STM32 Microcontroller ADC Sampling Practical Guide: Elaborating on Sampling Principles, Configuration, and Application for Accurate Data Acquisition

# STM32 Microcontroller ADC Sampling Practical Guide: Detailed Analysis of Sampling Principles, Configuration, and Applications for Precision Data Acquisition

## 1. ADC Sampling Principles and Configuration

### 1.1 Basic Concepts and Working Principles of ADC

An Analog-to-Digital Converter (ADC) is an electronic device that converts analog signals (such as voltage, current) into digital signals. The principle of ADC operation involves comparing the input analog signal with an internal reference voltage and then outputting a digital value that is proportional to the analog signal.

### 1.2 STM32 ADC Architecture and Configuration

STM32 microcontrollers integrate high-performance ADC modules characterized by multi-channel, high-resolution, and fast sampling rate capabilities. The configuration of the ADC module mainly includes:
- Channel Selection: Choosing the analog signal input channel to be sampled.
- Resolution: Setting the ADC sampling resolution, such as 12-bit or 16-bit.
- Sampling Rate: Setting the ADC sampling frequency, measured in samples per second (SPS).

## 2. ADC Sampling Practice

### 2.1 Initialization and Configuration of ADC Sampling

The first step in ADC sampling practice is initializing and configuring the ADC peripheral. The following steps describe how to use the STM32CubeMX tool for ADC initialization and configuration:

1. **Open the STM32CubeMX tool and select the target microcontroller.**
2. **In the "Clock Configuration" tab, configure the ADC clock source and prescaler.**
3. **In the "ADC Configuration" tab, select the ADC peripheral and channel to be used.**
4. **Configure the ADC sampling parameters, including resolution, sampling time, and trigger source.**
5. **Generate code and import it into your project.**

### 2.2 Acquisition of ADC Sampling Data

The process of acquiring ADC sampling data involves the following steps:

1. **Start ADC sampling.**
2. **Wait for the sampling to complete.**
3. **Read the ADC sampling data register.**

The following code snippet demonstrates how to use the HAL library to obtain ADC sampling data:

HAL_ADC_Start(&hadc);
HAL_ADC_PollForConversion(&hadc, 1000);
uint32_t adcValue = HAL_ADC_GetValue(&hadc);

**Parameter Explanation:**

* `hadc`: ADC handle
* `1000`: Timeout for sampling completion (milliseconds)

**Code Logic Analysis:**

1. The `HAL_ADC_Start()` function initiates ADC sampling.
2. The `HAL_ADC_PollForConversion()` function waits for sampling to finish.
3. The `HAL_ADC_GetValue()` function reads the ADC sampling data register.

### 2.3 Processing of ADC Sampling Data

ADC sampling data generally requires processing to be converted into meaningful information. Data processing steps may include:

***Calibration:** Compensate for ADC nonlinearity and other errors.
***Filtering:** Eliminate noise and interference.
***Conversion:** Convert ADC codes into actual values (e.g., voltage, temperature).

The following code snippet demonstrates how to use the HAL library to calibrate and convert ADC sampling data:

// Calibrate the ADC
HAL_ADCEx_Calibration_Start(&hadc);

// Convert ADC codes to voltage values
float voltage = HAL_ADC_GetValue(&hadc) * 3.3 / 4095.0;

**Parameter Explanation:**

* `hadc`: ADC handle
* `3.3`: ADC reference voltage (volts)
* `4095`: ADC resolution (12-bit)

**Code Logic Analysis:**

1. The `HAL_ADCEx_Calibration_Start()` function starts ADC calibration.
2. The `HAL_ADC_GetValue()` function reads the ADC sampling data register.
3. The formula to convert ADC codes into voltage values is: `Voltage = ADC Code * Reference Voltage / Resolution`.

## 3. ADC Sampling Applications

### 3.1 Voltage Sampling and Measurement

Voltage sampling is one of the most common applications of ADC. With ADC sampling, we can measure external analog voltage signals and convert them into digital signals for processing.

**Steps:**

1. **Configure the ADC channel:** Select the analog input channel to be sampled and configure ADC resolution, sampling rate, etc.
2. **Initialize the ADC:** Enable the ADC and start sampling.
3. **Obtain sampling data:** Read the sampling results from the ADC registers.
4. **Calculate the voltage value:** Calculate the sampled voltage value based on the ADC resolution and reference voltage.

**Code Example:**

#include "stm32f1xx_hal.h"

ADC_HandleTypeDef hadc;

int main() {
   // Configure the ADC channel
   hadc.Instance = ADC1;
   hadc.Init.Resolution = ADC_RESOLUTION_12B;
   hadc.Init.ScanConvMode = ADC_SCAN_DISABLE;
   hadc.Init.ContinuousConvMode = DISABLE;
   hadc.Init.DataAlign = ADC_DATAALIGN_RIGHT;
   HAL_ADC_Init(&hadc);

   // Initialize the ADC
   HAL_ADC_Start(&hadc);

   // Obtain sampling data
   uint32_t adc_data;
   HAL_ADC_PollForConversion(&hadc, HAL_MAX_DELAY);
   adc_data = HAL_ADC_GetValue(&hadc);

   // Calculate voltage value
   float voltage = adc_data * 3.3 / 4095;

   // Output voltage value
   printf("Voltage value: %.2f V\n", voltage);

   return 0;
}

**Logic Analysis:**

* Initialize the ADC with configurations for resolution, sampling rate, and data alignment.
* Start ADC sampling.
* Poll for sampling completion.
* Retrieve the ADC sampling results.
* Calculate the voltage value based on ADC resolution and reference voltage.

### 3.2 Temperature Sampling and Measurement

STM32 microcontrollers have built-in temperature sensors, which can be sampled through ADC to measure temperature.

**Steps:**

1. **Configure the ADC channel:** Select the analog input channel corresponding to the temperature sensor.
2. **Initialize the ADC:** Enable the ADC and start samplin