stm32VREF–是什么电压

### STM32F103C8T6 ADC Voltage Read Example Code and Configuration For the STM32F103C8T6 microcontroller, configuring and using the Analog-to-Digital Converter (ADC) involves several steps including setting up the clock system, initializing GPIO pins connected to analog channels, enabling DMA or interrupts if necessary, and finally writing a function that reads from an ADC channel. The following is an example of how one might configure and use the ADC on this device: #### Hardware Initialization Firstly, it's important to initialize hardware resources such as clocks and GPIOs before starting any conversion process. The RCC must be configured properly so that peripherals like ADC can operate at their required frequencies[^1]. ```c // Enable peripheral clocks RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1 | RCC_APB2Periph_GPIOA, ENABLE); ``` #### ADC Channel Selection & Configuration Next comes selecting which pin will serve as input for our measurements along with its corresponding ADC channel number. In addition, settings related specifically to each individual channel need adjustment too – these include resolution mode selection among others[^2]. ```c GPIO_InitTypeDef GPIO_InitStructure; ADC_InitTypeDef ADC_InitStructure; /* Configure PA0 as analog input */ GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AIN; GPIO_Init(GPIOA, &GPIO_InitStructure); /* Initialize ADC structure parameters */ ADC_StructInit(&ADC_InitStructure); ADC_InitStructure.ADC_ScanConvMode = DISABLE; // Single-channel conversion ADC_InitStructure.ADC_ContinuousConvMode = DISABLE;// One-shot conversion ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right; ADC_InitStructure.ADC_NbrOfChannel = 1; ADC_Init(ADC1, &ADC_InitStructure); ``` #### Starting Conversion Process Once everything has been set correctly according to your needs then you may proceed by initiating conversions either through software trigger method calls provided within HAL libraries or directly manipulating registers depending upon what level of abstraction suits best during development phase.[^3] ```c // Start ADC calibration ADC_Cmd(ADC1, DISABLE); ADC_ResetCalibration(ADC1); while(ADC_GetResetCalibrationStatus(ADC1)); ADC_StartCalibration(ADC1); while(ADC_GetCalibrationStatus(ADC1)); // Enable ADC ADC_Cmd(ADC1, ENABLE); // Wait until ADON bit is reset while(ADC_GetFlagStatus(ADC1, ADC_FLAG_ADEN)==RESET); // Start single conversion ADC_SoftwareStartConvCmd(ADC1, ENABLE); ``` #### Reading Results Finally after all preparations have completed successfully we are ready now not only start but also obtain results produced out from performed operations above mentioned earlier hereafter:[^4] ```c uint16_t adcValue; adcValue = ADC_GetConversionValue(ADC1); float voltage = ((3.3f / 4095) * adcValue); // Assuming Vref=3.3V and 12-bit resolution ```

### STM32 NTC热敏电阻温度测量方法 在STM32平台上实现NTC热敏电阻的温度测量涉及硬件连接和软件编程两部分。对于所选的3380 10K NTC热敏电阻，在-40°C至+125°C范围内的性能表现良好[^1]。 #### 硬件连接方案 为了完成这一功能，通常会采用分压电路来接入NTC热敏电阻到STM32的模拟输入端口(ADC)，这样可以将NTC随温度变化产生的阻值变动转化为可被MCU读取的电压信号。具体来说，就是把NTC与固定电阻串联形成分压网络，一端接电源另一端接地，中间节点接到STM32的一个ADC通道上。 #### 软件算法原理 当完成了上述物理层面的设计之后，则需编写相应的程序来进行数据处理。核心在于利用预先给定的标准曲线或数学模型（比如Steinhart-Hart方程），根据实际测得的电压值得出对应的温度数值。这里给出了一种简化的方法： \[ R_{ntc}=\frac{Vcc \times R}{V-Vin}-R \] 其中\( Vcc \)代表供电电压； \( Vin \)表示由ADC转换得到的实际采样点处的瞬时电位差；而 \( R \)则是指外加于NTC上的已知标准电阻之大小。接着再依据制造商提供的参数表查找对应关系或是应用特定的经验公式求解最终的结果。 #### C代码实例展示 下面是一份基于STM32 HAL库编写的简单示例代码片段，展示了如何初始化ADC模块以及执行一次性的温度读数操作: ```c #include "stm32f1xx_hal.h" // 定义全局变量存储当前温度 float current_temperature; /** * @brief 初始化 ADC 配置. */ static void MX_ADC_Init(void){ /* USER CODE BEGIN ADC_Init 0 */ /* USER CODE END ADC_Init 0 */ ADC_ChannelConfTypeDef sConfig = {0}; // ... (省略了具体的初始化设置) } /** * @brief 获取 NTC 的原始 AD 值. */ uint32_t Get_NTCDetectValue(){ HAL_ADC_Start(&hadc); if(HAL_OK != HAL_ADC_PollForConversion(&hadc, 10)){ Error_Handler(); } return HAL_ADC_GetValue(&hadc); } /** * @brief 计算当前温度. */ void Calculate_Temperature(uint32_t adc_value){ const float vref = 3.3; const float r_fixed = 10000; // 固定电阻值为10kΩ float vin = ((adc_value / 4096.0)*vref); // 将AD值转成真实电压 float r_ntc = (r_fixed*(vref-vin))/vin; // 使用前面提到的公式计算NTC电阻 // 这里假设有一个函数可以根据电阻值查表获得温度， // 实际开发中可能需要用更精确的方式如 Steinhart–Hart 方程式。 current_temperature = LookupTable(r_ntc); } ``` 此段代码实现了从ADC获取NTC传感器的数据，并通过一定的运算得出近似的温度值。需要注意的是，`LookupTable()` 函数并未在此列出，它应该包含了针对特定型号NTC元件特性的映射逻辑。