float voltage = adc_value * VREF / MAX_ADC_VALUE;什么意思

这段代码是将模拟转换器的输出值（ADC值）转换为电压值。其中，adc_value是模拟转换器的输出值，VREF是参考电压的值，MAX_ADC_VALUE是模拟转换器的最大输出值。该代码将adc_value乘以参考电压VREF并除以最大输出值MAX_ADC_VALUE，得到了电压值。最终结果以浮点数的形式存储在voltage变量中。

相关问题

基于NUCLEO-U575ZI-Q开发板使用ADC读取NTC电阻的温度的代码

下面是使用NUCLEO-U575ZI-Q开发板读取NTC电阻温度的ADC代码（假设NTC电阻与ADC引脚PA0相连）：

#include "stm32u5xx_hal.h"

ADC_HandleTypeDef hadc;

void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_ADC1_Init(void);

int main(void)
{
    HAL_Init();
    SystemClock_Config();
    MX_GPIO_Init();
    MX_ADC1_Init();

    while (1)
    {
        // 开始ADC转换
        HAL_ADC_Start(&hadc);
        // 等待转换完成
        HAL_ADC_PollForConversion(&hadc, HAL_MAX_DELAY);
        // 读取ADC值并计算温度（假设NTC电阻分压电阻为10kΩ，B值为3950K）
        uint16_t adc_value = HAL_ADC_GetValue(&hadc);
        float voltage = adc_value * 3.3 / 4096; // ADC参考电压为3.3V，分辨率为12位（4096个量化级别）
        float resistance = 10000 * voltage / (3.3 - voltage);
        float temperature = 1 / (1 / 298.15 + 1 / 3950 * log(resistance / 10000)) - 273.15;
        // 输出温度
        printf("Temperature: %.2f\n", temperature);
        // 延时一段时间
        HAL_Delay(1000);
    }
}

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

    /** Supply configuration update enable 
    */
    HAL_PWREx_ConfigSupply(PWR_LDO_SUPPLY);
    /** Configure the main internal regulator output voltage 
    */
    __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);

    while (!__HAL_PWR_GET_FLAG(PWR_FLAG_VOSRDY))
    {
    }
    /** Initializes the RCC Oscillators according to the specified parameters 
    * in the RCC_OscInitTypeDef structure.
    */
    RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI48 | RCC_OSCILLATORTYPE_HSI | RCC_OSCILLATORTYPE_LSE;
    RCC_OscInitStruct.HSIState = RCC_HSI_ON;
    RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
    RCC_OscInitStruct.LSEState = RCC_LSE_ON;
    RCC_OscInitStruct.HSI48State = RCC_HSI48_ON;
    RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
    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_HSI;
    RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
    RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
    RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
    if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
    {
        Error_Handler();
    }
}

static void MX_ADC1_Init(void)
{
    ADC_MultiModeTypeDef multimode = {0};
    ADC_ChannelConfTypeDef sConfig = {0};

    hadc.Instance = ADC1;
    hadc.Init.ClockPrescaler = ADC_CLOCK_ASYNC_DIV1;
    hadc.Init.Resolution = ADC_RESOLUTION_12B;
    hadc.Init.ScanConvMode = ADC_SCAN_DISABLE;
    hadc.Init.ContinuousConvMode = DISABLE;
    hadc.Init.DiscontinuousConvMode = DISABLE;
    hadc.Init.ExternalTrigConv = ADC_SOFTWARE_START;
    hadc.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_NONE;
    hadc.Init.DMAContinuousRequests = DISABLE;
    hadc.Init.Overrun = ADC_OVR_DATA_OVERWRITTEN;
    hadc.Init.SamplingTimeCommon1 = ADC_SAMPLETIME_640CYCLES_5;
    hadc.Init.SamplingTimeCommon2 = ADC_SAMPLETIME_640CYCLES_5;
    hadc.Init.OversamplingMode = DISABLE;
    hadc.Init.TriggerFrequencyMode = ADC_TRIGGER_FREQ_HIGH;
    hadc.Init.LowPowerAutoWait = DISABLE;
    hadc.Init.LowPowerFrequencyMode = DISABLE;
    hadc.Init.LowPowerAutoPowerOff = DISABLE;
    hadc.Init.ChannelsBank = ADC_CHANNELS_BANK_A;
    hadc.Init.VREF = ADC_VREF_INTERNAL;

    if (HAL_ADC_Init(&hadc) != HAL_OK)
    {
        Error_Handler();
    }

    multimode.Mode = ADC_MODE_INDEPENDENT;
    if (HAL_ADCEx_MultiModeConfigChannel(&hadc, &multimode) != HAL_OK)
    {
        Error_Handler();
    }

    sConfig.Channel = ADC_CHANNEL_0;
    sConfig.Rank = ADC_RANK_CHANNEL_NUMBER;
    sConfig.SamplingTime = ADC_SAMPLETIME_640CYCLES_5;
    sConfig.SingleDiff = ADC_SINGLE_ENDED;
    sConfig.OffsetNumber = ADC_OFFSET_NONE;
    sConfig.Offset = 0;

    if (HAL_ADC_ConfigChannel(&hadc, &sConfig) != HAL_OK)
    {
        Error_Handler();
    }
}

static void MX_GPIO_Init(void)
{
    GPIO_InitTypeDef GPIO_InitStruct = {0};

    /* GPIO Ports Clock Enable */
    __HAL_RCC_GPIOA_CLK_ENABLE();

    /*Configure GPIO pin : PA0 */
    GPIO_InitStruct.Pin = GPIO_PIN_0;
    GPIO_InitStruct.Mode = GPIO_MODE_ANALOG;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
}

MAX471测电流stm32f103c8t6代码详细一点

MAX471是一款电流传感器，可以用于测量路中的电流值。下面是一个基于STM32FC8T6的代码示例，用于使用MAX471测电流：

#include "stm32f10x.h"

// 定义ADC通道和引脚
#define ADC_CHANNEL GPIO_Pin_0
#define ADC_GPIO GPIOA

// 定义ADC外设
ADC_InitTypeDef ADC_InitStructure;

// 初始化ADC
void ADC_Init_Config(void)
{
    // 使能ADC1时钟
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE);

    // 配置ADC参数
    ADC_InitStructure.ADC_Mode = ADC_Mode_Independent;
    ADC_InitStructure.ADC_ScanConvMode = DISABLE;
    ADC_InitStructure.ADC_ContinuousConvMode = DISABLE;
    ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_None;
    ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
    ADC_InitStructure.ADC_NbrOfChannel = 1;

    // 初始化ADC
    ADC_Init(ADC1, &ADC_InitStructure);

    // 配置ADC通道
    ADC_RegularChannelConfig(ADC1, ADC_Channel_0, 1, ADC_SampleTime_55Cycles5);

    // 使能ADC1
    ADC_Cmd(ADC1, ENABLE);

    // 开启ADC校准
    ADC_ResetCalibration(ADC1);
    while (ADC_GetResetCalibrationStatus(ADC1))
        ;
    ADC_StartCalibration(ADC1);
    while (ADC_GetCalibrationStatus(ADC1))
        ;

    // 启动ADC转换
    ADC_SoftwareStartConvCmd(ADC1, ENABLE);
}

// 读取ADC值
uint16_t ADC_Read_Value(void)
{
    // 等待转换完成
    while (!ADC_GetFlagStatus(ADC1, ADC_FLAG_EOC))
        ;

    // 返回ADC值
    return ADC_GetConversionValue(ADC1);
}

// 计算电流值
float Calculate_Current(uint16_t adcValue, float vRef, float rSense)
{
    // 根据公式计算电流值
    float voltage = (adcValue * vRef) / 4096.0;
    float current = voltage / rSense;

    return current;
}

int main(void)
{
    // 初始化ADC
    ADC_Init_Config();

    // 设置参考电压和电阻值
    float vRef = 3.3;   // 参考电压为3.3V
    float rSense = 0.1; // 电阻值为0.1Ω

    while (1)
    {
        // 读取ADC值
        uint16_t adcValue = ADC_Read_Value();

        // 计算电流值
        float current = Calculate_Current(adcValue, vRef, rSense);

        // 在这里可以进行电流值的处理和输出

        // 延时一段时间
        for (int i = 0; i < 1000000; i++)
            ;
    }
}

这段代码使用了STM32的ADC模块来读取MAX471传感器的电流值。首先需要初始化ADC，并配置通道和采样时间。然后在主循环中，通过调用`ADC_Read_Value`函数读取ADC值，再通过`Calculate_Current`函数计算出电流值。你可以根据需要对电流值进行处理和输出。