ESP32-使用ADC笔记

基于ESP-IDF4.1

#include <stdio.h>
#include <stdlib.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/gpio.h"
#include "driver/adc.h"
#if CONFIG_IDF_TARGET_ESP32
#include "esp_adc_cal.h"
#endif

#define DEFAULT_VREF    1100        //使用 adc2_vref_to_gpio() 获得更好的估计值
#define NO_OF_SAMPLES   64          //多重采样


static esp_adc_cal_characteristics_t *adc_chars;
static const adc_channel_t channel = ADC_CHANNEL_6;     //GPIO34 if ADC1, GPIO14 if ADC2

static const adc_atten_t atten = ADC_ATTEN_DB_0;
static const adc_unit_t unit = ADC_UNIT_1;


static void check_efuse(void)
{
    //检查TP是否烧入eFuse
    if (esp_adc_cal_check_efuse(ESP_ADC_CAL_VAL_EFUSE_TP) == ESP_OK) {
        printf("eFuse Two Point: Supported
");
    } else {
        printf("eFuse Two Point: NOT supported
");
    }

    //检查Vref是否烧入eFuse
    if (esp_adc_cal_check_efuse(ESP_ADC_CAL_VAL_EFUSE_VREF) == ESP_OK) {
        printf("eFuse Vref: Supported
");
    } else {
        printf("eFuse Vref: NOT supported
");
    }
}

static void print_char_val_type(esp_adc_cal_value_t val_type)
{
    if (val_type == ESP_ADC_CAL_VAL_EFUSE_TP) {
        printf("Characterized using Two Point Value
");
    } else if (val_type == ESP_ADC_CAL_VAL_EFUSE_VREF) {
        printf("Characterized using eFuse Vref
");
    } else {
        printf("Characterized using Default Vref
");
    }
}


void app_main(void)
{

    //检查TP和Vreff是否烧录进eFuse
    check_efuse();

    //配置 ADC
    if (unit == ADC_UNIT_1) {
        adc1_config_width(ADC_WIDTH_BIT_12);
        adc1_config_channel_atten(channel, atten);
    } else {
        adc2_config_channel_atten((adc2_channel_t)channel, atten);
    }

    //描述 ADC
    adc_chars = calloc(1, sizeof(esp_adc_cal_characteristics_t));
    esp_adc_cal_value_t val_type = esp_adc_cal_characterize(unit, atten, ADC_WIDTH_BIT_12, DEFAULT_VREF, adc_chars);
    print_char_val_type(val_type);

    //连续采样ADC1
    while (1) {
        uint32_t adc_reading = 0;
        //多重采样
        for (int i = 0; i < NO_OF_SAMPLES; i++) {
            if (unit == ADC_UNIT_1) {
                adc_reading += adc1_get_raw((adc1_channel_t)channel);
            } else {
                int raw;
                adc2_get_raw((adc2_channel_t)channel, ADC_WIDTH_BIT_12, &raw);
                adc_reading += raw;
            }
        }
        adc_reading /= NO_OF_SAMPLES;

        //将ADC读取转换为毫伏的电压
        uint32_t voltage = esp_adc_cal_raw_to_voltage(adc_reading, adc_chars);
        printf("Raw: %d	Voltage: %dmV
", adc_reading, voltage);

        vTaskDelay(pdMS_TO_TICKS(1000));
    }
}

原文：https://gitee.com/EspressifSystems/esp-idf/tree/master/examples/peripherals/adc