ESP32-使用ADC笔记

基于ESP-IDF4.1

 1 #include <stdio.h>
 2 #include <stdlib.h>
 3 #include "freertos/FreeRTOS.h"
 4 #include "freertos/task.h"
 5 #include "driver/gpio.h"
 6 #include "driver/adc.h"
 7 #if CONFIG_IDF_TARGET_ESP32
 8 #include "esp_adc_cal.h"
 9 #endif
10
11 #define DEFAULT_VREF    1100        //使用 adc2_vref_to_gpio() 获得更好的估计值
12 #define NO_OF_SAMPLES   64          //多重采样
13
14
15 static esp_adc_cal_characteristics_t *adc_chars;
16 static const adc_channel_t channel = ADC_CHANNEL_6;     //GPIO34 if ADC1, GPIO14 if ADC2
17
18 static const adc_atten_t atten = ADC_ATTEN_DB_0;
19 static const adc_unit_t unit = ADC_UNIT_1;
20
21
22 static void check_efuse(void)
23 {
24     //检查TP是否烧入eFuse
25     if (esp_adc_cal_check_efuse(ESP_ADC_CAL_VAL_EFUSE_TP) == ESP_OK) {
26         printf("eFuse Two Point: Supported\n");
27     } else {
28         printf("eFuse Two Point: NOT supported\n");
29     }
30
31     //检查Vref是否烧入eFuse
32     if (esp_adc_cal_check_efuse(ESP_ADC_CAL_VAL_EFUSE_VREF) == ESP_OK) {
33         printf("eFuse Vref: Supported\n");
34     } else {
35         printf("eFuse Vref: NOT supported\n");
36     }
37 }
38
39 static void print_char_val_type(esp_adc_cal_value_t val_type)
40 {
41     if (val_type == ESP_ADC_CAL_VAL_EFUSE_TP) {
42         printf("Characterized using Two Point Value\n");
43     } else if (val_type == ESP_ADC_CAL_VAL_EFUSE_VREF) {
44         printf("Characterized using eFuse Vref\n");
45     } else {
46         printf("Characterized using Default Vref\n");
47     }
48 }
49
50
51 void app_main(void)
52 {
53
54     //检查TP和Vreff是否烧录进eFuse
55     check_efuse();
56
57     //配置 ADC
58     if (unit == ADC_UNIT_1) {
59         adc1_config_width(ADC_WIDTH_BIT_12);
60         adc1_config_channel_atten(channel, atten);
61     } else {
62         adc2_config_channel_atten((adc2_channel_t)channel, atten);
63     }
64
65     //描述 ADC
66     adc_chars = calloc(1, sizeof(esp_adc_cal_characteristics_t));
67     esp_adc_cal_value_t val_type = esp_adc_cal_characterize(unit, atten, ADC_WIDTH_BIT_12, DEFAULT_VREF, adc_chars);
68     print_char_val_type(val_type);
69
70     //连续采样ADC1
71     while (1) {
72         uint32_t adc_reading = 0;
73         //多重采样
74         for (int i = 0; i < NO_OF_SAMPLES; i++) {
75             if (unit == ADC_UNIT_1) {
76                 adc_reading += adc1_get_raw((adc1_channel_t)channel);
77             } else {
78                 int raw;
79                 adc2_get_raw((adc2_channel_t)channel, ADC_WIDTH_BIT_12, &raw);
80                 adc_reading += raw;
81             }
82         }
83         adc_reading /= NO_OF_SAMPLES;
84
85         //将ADC读取转换为毫伏的电压
86         uint32_t voltage = esp_adc_cal_raw_to_voltage(adc_reading, adc_chars);
87         printf("Raw: %d\tVoltage: %dmV\n", adc_reading, voltage);
88
89         vTaskDelay(pdMS_TO_TICKS(1000));
90     }
91 }

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