STM32实现LM19温度精准测量

参考资料

ADC采样:

【stm32-hal】ADC模拟-数字转换技术

电压转温度公式：

LM19温度传感器数据手册

一、LM19核心要点

1. 供电：2.7~ 5.5V可测-55~ +130℃；2.4~ 2.7V仅-30~+130℃，STM32常用3.3V供电
2. 输出 ：模拟电压信号，温度越高输出电压越小
   抛物线公式： V O = − 3.88 × 10 − 6 T 2 − 0.0115 T + 1.8639 V_O=-3.88×10^{-6}T^2-0.0115T+1.8639 VO=−3.88×10−6T2−0.0115T+1.8639
   测温反推： T = − 1481.96 + 2.1962 × 10 6 + 1.8639 − V O 3.88 × 10 − 6 T=-1481.96+\sqrt{2.1962×10^6+\frac{1.8639-V_O}{3.88×10^{-6}}} T=−1481.96+2.1962×106+3.88×10−61.8639−VO
3. 引脚(TO92) ：1=VCC、2=VOUT、3=GND
   

二、硬件接线

LM19引脚	STM32	备注
V+(1脚)	3.3V	严禁5V超压可选
GND(3脚)	GND	共地
VOUT(2脚)	STM32 ADC输入引脚(PA0/PA1等)
外围推荐：电源端加0.1μF去耦电容；长线干扰大时：VOUT串200Ω+1μF到GND滤波

注意：LM19最大输出约2.485V(-55℃)＜3.3V，可直接接入3.3V量程ADC

三、STM32软件思路（HAL库为例）

1.配置

1. 开启ADC时钟，配置IO为模拟输入
2. ADC配置：单次/连续转换、12位分辨率、内部参考电压3.3V
3. ADC采样值换算电压：
   V o u t ( V ) = A D C v a l × 3.3 4095 V_{out}(V)=\frac{ADC_{val}×3.3}{4095} Vout(V)=4095ADCval×3.3

2.关键代码逻辑

//1.ADC读取原始值
uint16_t adc_val=HAL_ADC_GetValue(&hadc1);
//2.换算输出电压(V)
float Vo = adc_val * 3.3f / 4095.0f;
//3.带入LM19反算公式求温度
float temp = -1481.96f + sqrt(2196200.0f + (1.8639f-Vo)/3.88e-6f);

3.简化方案（小量程近似线性）

-30~100℃适用： V O = − 0.01177 × T + 1.8605 V_O = -0.01177×T+1.8605 VO=−0.01177×T+1.8605

T = ( 1.8605 − V O ) / 0.01177 T=(1.8605-V_O)/0.01177 T=(1.8605−VO)/0.01177

计算简单、单片机运算快，日常测温优先用此式。

四、误差优化

1. 采样滤波：连续采10~20次ADC取平均，降低噪声
2. 自发热忽略：LM19静态电流≤10μA，自升温＜0.02℃，无需补偿
3. 电源稳压：STM32 3.3V不稳会带来ADC误差，必要时校准ADC参考电压

五、示例：常用温度对照(快速校验)

温度	Vo电压
0℃	1.8639V
25℃	1.574V
30℃	1.515V
100℃	0.675V

六、代码

根据【stm32-hal】ADC模拟-数字转换技术中配置ADC

1. main()

/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "adc.h"
#include "gpio.h"
#include <math.h>

/* Private includes ----------------------------------------------------------*/


/**
  * @brief  The application entry point.
  * @retval int
  */
	int value = 0;
	float voltage =0.0;
	float temp =0.0;

//ADC多次采样平均值，times：采样次数
uint16_t Get_Adc_Average(uint8_t times)
{
    uint32_t adc_sum = 0;
    for(uint8_t i=0; i<times; i++)
    {
       // HAL_ADC_PollForConversion(&hadc1,HAL_MAX_DELAY);//已开启连续转换模式，只用写一次，可注释
        adc_sum += HAL_ADC_GetValue(&hadc1);
    }
    return adc_sum / times;
}

//LM19电压转温度
float LM19_GetTemp(float Vo)
{
    return -1481.96f + sqrtf(2196200.0f + (1.8639f - Vo)/3.88e-6f);
}

	
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_ADC1_Init();
  /* USER CODE BEGIN 2 */
	HAL_ADCEx_Calibration_Start(&hadc1);
	HAL_ADC_Start(&hadc1);
	HAL_ADC_PollForConversion(&hadc1,HAL_MAX_DELAY);
  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
    /* USER CODE END WHILE */
    value = Get_Adc_Average(20);  //20次平均
    voltage = value * 3.3f / 4095.0f;
    temp = LM19_GetTemp(voltage);
    /* USER CODE BEGIN 3 */
  }
  /* USER CODE END 3 */
}

2. adc.c

/* Includes ------------------------------------------------------------------*/
#include "adc.h"

/* USER CODE BEGIN 0 */

/* USER CODE END 0 */

ADC_HandleTypeDef hadc1;

/* ADC1 init function */
void MX_ADC1_Init(void)
{

  /* USER CODE BEGIN ADC1_Init 0 */

  /* USER CODE END ADC1_Init 0 */

  ADC_ChannelConfTypeDef sConfig = {0};

  /* USER CODE BEGIN ADC1_Init 1 */

  /* USER CODE END ADC1_Init 1 */

  /** Common config
  */
  hadc1.Instance = ADC1;
  hadc1.Init.ScanConvMode = ADC_SCAN_DISABLE;
  hadc1.Init.ContinuousConvMode = ENABLE;
  hadc1.Init.DiscontinuousConvMode = DISABLE;
  hadc1.Init.ExternalTrigConv = ADC_SOFTWARE_START;
  hadc1.Init.DataAlign = ADC_DATAALIGN_RIGHT;
  hadc1.Init.NbrOfConversion = 1;
  if (HAL_ADC_Init(&hadc1) != HAL_OK)
  {
    Error_Handler();
  }

  /** Configure Regular Channel
  */
  sConfig.Channel = ADC_CHANNEL_15;
  sConfig.Rank = ADC_REGULAR_RANK_1;
  sConfig.SamplingTime = ADC_SAMPLETIME_1CYCLE_5;
  if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN ADC1_Init 2 */

  /* USER CODE END ADC1_Init 2 */

}

void HAL_ADC_MspInit(ADC_HandleTypeDef* adcHandle)
{

  GPIO_InitTypeDef GPIO_InitStruct = {0};
  if(adcHandle->Instance==ADC1)
  {
  /* USER CODE BEGIN ADC1_MspInit 0 */

  /* USER CODE END ADC1_MspInit 0 */
    /* ADC1 clock enable */
    __HAL_RCC_ADC1_CLK_ENABLE();

    __HAL_RCC_GPIOC_CLK_ENABLE();
    /**ADC1 GPIO Configuration
    PC5     ------> ADC1_IN15
    */
    GPIO_InitStruct.Pin = GPIO_PIN_5;
    GPIO_InitStruct.Mode = GPIO_MODE_ANALOG;
    HAL_GPIO_Init(GPIOC, &GPIO_InitStruct);

  /* USER CODE BEGIN ADC1_MspInit 1 */

  /* USER CODE END ADC1_MspInit 1 */
  }
}

void HAL_ADC_MspDeInit(ADC_HandleTypeDef* adcHandle)
{

  if(adcHandle->Instance==ADC1)
  {
  /* USER CODE BEGIN ADC1_MspDeInit 0 */

  /* USER CODE END ADC1_MspDeInit 0 */
    /* Peripheral clock disable */
    __HAL_RCC_ADC1_CLK_DISABLE();

    /**ADC1 GPIO Configuration
    PC5     ------> ADC1_IN15
    */
    HAL_GPIO_DeInit(GPIOC, GPIO_PIN_5);

  /* USER CODE BEGIN ADC1_MspDeInit 1 */

  /* USER CODE END ADC1_MspDeInit 1 */
  }
}

/* USER CODE BEGIN 1 */

/* USER CODE END 1 */

3. 时钟配置

将原来的

void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

  /** 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.HSEPredivValue = RCC_HSE_PREDIV_DIV1;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
  RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;
  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();
  }
}

改成

void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
  RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};

  /** 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.HSEPredivValue = RCC_HSE_PREDIV_DIV1;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
  RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;
  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();
  }
  PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_ADC;
  PeriphClkInit.AdcClockSelection = RCC_ADCPCLK2_DIV6;//ADCPrescaler = DIV6 → ADC_CLK=72/6=12MHz
  if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
  {
    Error_Handler();
  }
}

否则，测到的电压偏大，温度偏低

核心原因：ADC时钟变了 → ADC采样精度变 → 电压算错 → 温度飘

STM32F1 ADC最大时钟不能超过14MHz，这是关键限制：

1、原来配置

ADCPrescaler = DIV2
SYSCLK=HSE*9=72M → APB2=72M → ADC_CLK =72/2=36MHz

超标(>14M)，ADC工作异常、采样跳变不准，温度乱飘。

2、修改后

ADCPrescaler = DIV6 → ADC_CLK=72/6=12MHz

12MHz＜14MHz，ADC进入标准正常工作区间，采样真实电压，温度自然变准。

快速总结

1. DIV2：36M超规格 → ADC采样失真，温度错误
2. DIV6：12M合规 → ADC读数真实，温度正确

配套优化（进一步稳温度）

ADC采样时间从1.5cycle改成长采样：

sConfig.SamplingTime = ADC_SAMPLETIME_239CYCLES_5;

七、现象

打开调试器可以观察到，temp等数据在不断变化。