使用 STM32L ADC 单独读取不同的输入

Question

目标是通过轮询读取多个 ADC 通道。它不需要很快——想法是读取所连接的不同电池的电压。我有一个 STM32L071 微控制器。与 STM32F0 模型相比，编程有点不同。我正在使用平台。

我在这里找到了非常有用的信息：

• Individually read distinct inputs with STM32F0 ADC
• https://controllerstech.com/stm32-adc-multiple-channels/
• https://deepbluembedded.com/stm32-adc-tutorial-complete-guide-with-examples/

但是，不幸的是我无法读出多个频道。这些问题可能与HAL_ADC_Init 和HAL_ADC_ConfigChannel 有关。

这是一个最小的代码示例：

#include <Arduino.h>
#include <STM32IntRef.h>

uint32_t a1=0, a2=0;

#define HAL_ADC_MODULE_ENABLED
ADC_HandleTypeDef hadc1;

void displaying(){
    Serial.println("values:");
    Serial.println("-------");
    Serial.print("ch1 - ");
    Serial.println(a1);
    Serial.print("ch2 - ");
    Serial.println(a2);
    Serial.println("");
}

void config_ext_channel_ADC(uint32_t channel, bool val) {
  hadc1.Instance = ADC1;
  hadc1.Init.SamplingTime = ADC_SAMPLETIME_79CYCLES_5;
  HAL_ADC_Init(&hadc1);
  
  ADC_ChannelConfTypeDef sConfig;
  sConfig.Channel = channel;
  if (val == true)  {
    sConfig.Rank = ADC_RANK_CHANNEL_NUMBER;
  } else {
    sConfig.Rank = ADC_RANK_NONE;
  }
  if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK) {
        Serial.println("Error ADC Config Channel");
        //Error_Handler();
  }
}

uint32_t r_single_ext_channel_ADC(uint32_t channel) {
  /* read the ADC and output result */
  uint32_t digital_result;
  config_ext_channel_ADC(channel, true);
  HAL_ADCEx_Calibration_Start(&hadc1, ADC_SINGLE_ENDED);
  HAL_ADC_Start(&hadc1);
  HAL_ADC_PollForConversion(&hadc1, 1000);
  digital_result = HAL_ADC_GetValue(&hadc1);
  HAL_ADC_Stop(&hadc1);
  config_ext_channel_ADC(channel, false);
  return digital_result;
}

void readBat() {
  /* read voltages */
  a1 = r_single_ext_channel_ADC(1);
  a2 = r_single_ext_channel_ADC(PA2);
}

void setup() {
  // put your setup code here, to run once:
  // Serial monitor
  Serial.begin(9600);
  Serial.println(F("Starting now"));
  // initialize pins for ADC
  analogReadResolution(ADC_RESOLUTION);
  pinMode(PA1, INPUT);
  //pinMode(BATTERY_SENSE_PIN2, INPUT);
  pinMode(PA2, INPUT_ANALOG);
}

void loop() {
  // put your main code here, to run repeatedly:
  readBat();
  displaying();
  delay(2000);
}

输出是：

values:
-------
ch1 - 0
ch2 - 140

听起来很合理，但在引脚上施加一些电压不会改变值。

有人可以给我一些建议，想法吗？

Answer 1

好的，与此同时我发现了问题。软件很好；我采用了 Arduino 框架并使用了analogRead()。

我需要清除 PCB 上的所有助焊剂，这些助焊剂会导致引脚之间发生一些接触。 此外，如果想直接使用 HAL 地址，则应设置 ClockDivider，使 ADC 采样频率低于 1 MHz。

Answer 2

分别读取不同 ADC 通道（这里是 ADC2 有 2 个通道）的代码（由 CubeMX 生成）：

注意：我们必须使用ScanConvMode加上DiscontinuousConvMode和NO ContinuousConvMode。

/* ADC2 init function */
void MX_ADC2_Init(void)
{

  /* USER CODE BEGIN ADC2_Init 0 */

  /* USER CODE END ADC2_Init 0 */

  ADC_ChannelConfTypeDef sConfig = {0};

  /* USER CODE BEGIN ADC2_Init 1 */

  /* USER CODE END ADC2_Init 1 */
  /** Configure the global features of the ADC (Clock, Resolution, Data Alignment and number of conversion)
  */
  hadc2.Instance = ADC2;
  hadc2.Init.ClockPrescaler = ADC_CLOCK_SYNC_PCLK_DIV4;
  hadc2.Init.Resolution = ADC_RESOLUTION_12B;
  hadc2.Init.ScanConvMode = ENABLE;
  hadc2.Init.ContinuousConvMode = DISABLE;
  hadc2.Init.DiscontinuousConvMode = ENABLE;
  hadc2.Init.NbrOfDiscConversion = 1;
  hadc2.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_NONE;
  hadc2.Init.ExternalTrigConv = ADC_SOFTWARE_START;
  hadc2.Init.DataAlign = ADC_DATAALIGN_RIGHT;
  hadc2.Init.NbrOfConversion = 2;
  hadc2.Init.DMAContinuousRequests = DISABLE;
  hadc2.Init.EOCSelection = ADC_EOC_SINGLE_CONV;
  if (HAL_ADC_Init(&hadc2) != HAL_OK)
  {
    Error_Handler();
  }
  /** Configure for the selected ADC regular channel its corresponding rank in the sequencer and its sample time.
  */
  sConfig.Channel = ADC_CHANNEL_8;
  sConfig.Rank = 1;
  sConfig.SamplingTime = ADC_SAMPLETIME_480CYCLES;
  if (HAL_ADC_ConfigChannel(&hadc2, &sConfig) != HAL_OK)
  {
    Error_Handler();
  }
  /** Configure for the selected ADC regular channel its corresponding rank in the sequencer and its sample time.
  */
  sConfig.Channel = ADC_CHANNEL_9;
  sConfig.Rank = 2;
  if (HAL_ADC_ConfigChannel(&hadc2, &sConfig) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN ADC2_Init 2 */

  /* USER CODE END ADC2_Init 2 */

}

现在，阅读：

void readChannel(){
    //read the next channel
    HAL_ADC_Start(&hadc2);
    uint8_t ret = HAL_ADC_PollForConversion(&hadc2, 1000 /*timeout*/);
    uint16_t value = HAL_ADC_GetValue(hadc);
    printf("HAL_ADC_PollForConversion status: %d, VALLLL: %d
", ret, value);
}


int main(){
    while(1){
        //Automatically read the first channel (channel 8):
        readChannel();
        HAL_Delay(100);
        
        //Automatically read the second channel (channel 9):
        readChannel();
        HAL_Delay(100);
        
    }
}

Answer 3

您是否错过了将 io 设置为模拟输入模式？某处应该是这样的（uslay 在你的 hal msp 文件中，adc_init func）。

GPIO_InitStruct.Pin = GPIO_PIN_1;
GPIO_InitStruct.Mode = GPIO_MODE_ANALOG;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

编辑 => 你错过了 ch1

analogReadResolution(ADC_RESOLUTION);
pinMode(PA1, INPUT);
//pinMode(BATTERY_SENSE_PIN2, INPUT);
pinMode(PA2, INPUT_ANALOG);

应该和PA2一样，输入是“数字模式”。