STM32 I2C访问配置霍尔磁角度传感器MT6701
电机运转时，可以通过编码器/霍尔磁角度传感器如MT6701获取角度和位置以及计算出转速等信息。MT6701芯片应用需采用径向充磁的圆磁铁固定于电机轴侧面，将芯片感应中心对准磁铁进行测量。
MT6701具有多种输出模式，需要先通过I2C总线进行模式配置，然后再进行输出数据的解析。而MT6701的管脚具有复用特性，需要先进行模式的配置，才能使用I2C访问方式。
模式控制简单总结如下：
- 采用I2C访问方式， MODE管脚拉到高电平，Z管脚为输入管脚，拉到高电平
- 采用SSI访问方式，MODE管脚拉到高电平，Z管脚为输入管脚，拉到低电平（SSI片选有效），然后控制端发送SSI时钟信号（B管脚）并获得SSI数据（A管脚）
- 采用ABZ/ABN访问方式，MODE管脚拉到低电平，此时Z管脚为输出管脚
这里介绍采用TM32CUBEIDE开发环境，及STM32F401RCT6访问配置MT6701的过程。
STM32硬件接口配置
首先进行STM32CUBEIDE的工程配置，建立新的工程并配置时钟和接口：
48MHz时钟是配置给USB VCOM所用，先要进行USB VCOM配置：
USB VCOM的配置使用也可以参考《STM32 USB VCOM和HID的区别，配置及Echo功能实现（HAL）》
然后选择两个GPIO连接到MODE管脚和Z管脚，并初始化为高电平输出：
配置硬件I2C：
保存并产生基本工程代码：
MT6701 I2C访问寄存器
MT6701的I2C访问7 bit地址为二进制0000110。 0x03和0x04寄存器里存放可读取角度信息：
MT6701的控制寄存器组定义：
MT6701有一个OUT管脚，可以配置为模拟输出或PWM输出。本例将OUT管脚配置为PWM角度输出据输出。而主功能模式输出为ABZ模式。
PWM角度数据的STM32检测解析参考：《STM32解析霍尔磁角度传感器PWM脉冲角度数据》
AB数据的STM32检测解析参考：《STM32解析霍尔磁角度传感器AB脉冲数据》
对于一些电机驱动芯片（如TMC系列步进电机驱动芯片）支持ABZ/ABN解析, 则将三个信号直接连接到电机驱动芯片。
MT6701自带EEPROM保存功能，通过如下的指令可以将当前配置保存到非易失存储，并在重新上电后被读取应用：
STM32功能规划
本例程将实现如下功能：
- 通过USB VCOM可以发送十六进制单字节命令到STM32
- 发送0x01时通过I2C读取当前电机轴的角度位置信息
- 发送0x02时通过I2C配置MT6701在ABZ模式的工作参数（非差分ABZ输出，角度增加方向，一圈发出200个脉冲，OUT较为PWM输出模式，PWM输出频率选择等等）
- 发送0x03时将MT6701的配置烧录进EEPROM
重启系统后（MODE管脚拉到低电平），MT6701将输出ABZ数据和PWM角度数据。
STM32工程代码
首先设置USB VCOM接收串口指令：
c
static int8_t CDC_Receive_FS(uint8_t* Buf, uint32_t *Len)
{
/* USER CODE BEGIN 6 */
extern uint8_t ucmd;
ucmd = Buf[0];
USBD_CDC_SetRxBuffer(&hUsbDeviceFS, &Buf[0]);
USBD_CDC_ReceivePacket(&hUsbDeviceFS);
return (USBD_OK);
/* USER CODE END 6 */
}在main.c文件里实现全部的控制逻辑：
c
/* USER CODE BEGIN Header */
/**
******************************************************************************
* @file : main.c
* @brief : Main program body
******************************************************************************
* @attention
*
* Copyright (c) 2026 STMicroelectronics.
* All rights reserved.
*
* This software is licensed under terms that can be found in the LICENSE file
* in the root directory of this software component.
* If no LICENSE file comes with this software, it is provided AS-IS.
*
******************************************************************************
*/
//For i2c access
//Pin "mode" = high
//Pin "SSI CS = high
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "usb_device.h"
/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include "string.h"
/* USER CODE END Includes */
/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */
__IO float semiusDelayBase = 0;
void PY_semiusDelayTest(void)
{
__IO uint32_t firstms, secondms;
__IO uint32_t counter = 0;
firstms = HAL_GetTick()+1;
secondms = firstms+1;
while(uwTick!=firstms) ;
while(uwTick!=secondms) counter++;
semiusDelayBase = ((float)counter)/2000;
}
void PY_Delay_semius_t(uint32_t Delay)
{
__IO uint32_t delayReg;
__IO uint32_t semiusNum = (uint32_t)(Delay*semiusDelayBase);
delayReg = 0;
while(delayReg!=semiusNum) delayReg++;
}
void PY_semiusDelayOptimize(void)
{
__IO uint32_t firstms, secondms;
__IO float coe = 1.0;
firstms = HAL_GetTick();
PY_Delay_semius_t(2000000) ;
secondms = HAL_GetTick();
coe = ((float)1000)/(secondms-firstms);
semiusDelayBase = coe*semiusDelayBase;
}
void PY_Delay_semius(uint32_t Delay)
{
__IO uint32_t delayReg;
uint32_t msNum = Delay/2000;
uint32_t semiusNum = (uint32_t)((Delay%2000)*semiusDelayBase);
if(msNum>0) HAL_Delay(msNum);
delayReg = 0;
while(delayReg!=semiusNum) delayReg++;
}
void PY_Delay_us_t(uint32_t Delay)
{
PY_Delay_semius_t(Delay*2);
}
void PY_Delay_ms_t(uint32_t Delay)
{
PY_Delay_us_t(Delay*1000);
}
/* USER CODE END PTD */
/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */
/*
*Convert float to string type
*Written by Pegasus Yu in 2022
*stra: string address as mychar from char mychar[];
*float: float input like 12.345
*flen: fraction length as 3 for 12.345
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>
void py_f2s4printf(char * stra, float x, uint8_t flen)
{
uint32_t base;
int64_t dn;
char mc[32];
base = pow(10,flen);
dn = x*base;
sprintf(stra, "%d.", (int)(dn/base));
dn = abs(dn);
if(dn%base==0)
{
for(uint8_t j=1;j<=flen;j++)
{
stra = strcat(stra, "0");
}
return;
}
else
{
if(flen==1){
sprintf(mc, "%d", (int)(dn%base));
stra = strcat(stra, mc);
return;
}
for(uint8_t j=1;j<flen;j++)
{
if((dn%base)<pow(10,j))
{
for(uint8_t k=1;k<=(flen-j);k++)
{
stra = strcat(stra, "0");
}
sprintf(mc, "%d", (int)(dn%base));
stra = strcat(stra, mc);
return;
}
}
sprintf(mc, "%d", (int)(dn%base));
stra = strcat(stra, mc);
return;
}
}
/* USER CODE END PD */
/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */
uint8_t CDC_Transmit_FS(uint8_t* Buf, uint16_t Len);
/* USER CODE END PM */
/* Private variables ---------------------------------------------------------*/
I2C_HandleTypeDef hi2c1;
/* USER CODE BEGIN PV */
/* USER CODE END PV */
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_I2C1_Init(void);
/* USER CODE BEGIN PFP */
uint8_t i2c1_data_tx[16];
uint8_t i2c1_data_rx[16];
uint8_t UVW_MUX;
uint8_t ABZ_MUX;
uint8_t DIR;
uint8_t OUTPUT_MODE;
uint16_t ABZ_RES;
uint8_t HYST;
uint8_t ZPW;
uint8_t ZL;
uint8_t PWMF;
uint16_t I2C_Angle_Read= 0 ;
float I2C_Angle_F= 0.0 ;
/* USER CODE END PFP */
/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
uint8_t ucmd = 0;
char mychar[50];
char str0[80];
char * str1;
/* USER CODE END 0 */
/**
* @brief The application entry point.
* @retval int
*/
int main(void)
{
/* USER CODE BEGIN 1 */
/* USER CODE END 1 */
/* MCU Configuration--------------------------------------------------------*/
/* Reset of all peripherals, Initializes the Flash interface and the Systick. */
HAL_Init();
/* USER CODE BEGIN Init */
/* USER CODE END Init */
/* Configure the system clock */
SystemClock_Config();
/* USER CODE BEGIN SysInit */
/* USER CODE END SysInit */
/* Initialize all configured peripherals */
MX_GPIO_Init();
MX_I2C1_Init();
MX_USB_DEVICE_Init();
/* USER CODE BEGIN 2 */
PY_semiusDelayTest();
PY_semiusDelayOptimize();
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
if(ucmd == 0x01) //Read I2C angle
{
ucmd = 0;
I2C_Angle_Read = 0;
i2c1_data_tx[0] = 0x03;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 1, 2700);
HAL_I2C_Master_Receive(&hi2c1, 0x0c, i2c1_data_rx, 1, 2700);
I2C_Angle_Read = (i2c1_data_rx[0]<<6);
i2c1_data_tx[0] = 0x04;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 1, 2700);
HAL_I2C_Master_Receive(&hi2c1, 0x0c, i2c1_data_rx, 1, 2700);
I2C_Angle_Read += (i2c1_data_rx[0] & 0x3F);
I2C_Angle_F = (((float)I2C_Angle_Read)/16384)*360;
py_f2s4printf(mychar, I2C_Angle_F, 2);
sprintf(str0, "\r\nCurrent Degree = %s °\r\n", mychar);
CDC_Transmit_FS((uint8_t *)str0, strlen(str0));
}
else if(ucmd == 0x02)
{
ucmd = 0;
//Set to ABZ NON-DIFFERENTIAL OUTPUT MODE
i2c1_data_tx[0] = 0x25;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 1, 2700);
HAL_I2C_Master_Receive(&hi2c1, 0x0c, i2c1_data_rx, 1, 2700);
UVW_MUX = i2c1_data_rx[0];
i2c1_data_tx[1] = UVW_MUX&0x7F;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 2, 2700);
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 1, 2700);
HAL_I2C_Master_Receive(&hi2c1, 0x0c, i2c1_data_rx, 1, 2700);
UVW_MUX = i2c1_data_rx[0];
i2c1_data_tx[0] = 0x29;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 1, 2700);
HAL_I2C_Master_Receive(&hi2c1, 0x0c, i2c1_data_rx, 1, 2700);
ABZ_MUX = i2c1_data_rx[0];
i2c1_data_tx[1] = ABZ_MUX&0xBF;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 2, 2700);
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 1, 2700);
HAL_I2C_Master_Receive(&hi2c1, 0x0c, i2c1_data_rx, 1, 2700);
ABZ_MUX = i2c1_data_rx[0];
//Set relationship of direction and degree-increasing
i2c1_data_tx[0] = 0x29;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 1, 2700);
HAL_I2C_Master_Receive(&hi2c1, 0x0c, i2c1_data_rx, 1, 2700);
DIR = i2c1_data_rx[0];
#if 1
i2c1_data_tx[1] = DIR|0x02; //Set to 1
#else
i2c1_data_tx[1] = DIR&0xFD; //Set to 0
#endif
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 2, 2700);
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 1, 2700);
HAL_I2C_Master_Receive(&hi2c1, 0x0c, i2c1_data_rx, 1, 2700);
DIR = i2c1_data_rx[0];
//Set ABZ to 200 pulses per circle
uint16_t ppc = 0x00C7;
i2c1_data_tx[0] = 0x31; i2c1_data_tx[1] = (uint8_t)ppc;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 2, 2700);
i2c1_data_tx[0] = 0x30; i2c1_data_tx[1] = (ppc>>8) & 0x03;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 2, 2700);
i2c1_data_tx[0] = 0x30;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 1, 2700);
HAL_I2C_Master_Receive(&hi2c1, 0x0c, i2c1_data_rx, 1, 2700);
ABZ_RES = i2c1_data_rx[0];
ABZ_RES <<= 8;
i2c1_data_tx[0] = 0x31;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 1, 2700);
HAL_I2C_Master_Receive(&hi2c1, 0x0c, i2c1_data_rx, 1, 2700);
ABZ_RES |= i2c1_data_rx[0];
//Set HYST to 0
i2c1_data_tx[0] = 0x32;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 1, 2700);
HAL_I2C_Master_Receive(&hi2c1, 0x0c, i2c1_data_rx, 1, 2700);
HYST = i2c1_data_rx[0];
HYST &= 0x7F;
i2c1_data_tx[1] = HYST;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 2, 2700);
i2c1_data_tx[0] = 0x34;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 1, 2700);
HAL_I2C_Master_Receive(&hi2c1, 0x0c, i2c1_data_rx, 1, 2700);
HYST = i2c1_data_rx[0];
HYST &= 0x3F;
i2c1_data_tx[1] = HYST;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 2, 2700);
//Set Z_pulse width to 1LSB
i2c1_data_tx[0] = 0x32;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 1, 2700);
HAL_I2C_Master_Receive(&hi2c1, 0x0c, i2c1_data_rx, 1, 2700);
ZPW = i2c1_data_rx[0];
ZPW &= 0x8F;
i2c1_data_tx[1] = ZPW;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 2, 2700);
//Set Zero location
i2c1_data_tx[0] = 0x32;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 1, 2700);
HAL_I2C_Master_Receive(&hi2c1, 0x0c, i2c1_data_rx, 1, 2700);
ZL = i2c1_data_rx[0];
ZL &= 0xF0;
i2c1_data_tx[1] = ZL;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 2, 2700);
i2c1_data_tx[0] = 0x33;
i2c1_data_tx[1] = 0;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 2, 2700);
//Set PWM frequency to 994.4Hz
i2c1_data_tx[0] = 0x38;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 1, 2700);
HAL_I2C_Master_Receive(&hi2c1, 0x0c, i2c1_data_rx, 1, 2700);
PWMF = i2c1_data_rx[0];
PWMF &= 0x7F;
i2c1_data_tx[1] = PWMF;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 2, 2700);
//Set PWM POL to high
i2c1_data_tx[0] = 0x38;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 1, 2700);
HAL_I2C_Master_Receive(&hi2c1, 0x0c, i2c1_data_rx, 1, 2700);
PWMF = i2c1_data_rx[0];
PWMF &= 0xBF;
i2c1_data_tx[1] = PWMF;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 2, 2700);
//Set OUT_MODE to PWM
i2c1_data_tx[0] = 0x38;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 1, 2700);
HAL_I2C_Master_Receive(&hi2c1, 0x0c, i2c1_data_rx, 1, 2700);
OUTPUT_MODE = i2c1_data_rx[0];
OUTPUT_MODE |= 020;
i2c1_data_tx[1] = OUTPUT_MODE;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 2, 2700);
str1 = "\r\nConfig Done\r\n";
CDC_Transmit_FS((uint8_t *)str1, strlen(str1));
}
else if(ucmd == 0x03)
{
ucmd = 0;
i2c1_data_tx[0] = 0x09; i2c1_data_tx[1] = 0xb3;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 2, 2700);
i2c1_data_tx[0] = 0x0a; i2c1_data_tx[1] = 0x05;
HAL_I2C_Master_Transmit(&hi2c1, 0x0c, i2c1_data_tx, 2, 2700);
PY_Delay_us_t(1000000);
str1 = "\r\nEEPROM PROGRAMMED\r\n";
CDC_Transmit_FS((uint8_t *)str1, strlen(str1));
}
else PY_Delay_us_t(10);
/* USER CODE END WHILE */
/* USER CODE BEGIN 3 */
}
/* USER CODE END 3 */
}
/**
* @brief System Clock Configuration
* @retval None
*/
void SystemClock_Config(void)
{
RCC_OscInitTypeDef RCC_OscInitStruct = {0};
RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
/** Configure the main internal regulator output voltage
*/
__HAL_RCC_PWR_CLK_ENABLE();
__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE2);
/** Initializes the RCC Oscillators according to the specified parameters
* in the RCC_OscInitTypeDef structure.
*/
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
RCC_OscInitStruct.HSEState = RCC_HSE_ON;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLM = 25;
RCC_OscInitStruct.PLL.PLLN = 336;
RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV4;
RCC_OscInitStruct.PLL.PLLQ = 7;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
Error_Handler();
}
/** Initializes the CPU, AHB and APB buses clocks
*/
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
{
Error_Handler();
}
}
/**
* @brief I2C1 Initialization Function
* @param None
* @retval None
*/
static void MX_I2C1_Init(void)
{
/* USER CODE BEGIN I2C1_Init 0 */
/* USER CODE END I2C1_Init 0 */
/* USER CODE BEGIN I2C1_Init 1 */
/* USER CODE END I2C1_Init 1 */
hi2c1.Instance = I2C1;
hi2c1.Init.ClockSpeed = 100000;
hi2c1.Init.DutyCycle = I2C_DUTYCYCLE_2;
hi2c1.Init.OwnAddress1 = 0;
hi2c1.Init.AddressingMode = I2C_ADDRESSINGMODE_7BIT;
hi2c1.Init.DualAddressMode = I2C_DUALADDRESS_DISABLE;
hi2c1.Init.OwnAddress2 = 0;
hi2c1.Init.GeneralCallMode = I2C_GENERALCALL_DISABLE;
hi2c1.Init.NoStretchMode = I2C_NOSTRETCH_DISABLE;
if (HAL_I2C_Init(&hi2c1) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN I2C1_Init 2 */
/* USER CODE END I2C1_Init 2 */
}
/**
* @brief GPIO Initialization Function
* @param None
* @retval None
*/
static void MX_GPIO_Init(void)
{
GPIO_InitTypeDef GPIO_InitStruct = {0};
/* USER CODE BEGIN MX_GPIO_Init_1 */
/* USER CODE END MX_GPIO_Init_1 */
/* GPIO Ports Clock Enable */
__HAL_RCC_GPIOH_CLK_ENABLE();
__HAL_RCC_GPIOA_CLK_ENABLE();
__HAL_RCC_GPIOB_CLK_ENABLE();
/*Configure GPIO pin Output Level */
HAL_GPIO_WritePin(GPIOB, MODE_I2C_Pin|Z_SSICS_Pin, GPIO_PIN_SET);
/*Configure GPIO pins : MODE_I2C_Pin Z_SSICS_Pin */
GPIO_InitStruct.Pin = MODE_I2C_Pin|Z_SSICS_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
/* USER CODE BEGIN MX_GPIO_Init_2 */
/* USER CODE END MX_GPIO_Init_2 */
}
/* USER CODE BEGIN 4 */
/* USER CODE END 4 */
/**
* @brief This function is executed in case of error occurrence.
* @retval None
*/
void Error_Handler(void)
{
/* USER CODE BEGIN Error_Handler_Debug */
/* User can add his own implementation to report the HAL error return state */
__disable_irq();
while (1)
{
}
/* USER CODE END Error_Handler_Debug */
}
#ifdef USE_FULL_ASSERT
/**
* @brief Reports the name of the source file and the source line number
* where the assert_param error has occurred.
* @param file: pointer to the source file name
* @param line: assert_param error line source number
* @retval None
*/
void assert_failed(uint8_t *file, uint32_t line)
{
/* USER CODE BEGIN 6 */
/* User can add his own implementation to report the file name and line number,
ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
/* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */其中，USB VCOM打印输出的浮点转字符串函数参考：《STM32 UART串口printf函数应用及浮点打印代码空间节省 (HAL)》
STM32工程代码测试
通过串口工具连接并进行测试：
