the configuration pin by switching the DIP switch on and off, thereby controlling the measurement range and measurement direction of the magnetic induction sensor.

[0016] Furthermore, the magnetic field measurement circuit also includes a low-power control circuit for controlling the low-power mode of the magnetic induction sensor based on the low-power control signal output by the microprocessor.

[0017] Specifically, the low-power control circuit includes a transistor Q2 and a field-effect transistor Q1. The low-power output pin of the microprocessor is connected to the base of transistor Q2 through resistor R39. The base of transistor Q2 is grounded through resistor R41. The collector of transistor Q2 is connected to +5V through resistor R40, and its emitter is grounded. The source of field-effect transistor Q1 is connected to +5V, its gate is connected to the collector of transistor Q2 through resistor R42, and its drain is connected to the low-power input pin of the magnetic induction sensor. Thus, the on / off state of transistor Q2 controls the on / off state of field-effect transistor Q1, thereby achieving level control of the input pin. By setting the control signal output by the pin (such as high / low level switching) through the microprocessor, the magnetic induction sensor is triggered to enter a low-power mode (non-measurement period), reducing the overall system power consumption and waking up the sensor only during the measurement cycle.

[0018] Specifically, the Peltier drive circuit includes a Peltier socket and a Peltier drive chip. The Peltier drive chip is used to output a corresponding Peltier drive signal to the Peltier socket according to the Peltier control signal output by the microprocessor. The Peltier socket is used to connect the Peltier element and output a corresponding Peltier drive signal to the Peltier element, thereby switching the cooling / heating mode.

[0019] Furthermore, the temperature management circuit also includes a cooling fan and a cooling fan control circuit, wherein the cooling fan is positioned toward the Peltier element, and the cooling fan control circuit is used to drive the cooling fan according to the fan control signal output by the microprocessor, thereby realizing the heat dissipation control of the Peltier element.

[0020] Specifically, the cooling fan control circuit includes a fan socket for connecting a cooling fan and for driving and controlling the cooling fan based on the PWM signal output by the microprocessor.

[0021] Beneficial effects: In the process of building the magnetic induction intensity measurement circuit, this utility model uses a microprocessor to determine the threshold of the working temperature of the magnetic induction sensor, and outputs a corresponding control signal to drive the Peltier element to perform heating or cooling, thereby completing the working temperature compensation of the magnetic induction sensor and making it work at the optimal temperature as much as possible, which effectively improves the measurement accuracy of magnetic induction intensity. Attached Figure Description

[0022] Figure 1 This is a block diagram of the overall circuit structure of an embodiment of the present utility model;

[0023] Figure 2 This is a circuit diagram of the power conversion circuit in an embodiment of the present invention;

[0024] Figure 3 This is a circuit diagram of the MV2 magnetic sensor measurement circuit in an embodiment of this utility model;

[0025] Figure 4 This is a circuit diagram of the analog-to-digital conversion circuit in an embodiment of this utility model;

[0026] Figure 5 This is a circuit diagram of the microprocessor control circuit in an embodiment of the present invention;

[0027] Figure 6 This is a circuit diagram of the Peltier thermal management circuit in an embodiment of this utility model;

[0028] Figure 7 This is a circuit diagram of the USB-to-serial communication circuit in an embodiment of this utility model;

[0029] Figure 8This is a schematic diagram of the Peltier element and cooling fan in the embodiments of this utility model;

[0030] The diagram includes: 1. Circuit board, 2. Peltier component, 3. Cooling fan. Detailed Implementation

[0031] To make the objectives, features, and advantages of this utility model more apparent and understandable, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0032] Reference Figure 1 The magnetic induction intensity measurement circuit provided by this utility model includes a power conversion circuit, an MV2 magnetic sensor measurement circuit (i.e., a magnetic field measurement circuit), an analog-to-digital conversion circuit, a microprocessor control circuit, a Peltier thermal management circuit (i.e., a temperature management circuit), and a USB to serial communication circuit (i.e., a serial communication circuit).

[0033] Specifically, the power conversion circuit includes a linear regulator circuit to convert the externally input +5V voltage into a stable +3.3V output voltage, thereby powering other circuits. Furthermore, the power conversion circuit also includes an LED indicator circuit, which, by establishing a "power supply-resistor-LED-ground" loop, provides visual feedback on whether the +3.3V power supply is working properly, facilitating debugging and troubleshooting.

[0034] For example, refer to Figure 2The linear regulator circuit includes a low-dropout linear regulator U6 (model SP6205EM5-L-3-3 / TR) and a DC power socket DC1 (model DC-005-A200). The linear regulator U6 is used to regulate the externally input +5V voltage to a +3.3V output voltage, thereby providing a stable low-voltage power supply for the system. The DC power socket DC1 is used to connect an external +5V DC power supply (such as an adapter). Pin 1 is connected to the positive input of the power supply, and pins 2 and 3 are grounded. Pin 1 is also connected to pin 1 of a rocker switch SW2 (model SS-12D10L5). Pin 2 of the rocker switch SW2 is grounded through a filter capacitor C69, thereby filtering out high-frequency noise from the +5V power supply and improving stability. Pin 3 of the rocker switch SW2 is open, and the rocker switch SW2 controls the power supply. When the switch is toggled to pin 3, the circuit is de-energized; when the switch is toggled to pin 2, the circuit is closed and connected to the +5V voltage. Pin 1 of the linear regulator U6 is the voltage input pin (IN), connected to +5V via pin 2 of the rocker switch SW2. Pin 2 is also the ground pin (GND), providing a circuit reference ground. Pin 3 is the enable pin (EN), the chip operates when high and shuts off when low (in this embodiment, it is directly connected to +5V and is always enabled by default). Pin 4 is the bypass / adjustment pin (BYP / ADJ), connected to ground via an external capacitor C71 for further filtering and improving the purity of the output voltage. Pin 5 is the regulated output pin (OUT), used to output a +3.3V voltage signal (+3V3) to power subsequent circuits. It also filters again via ground through capacitor C70, removing residual noise after regulation and ensuring a stable +3.3V voltage with low ripple. Additionally, the LED indicator circuit includes an LED (LTST-C190YKT) for visually indicating whether the +3.3V power supply is normal. The +3V3 voltage signal is connected to the LED via a current-limiting resistor R37 to limit the LED's operating current and prevent overcurrent damage. The other end of the LED is grounded, forming a current loop.

[0035] Specifically, the MV2 magnetic sensor measurement circuit mainly includes an MV2 digital triaxial Hall magnetic sensor U3, which incorporates three orthogonally distributed Hall sensors to simultaneously measure the three components of the magnetic field (Bx, By, Bz) and output an internal temperature signal. Furthermore, the MV2 magnetic sensor measurement circuit also includes a DIP switch SW1, which allows for flexible setting of the measurement range and direction of the magnetic sensor U3. In addition, the MV2 magnetic sensor measurement circuit includes a low-power control circuit for controlling the magnetic sensor U3 in a low-power mode based on the low-power control signal output by the microprocessor U1.

[0036] For example, refer to Figure 3Pin 8 of the magnetic sensor U3 is the detection voltage pin VDD, used to connect to a +3.3V voltage signal (+3V3) to ensure that the sensor element can accurately sense the magnetic field signal. It is grounded through auxiliary filter capacitors C47 and C48 to further stabilize the voltage, suppress ripple, and ensure stable sensor operation. Pin 14 is the communication voltage pin VCC, used to connect to a +5V voltage to ensure sufficient driving capability for the communication signal. It is also grounded through filter capacitors C45 and C46 to filter out high-frequency noise from the +5V power supply, making the power supply cleaner. Pin 7 is the reference voltage positive pin REFX1, which is designed to be floating in this embodiment. Pin 9 is the digital and analog signal function pin DA, which, when shorted, connects to a +5V voltage to select the analog signal output format. Pin 13 is the ground pin GND, used for grounding. Pins 11 and 12... The auxiliary function pins INV and EMR are active high, and grounding is disabled in this embodiment. Pin 10 is the low-power input pin LP, which is enabled by a high level of +5V. In this embodiment, the high and low levels are output through pin 29 LP1 of the microprocessor U1 to the low-power control circuit composed of transistor Q2 and field-effect transistor Q1 for control. Pins 1 and 2 are configuration pins RA0 and RA1, used to set the magnetic field measurement range. Pins 3 and 4 are configuration pins MA0 and MA1, used to set the magnetic field measurement axis (i.e., measurement direction). Pins 16, 15, and 5 are magnetic field output pins, used to output the magnetic field components in the X, Y, and Z axes, respectively, i.e., analog signals X, Y, and Z. Pin 6 is the temperature output pin, used to output the internal operating temperature of the magnetic sensor U3, i.e., the analog signal TEMP.

[0037] Furthermore, pins 1 and 2 of the magnetic sensor U3 are configuration pins for the measurement range. By setting different level states (0 or 1) on these two pins, different magnetic field measurement ranges can be selected.

[0038] When RA1=0 and RA0=0, the magnetic field measurement range of sensor U3 is ±100 mT;

[0039] When RA1=0 and RA0=1, the magnetic field measurement range of sensor U3 is ±300 mT;

[0040] When RA1=1 and RA0=0, the magnetic field measurement range of sensor U3 is ±1 T;

[0041] When RA1=1 and RA0=1, the magnetic field measurement range of sensor U3 is ±3 T.

[0042] Meanwhile, pins 3 and 4 of the magnetic sensor U3 are configuration pins for the magnetic field measurement axis. By setting different level states (0 or 1) on these two pins, different magnetic field measurement axes can be selected.

[0043] When MA1=0 and MA0=0, sensor U3 is set to 3 axes (three-axis mode), cyclically scanning the X, Y, and Z axes and amplifying the signal;

[0044] When MA1=0 and MA0=1, sensor U3 is set to X axes (X-axis mode), stops scanning, and only amplifies the X-axis Hall element signal;

[0045] When MA1=1 and MA0=0, sensor U3 is set to Y axes (Y-axis mode), stops scanning, and only amplifies the Y-axis Hall element signal;

[0046] When MA1=1 and MA0=1, sensor U3 is set to Z axes (Z-axis mode), stops scanning, and only amplifies the Z-axis Hall element signal.

[0047] Continue to refer to Figure 3 Pins 1, 2, 3, and 4 are connected to DIP switch SW1. DIP switch SW1 controls the on / off state of these pins, thereby controlling the testing function of magnetic sensor U3. Specifically, DIP switch SW1 (model DSHP04TS-S) is used to control the pin levels of magnetic sensor U3. Pins 1-4 of DIP switch SW1 are connected to +5V, and pins 5-8 are connected to pins 1 (RA0), 2 (RA1), 3 (MA0), and 4 (MA1) of magnetic sensor U3, respectively. By toggling DIP switch SW1, the voltage levels of these pins can be changed. By toggling DIP switch SW1, users can easily change the voltage level combination of pins RA0 and RA1, thus flexibly selecting the appropriate magnetic field measurement range according to the needs of the actual application scenario. Simultaneously, users can also easily change the voltage level combination of pins MA0 and MA1 to quickly switch between single-axis and tri-axis modes, verifying the influence of magnetic fields in different directions on the system.

[0048] Furthermore, continue to refer to Figure 3The low-power control circuit includes a transistor Q2 of model S9013 and a field-effect transistor Q1 of model AO3401A. The high-level signal output from pin 29 LP1 of microprocessor U1 is input through resistor R39. Resistors R39 and R41 form a voltage divider circuit, so that the base of transistor Q2 receives a suitable voltage to meet the conduction condition. After transistor Q2 conducts, the collector of transistor Q2 is connected to a +5V voltage, which controls the field-effect transistor Q1 to conduct. The +5V voltage is transmitted to the LP terminal through the field-effect transistor Q1, and LP becomes high level (+5V), which is connected to pin 10 of magnetic sensor U3, triggering magnetic sensor U3 to enter the low-power working mode. Preferably, the +5V voltage is grounded through capacitor C72, which serves as a power supply filter, filtering out high-frequency noise on the +5V power line, ensuring voltage stability, and preventing voltage fluctuations from causing the field-effect transistor Q1 to be mistakenly turned on or off. The collector of transistor Q2 is connected to the +5V voltage through resistor R40, providing a pull-up path for the gate of field-effect transistor Q1. When transistor Q2 is off, resistors R40 and R42 pull up the gate of field-effect transistor Q1 to +5V, ensuring that field-effect transistor Q1 is reliably turned off and preventing the magnetic sensor U3 from mistakenly entering the low-power mode.

[0049] Specifically, the analog-to-digital conversion circuit mainly includes an analog-to-digital converter U2, which receives the magnetic induction intensity component signal and temperature signal output by the magnetic sensor U3, and converts them into high-precision digital quantities for transmission to the microprocessor U1. Furthermore, the microprocessor U1 is connected to the analog-to-digital converter U2 via an SPI interface, thereby acquiring the converted magnetic induction intensity component signal and temperature signal. In addition, the microprocessor U1 also outputs corresponding control signals to the analog-to-digital converter U2, thereby enabling the start-up and reset of the analog-to-digital converter U2.

[0050] For example, refer to Figure 4The analog-to-digital converter (ADC) circuit mainly includes an ADS124S08IPBSR ADC U2. Pins 15 and 16 of ADC U2 are the digital power supply pins IOVDD and DVDD, connected to a +3.3V power supply signal (+3V3). High-frequency noise is filtered out by decoupling capacitor C54 to ensure stable power supply and normal operation of the internal circuitry. Pin 26 is the analog power supply pin AVDD, connected to a +5V power supply. Power ripple is filtered out by capacitor C52 to supply analog power. The circuit provides a clean power supply; pins 14, 27, and 28 are ground pins (DGND, AVSS, AVSS-SW), all grounded; pins 9, 10, 11, 12, and 13 are SPI communication pins (CS#, DIN, SCLK, DOUT, DRDY#), connected to pins 18, 17, 15, 16, and 14 of the microprocessor U1 via resistors R21-R25 respectively. Resistors R21-R25 serve as current limiters and impedance matching to ensure SPI communication. The stability of the signal is ensured by the following pins: Pins 23 and 24 are the reference voltage output pins REFOUT and REFCOM, respectively. Pin 24 is grounded, and pin 23 is used to provide a stable reference voltage REFOUT (grounded through filter capacitor C53). These pins form input differential pairs with the analog output signals X, Y, and Z of the magnetic sensor U3 to measure the magnitude of the input analog signal. Pins 2, 3, 4, 5, 6, and 7 are analog input pins. Analog-to-digital conversion is performed by constructing differential pairs. Specifically, the reference voltage REFOUT connected to pin 2 and the analog output signal X connected to pin 3 form a differential pair; the reference voltage REFOUT connected to pin 4 and the analog output signal Z connected to pin 5 form a differential pair; and the reference voltage REFOUT connected to pin 6 and the analog output signal Y connected to pin 7 form a differential pair. Pin 20 is also an analog input pin, used to connect to the analog output signal TEMP of the magnetic sensor U3 to complete the analog-to-digital conversion of the temperature signal. Pin 17 is the external clock input pin CLK, which is grounded. In addition, it also includes the control pins of the analog-to-digital converter U2: pin 8 is the start-up pin START, which is triggered by a high-level output from pin 19 of the microprocessor U1, thereby controlling the start-up operation of the analog-to-digital converter U2; pin 18 is the reset pin RESET#, which is connected to the reset signal RESET output from pin 13 of the microprocessor U1 through the voltage divider resistor R20, thereby controlling the reset operation of the analog-to-digital converter U2.

[0051] Specifically, the microprocessor control circuit mainly includes a microprocessor U1. On one hand, it coordinates and controls the entire measurement circuit, including controlling the startup and reset of the analog-to-digital converter U2, and controlling the low-power mode of the magnetic sensor U3. On the other hand, it acquires the magnetic induction intensity component signal and temperature signal output by the analog-to-digital converter U2 through the SPI communication interface, and after calculation and logical judgment (i.e., threshold judgment), outputs the corresponding Peltier control signal to the Peltier thermal management circuit, thereby controlling the temperature rise or fall of the Peltier load, thus realizing the operating temperature control of the magnetic sensor U3. Furthermore, the microprocessor U1 can also drive the cooling fan 3 to remove the cold or heat transferred by the Peltier element 2, ensuring that the Peltier element 2 operates at a relatively stable temperature. In addition, the microprocessor U1 has a built-in 64KB Flash memory and 20KB SRAM. The Flash memory is used to store program code and some data that needs to be stored for a long time, while the SRAM is used for temporary data storage during program execution.

[0052] For example, refer to Figure 5The microprocessor control circuit includes a microprocessor U1 of model STM32F103C8T6. Pins 1, 24, 36, and 48 of the microprocessor U1 are digital power input pins (VDD), connected to a +3.3V power signal (+3V3) to power the internal digital circuitry. Parallel capacitors C60-C64 form a decoupling network to filter high-frequency noise and ripple on the power lines, ensuring stable operation of the digital circuitry. Pin 9 is the analog power input pin (VDDA), connected to a +3.3V power signal (+3V3) to power the internal analog circuitry. Parallel capacitors C65 and C66 filter the analog signal to ensure the accuracy of analog signal processing and prevent digital power noise from interfering with the analog section. Pins 23, 35, and 47 are digital ground pins. Pins VSS and VSSA are analog ground pins. All ground pins are directly connected to system ground (GND) to form a unified ground reference, providing a zero-potential reference point for the entire chip and ensuring effective power supply voltage application and signal level stability. Pins 5 and 6 are clock-related pins. Pin 5 is the external high-speed clock (HSE) input OSC_IN signal, and pin 6 is the external high-speed clock (HSE) output OSC_OUT signal. An 8MHz crystal oscillator X1 is connected between the two pins and grounded through capacitors C58 and C59 respectively. The crystal oscillator X1, along with capacitors C58 and C59, forms an oscillation circuit to provide an 8MHz reference clock for the chip. Pin 7 is the reset control pin NRST. A low level triggers chip reset and is pulled up to +3 through resistor R32.A 3V power supply signal +3V3, along with a series capacitor C57 grounded, forms an RC reset circuit. Upon power-up, capacitor C57 charges, initially keeping the NRST pin low (triggering a reset). Once the capacitor is fully charged, NRST is pulled high, the chip exits the reset state and begins operation. Alternatively, a manual reset can be achieved by shorting NRST with jumper cap T1 (model TS-1101-CW). Pin 13 is the reset output pin (RESET), connected to pin 18 of analog-to-digital converter U2 via voltage divider resistor R20, controlling the reset operation of analog-to-digital converter U2. It is active low. Pins 14, 15, 16, and 1... Pins 7 and 18 are SPI communication pins DRDY, SCLK, MISO, MOSI, and CS, respectively, connected to pins 13, 11, 12, 10, and 9 of the analog-to-digital converter U2 to achieve high-speed synchronous serial data transmission, thereby sending configuration commands or reading data. Pin 19 is the start output pin START, connected to pin 8 of the analog-to-digital converter U2, used to control the start of the analog-to-digital converter U2, active high. Pins 20 and 44 are the start configuration pins BOOT0 and BOOT1, respectively. Pin 44 is pulled down to ground through resistor R34 (BOOT0=0), defaulting to "boot from internal Flash" (normal operating mode), in which case the chip executes the user program burned into the internal Flash. Pin 20 is pulled down to ground through resistor R33, defaulting to "boot from internal Flash" in conjunction with BOOT0=0. "Startup" Furthermore, pin 44 is also connected to a jumper cap T2 (model TS-1101-CW), pulled up to +3.3V power signal +3V3. Shorting jumper cap T2 allows manual startup from system memory for firmware upgrades. Pins 21 and 22 are serial communication pins, connected to pins 7 and 6 of the USB-to-serial chip U5, used for serial communication between microprocessor U1 and USB-to-serial chip U5. Pin 25 is the sleep control pin NSLEEP, connected to pin 7 of Peltier driver chip U4, active low, controlling Peltier driver chip U4 to enter sleep mode, reducing power consumption. Pins 26 and 27 are control output pins IN1 and IN2, connected to pins 5 and 6 of Peltier driver chip U4. The Peltier driver chip U4 is used to control its output state, thereby controlling the operating mode (cooling / heating) of the Peltier element 2. Pin 28 is the fan control pin FPWM, connected to pin 3 of the fan socket CN2 via voltage divider resistor R31, thus controlling the fan speed to achieve heat absorption and air dissipation, ensuring stable operation of the Peltier. Pin 29 is the low-power output pin LP1, which triggers the magnetic sensor U3 to operate in low-power mode via a high level. Pins 37 and 34 are the debug interface pins SWCLK and SWDIO, respectively, led out through pin header P1 and connected to the SWCLK and SWDIO signals of an external debugger for program download (burning to internal Flash) and online debugging (single-step execution, breakpoints, viewing registers, etc.).

[0053] Specifically, the Peltier thermal management circuit includes a Peltier element 2 and a Peltier driving circuit. The Peltier element 2 is attached to the magnetic sensor U3. The Peltier driving circuit controls the drive of the Peltier element 2 according to the Peltier control signal output by the microprocessor U1, thereby compensating for the operating temperature required by the magnetic sensor U3. Further, the Peltier thermal management circuit also includes a cooling fan 3 and a cooling fan control circuit. The cooling fan 3 is positioned towards the Peltier element 2. The cooling fan control circuit controls the drive of the cooling fan 3 according to the fan control signal output by the microprocessor U1, thereby controlling the heat dissipation of the Peltier element 2.

[0054] For example, refer to Figure 6 , Figure 8 The Peltier drive circuit includes a Peltier socket CN1 (model ZX-XH2.54-2PZZ) and a Peltier drive chip U4 (model DRV8212PDSGR). The Peltier socket CN1 is soldered to the circuit board 1 on the back of the magnetic sensor U3 to install and fix the Peltier element 2, so that the magnetic sensor U3 is attached to the Peltier element 2 on the back through the thin circuit board 1. The Peltier drive chip U4 is a dual-channel H-bridge motor / actuator drive chip, used to drive the Peltier element 2 to transfer heat in the forward / reverse direction, thereby realizing the switching between cooling and heating. The cooling fan control circuit includes a fan socket CN2 (model ZX-XH2.54-3PZZ), which is fixed to the periphery of the Peltier element 2 by bolt assembly to install and fix the cooling fan 3. The microprocessor U1 outputs a PWM pulse signal to drive the cooling fan 3 to draw away the cold or hot air near the circuit, ensuring that the Peltier element 2 operates at a relatively stable temperature.

[0055] More specifically, the Peltier socket CN1 has a 2-pin interface for connecting the Peltier element 2 (model ATE1-49-2AS) to transmit OUT1 and OUT2 drive signals. Pins 1 and 8 of the Peltier driver chip U4 are the analog and digital power supply pins VM and VCC, respectively. Pin 1 is connected to +5V and uses decoupling capacitor C56 to filter high-frequency noise, ensuring a stable drive voltage for the Peltier element 2. Pin 8 is connected to +3V3 to power the chip's logic control and is grounded through decoupling capacitor C55 for decoupling and filtering, ensuring accurate chip control logic. Pin 4 is the ground pin GND. Pins 2 and 3 are the output pins O. UT1 and OUT2 are connected to pins 1 and 2 of the Peltier socket CN1, respectively. By changing the output level / current direction, the heat transfer direction of the Peltier element 2 is controlled, thereby switching between cooling and heating modes. Pins 5 and 6 are logic input pins IN2 and IN1, connected to pins 27 and 26 of the microprocessor U1. The high and low level combinations (IN1=1 / IN2=0 for cooling, IN1=0 / IN2=1 for heating) control the OUT1 and OUT2 signals output by the Peltier driver chip U4. Pin 7 is the sleep control pin NSLEEP, connected to pin 25 of the microprocessor U1. It sleeps at a low level and works at a high level. Pin 9 is an exposed pad with a floating design. Preferably, pin 3 of the Peltier driver chip U4 outputs the OUT2 signal through a filter and current-limiting circuit composed of inductor L1 and resistor R30. This stabilizes the output circuit and protects the Peltier element 2 and the Peltier driver chip U4. Inductor L1 smooths the current, reducing the impact of sudden current changes, while resistor R30 can be used for current detection, helping to monitor the current flowing through the Peltier element 2. Furthermore, the fan socket CN2 has a 3-inch interface for connecting the cooling fan 3. Pin 1 is connected to the +5V power supply, pin 2 is grounded, and pin 3 is connected to pin 28 of the microprocessor U1 through a current-limiting voltage divider resistor R31. The PWM signal output by the microprocessor U1 controls the fan speed to achieve heat dissipation / cooling, ensuring the normal operation of the Peltier.

[0056] Specifically, the USB-to-serial communication circuit is used to convert data between the USB Type-C interface and the serial port (UART), thereby enabling external communication, program downloading, etc. It mainly includes a USB interface circuit and a USB bus conversion circuit. The USB interface circuit is mainly used to provide a USB interface that enables program downloading, device debugging, and data pass-through, while the USB bus conversion circuit is used to convert between the USB protocol and the serial port (UART) protocol.

[0057] For example, according to Figure 7The USB interface circuit mainly includes a USB connector USB1, model Type-C 16PIN 2MD (073), which enables communication with the USB physical interface of an external computer. Pins 2 and 11 of USB1 are the bus power pins VBUS, connected to +5V in this embodiment; pins 1 and 12 are the ground pins GND, used for grounding and providing a level reference for the USB interface; pins 3 and 9 are spare channel pins, not used in this embodiment; pins 4 and 10 are the configuration channel pins CC1 and CC2, pulled down to ground through resistors R35 and R36 respectively, adapting to USB 2.0 slave mode; pins 13 and 14 are the shell ground pins SHELL. In this example, the pins are left floating. Pins 6, 7, 8, and 5 are communication pins DP1, DN1, DP2, and DN2, respectively. Their connection to the USB-to-serial chip U5 follows the USB differential signal transmission specification: DP1 and DN1 are a pair of USB differential signals (DP is differential positive, DN is differential negative), connected to UD+ (pin 1) and UD- (pin 2) of the USB-to-serial chip U5, respectively, serving as the main channel for USB data interaction. DP2 and DN2 are another pair of spare differential signals, which can be connected in parallel with the main signal pair DP1 and DN1 in the circuit via a 0Ω resistor (or directly shorted). Furthermore, pins 4 and 10 of USB1 are further shorted to the data differential pins 6 and 8, which helps improve the stability and reliability of data transmission.

[0058] Furthermore, the USB bus adapter circuit mainly includes a USB-to-serial chip U5, model CH340N. Pin 1 of the USB-to-serial chip U5 is the USB data positive terminal UD+, connected to the DP1 / DP2 pins of USB connector USB1 (a differential pair after shorting); pin 2 is the USB data negative terminal UD-, connected to the DN1 / DN2 pins of USB connector USB2 (a differential pair after shorting); pin 3 is the ground pin GND, used for grounding and providing a reference ground for the chip; pin 4 is the request transmit pin RT. S# is left unconnected in this embodiment; pin 5 is the power input pin VCC, connected to the +3.3V power signal +3V3, providing power to the chip's internal logic circuits and working modules, and grounded through capacitor C68 to decouple and filter high-frequency noise on the power line; pin 6 is the serial data transmitter TXD, connected to pin 22 of microprocessor U1; pin 7 is the serial data receiver RXD, connected to pin 21 of microprocessor U1; pin 8 is the internal power-related pin, connected to the +3.3V power signal +3V3, and grounded through decoupling and filtering via capacitor C67.

[0059] Combining the above circuit, this utility model realizes the process of magnetic induction intensity measurement and temperature compensation control based on a magnetic induction sensor through a microprocessor. The specific implementation method is as follows:

[0060] I. Unified Coordination and Control Logic:

[0061] 1. Digital-to-Analog Converter Control: The initialization and reset of the analog-to-digital converter U2 are controlled by setting the start and reset signals output by the pin; at the same time, the CS# (chip select) and SCLK (clock) signals of the SPI interface are used to trigger the analog-to-digital converter U2 to enter the working state, ensuring that it completes the analog-to-digital conversion in sequence.

[0062] 2. Low power consumption control of magnetic induction sensor: By setting the output control signal of the pin (such as high and low level switching), the MV2 magnetic sensor is triggered to enter the low power consumption mode (non-measurement period), reducing the overall power consumption of the system, and the sensor is only woken up to work during the measurement cycle;

[0063] II. Signal Acquisition and Data Processing:

[0064] 1. SPI Interface Data Acquisition: Communicates with the analog-to-digital converter U2 via the SPI bus to acquire the magnetic induction intensity component signal and temperature signal after analog-to-digital conversion in real time;

[0065] 2. Calculation and logical judgment: Process the collected temperature data and compare it with the preset optimal operating temperature threshold (e.g., 20-25℃): If the temperature is lower than the lower limit of the threshold, it is determined that the temperature needs to be increased; if the temperature is higher than the upper limit of the threshold, it is determined that the temperature needs to be decreased; if it is within the threshold range, maintain the current state.

[0066] III. Thermal management circuit control execution:

[0067] 1. Peltier element temperature regulation: Based on the temperature judgment result, the control signal is output to the IN1 and IN2 pins of the Peltier driver chip through the setting pin. When heating is required, the combination of IN1 and IN2 levels is controlled to make the Peltier element work in heating mode (current forward); when cooling is required, the IN1 and IN2 levels are switched to make the Peltier element work in cooling mode (current reverse).

[0068] 2. Cooling fan speed adjustment: The operation of the cooling fan is controlled by outputting a PWM signal through the setting pin, which absorbs excess cold or hot air generated by the operation of the Peltier element and keeps the ambient temperature of the MV2 magnetic sensor stable within the target range.

[0069] IV. System Closed-Loop Control and Stability Assurance:

[0070] The microprocessor continuously monitors the temperature signal of the MV2 magnetic sensor by periodically executing the "acquisition-judgment-control" process, and dynamically adjusts the Peltier mode and fan speed. At the same time, it uploads the processed magnetic induction intensity data to the host computer via USB communication to realize real-time monitoring of the measurement data.

[0071] In summary, the magnetic induction intensity measurement circuit provided by this utility model has a precise and reliable structure, stable logic control, and accurate and efficient measurement. It has strong practicality and effectively ensures the measurement accuracy of magnetic induction intensity. It is especially suitable for high-precision measurement scenarios, such as magnetic field measurement of TMS therapy devices. Of course, it can also be widely used in other magnetic field measurement fields.

[0072] The above are merely specific embodiments of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. A magnetic flux density measuring circuit, characterized in that, include: The magnetic field measurement circuit includes a magnetic induction sensor for detecting and outputting a set magnetic induction intensity signal and an internal temperature signal. The analog-to-digital conversion circuit includes an analog-to-digital converter, which receives the magnetic induction intensity signal and temperature signal output by the magnetic induction sensor and converts them into corresponding digital signals for output; The control circuit, including a microprocessor, is used to receive the converted magnetic induction intensity signal and temperature signal, and output corresponding control signals to the magnetic field measurement circuit, the analog-to-digital conversion circuit and the temperature management circuit. A temperature management circuit includes a Peltier element and a Peltier driving circuit, wherein the Peltier element is attached to a magnetic induction sensor, and the Peltier driving circuit is used to drive the Peltier element according to the Peltier control signal output by the microprocessor, thereby realizing the operating temperature control of the magnetic induction sensor. A power conversion circuit is used to provide the operating voltage.

2. The magnetic induction intensity measuring circuit according to claim 1, characterized in that, Also includes: The serial communication circuit includes an external communication interface and a protocol conversion circuit. The microprocessor connects to the external communication interface via the protocol conversion circuit to achieve data transmission.

3. The magnetic induction intensity measuring circuit according to claim 1, characterized in that, The power conversion circuit includes a linear regulator circuit and an LED indicator circuit. The linear regulator circuit is used to convert the externally input +5V voltage into a stable +3.3V voltage output, and the LED indicator circuit is used to display the operating status of the +3.3V voltage.

4. The magnetic induction intensity measuring circuit according to claim 1, characterized in that, The magnetic induction sensor has three orthogonally distributed Hall sensors built in, which can simultaneously measure the magnetic induction intensity signal in three orthogonal directions.

5. The magnetic induction intensity measuring circuit according to claim 4, characterized in that, The magnetic field measurement circuit also includes a DIP switch. The configuration pin of the magnetic induction sensor is connected to a high level through the DIP switch. The level of the configuration pin is controlled by turning the DIP switch on and off, thereby controlling the measurement range and measurement direction of the magnetic induction sensor.

6. The magnetic induction intensity measuring circuit according to claim 1, characterized in that, The magnetic field measurement circuit also includes a low-power control circuit, which is used to control the low-power mode of the magnetic induction sensor according to the low-power control signal output by the microprocessor.

7. The magnetic induction intensity measuring circuit according to claim 6, characterized in that, The low-power control circuit includes a transistor Q2 and a field-effect transistor Q1. The low-power output pin of the microprocessor is connected to the base of transistor Q2 through resistor R39. The base of transistor Q2 is grounded through resistor R41. The collector of transistor Q2 is connected to +5V through resistor R40, and its emitter is grounded. The source of field-effect transistor Q1 is connected to +5V. Its gate is connected to the collector of transistor Q2 through resistor R42, and its drain is connected to the low-power input pin of the magnetic induction sensor.

8. The magnetic induction intensity measuring circuit according to claim 1, characterized in that, The Peltier drive circuit includes a Peltier socket and a Peltier drive chip. The Peltier drive chip is used to output a corresponding Peltier drive signal to the Peltier socket according to the Peltier control signal output by the microprocessor. The Peltier socket is used to connect the Peltier element and output a corresponding Peltier drive signal to the Peltier element.

9. The magnetic induction intensity measuring circuit according to claim 1, characterized in that, The temperature management circuit also includes a cooling fan and a cooling fan control circuit, wherein the cooling fan is positioned toward the Peltier element, and the cooling fan control circuit is used to drive the cooling fan according to the fan control signal output by the microprocessor, thereby realizing the heat dissipation control of the Peltier element.

10. The magnetic induction intensity measuring circuit according to claim 9, characterized in that, The cooling fan control circuit includes a fan socket for connecting a cooling fan and for driving and controlling the cooling fan based on the PWM signal output by the microprocessor.

Images