ADC：采集模拟电压并进行校准

 1#include "voltage.h"
 2#include "esp_log.h"
 3#include "freertos/FreeRTOS.h"
 4#include "freertos/task.h"
 5void app_main(void)
 6{
 7    ESP_ERROR_CHECK(voltage_init());
 8    while(1) {
 9        int raw,mv; bool calibrated;
10        esp_err_t err=voltage_read(&raw,&mv,&calibrated);
11        if(err!=ESP_OK) ESP_LOGW("adc","%s",esp_err_to_name(err));
12        else if(calibrated) ESP_LOGI("adc","raw=%d voltage=%d mV",raw,mv);
13        else ESP_LOGI("adc","raw=%d (uncalibrated)",raw);
14        vTaskDelay(pdMS_TO_TICKS(200));
15    }
16}

 1#include "voltage.h"
 2#include "sdkconfig.h"
 3#include "esp_adc/adc_oneshot.h"
 4#include "esp_adc/adc_cali.h"
 5#include "esp_adc/adc_cali_scheme.h"
 6#include "esp_check.h"
 7#include "freertos/FreeRTOS.h"
 8#include "freertos/task.h"
 9static adc_oneshot_unit_handle_t s_unit;
10static adc_cali_handle_t s_calibration;
11esp_err_t voltage_init(void)
12{
13    adc_oneshot_unit_init_cfg_t u={.unit_id=ADC_UNIT_1};
14    ESP_RETURN_ON_ERROR(adc_oneshot_new_unit(&u,&s_unit),"adc","unit");
15    adc_oneshot_chan_cfg_t channel={.atten=ADC_ATTEN_DB_12,.bitwidth=ADC_BITWIDTH_DEFAULT};
16    ESP_RETURN_ON_ERROR(adc_oneshot_config_channel(s_unit,CONFIG_LESSON_ADC_CHANNEL,&channel),"adc","channel");
17    adc_cali_curve_fitting_config_t c={.unit_id=ADC_UNIT_1,.chan=CONFIG_LESSON_ADC_CHANNEL,
18        .atten=ADC_ATTEN_DB_12,.bitwidth=ADC_BITWIDTH_DEFAULT};
19    esp_err_t result=adc_cali_create_scheme_curve_fitting(&c,&s_calibration);
20    if(result!=ESP_OK) ESP_LOGW("adc","Calibration unavailable: %s; raw only",esp_err_to_name(result));
21    return ESP_OK; // 校准不可用时仍允许读取 raw。
22}
23esp_err_t voltage_read(int *raw,int *millivolts,bool *calibrated)
24{
25    int sum=0;
26    for(int i=0;i<16;i++) {
27        int value;
28        ESP_RETURN_ON_ERROR(adc_oneshot_read(s_unit,CONFIG_LESSON_ADC_CHANNEL,&value),"adc","read");
29        sum+=value;
30        vTaskDelay(pdMS_TO_TICKS(1)); // 分散采样并让出 CPU。
31    }
32    int average=sum/16,mv=0;
33    bool valid=s_calibration && adc_cali_raw_to_voltage(s_calibration,average,&mv)==ESP_OK;
34    *raw=average; *millivolts=mv; *calibrated=valid;
35    return ESP_OK;
36}

1# 应用依赖 BSP，不直接操作 ADC 句柄。
2idf_component_register(SRCS "main.c" INCLUDE_DIRS "." PRIV_REQUIRES BSP)

 1# 激活 EIM 安装的 IDF；每个新终端都需要激活。
 2source ~/.espressif/tools/activate_idf_v5.5.5.sh
 3# 进入单个示例根目录，不是在 examples 总目录运行。
 4cd ~/mycode/esp32-blog/examples/19-adc-calibration
 5# 首次配置目标；已有正确配置时不用每次重复 set-target。
 6idf.py set-target esp32s3
 7# 编译会生成 build/compile_commands.json，供 VS Code 使用。
 8idf.py build
 9# 把这个值换成实际连接开发板的端口；macOS 通常为 /dev/cu.*。
10PORT=/dev/ttyUSB0
11idf.py -p "$PORT" flash monitor
12# 串口监视退出：Ctrl+]。

1adc: raw=<采样平均值> voltage=<校准结果> mV