Warning about deprecated define from ESP-IDF driver/adc.h

Question

Putting the finishing touches on an assignment (ESP-IDF PlatformIO) and my ADC initialization is throwing a warning that a define I'm calling is deprecated. It builds, so this is more in the "it bugs me" category: IOW it's not game-breaking but I'd still like to know how to fix it.

// main function
void app_main() {
    esp_event_loop_create_default();
    connect_wifi_params_t cbs = {
        .on_connected = handle_wifi_connect,
        .on_failed = handle_wifi_failed
    };

    // configure ADC for 12-bit width, 3.3V source
    // Photoresistor needs to be connected from 3.3V to pin 34.
    adc1_config_width(ADC_WIDTH_BIT_12);
    adc1_config_channel_atten(adc_channel, ADC_ATTEN_DB_11);
    
    // connect wifi
    appwifi_connect(cbs);
}

And the call to the ADC if it helps any.

// transmit reading to server. Photoresistor is read here.
static void publish_reading(int temp, int hum) {
    char buffer[5];
    if (client != NULL && enabled) {
        esp_mqtt_client_publish(client, TEMP_TOPIC, itoa(temp, buffer, 10), 0, 1, 0);
        esp_mqtt_client_publish(client, HUM_TOPIC, itoa(hum, buffer, 10), 0, 1, 0);
        // average ADC value over 32 samples and send it
        int adc_val = 0;
        for (unsigned char i = 0; i < SAMPLE_CNT; i++) adc_val += adc1_get_raw(adc_channel);
        adc_val /= SAMPLE_CNT;
        esp_mqtt_client_publish(client, PHOTO_TOPIC, itoa(adc_val, buffer, 10), 0, 1, 0);
    }
}

The warning says that ADC_ATTEN_DB_11 is deprecated.

ETA: I should clarify my troubleshooting steps: I already tried ADC_ATTEN_DB_12. The warning says "legacy adc driver is deprecated, please migrate to use esp_adc/adc_oneshot.h and esp_adc/adc_continuous.h for oneshot mode and continuous mode drivers respectively".

Answer 1

After a lot of digging, I figured out how to fix it with the purportedly new-and-improved header file. Updated code:

#include "esp_adc/adc_oneshot.h"

// define
#define SAMPLE_CNT 32 // average this number of ADC samples to get reading

// global
adc_oneshot_unit_handle_t adc1_handle;


// returns the average of 32 ADC samples
static int AverageADCSamp() {
    int samples = 0;

    for (unsigned char i = 0; i < SAMPLE_CNT; i++) {
        int rawValue = 0;
        ESP_ERROR_CHECK(adc_oneshot_read(adc1_handle, ADC_CHANNEL_6, &rawValue));
        samples += rawValue;
    }
    return samples / SAMPLE_CNT; // return the average 
}

// transmit reading to server. Photoresistor is read here.
static void publish_reading(int temp, int hum) {
    char buffer[5];
    if (client != NULL && enabled) {
        esp_mqtt_client_publish(client, TEMP_TOPIC, itoa(temp, buffer, 10), 0, 1, 0);
        esp_mqtt_client_publish(client, HUM_TOPIC, itoa(hum, buffer, 10), 0, 1, 0);
        // average ADC value over 32 samples and send it
        esp_mqtt_client_publish(client, PHOTO_TOPIC, itoa(AverageADCSamp(), buffer, 10), 0, 1, 0);
    }
}

// main function
void app_main() {
    esp_event_loop_create_default();
    connect_wifi_params_t cbs = {
        .on_connected = handle_wifi_connect,
        .on_failed = handle_wifi_failed
    };

    // configure ADC for 12-bit width, 3.3V source
    // Photoresistor needs to be connected from 3.3V to pin 34.
    adc_oneshot_unit_init_cfg_t ADC1_C6_config = {
        .unit_id = ADC_UNIT_1
    };
    ESP_ERROR_CHECK(adc_oneshot_new_unit(&ADC1_C6_config, &adc1_handle));
    adc_oneshot_chan_cfg_t channel_config = {
        .bitwidth = ADC_BITWIDTH_12,
        .atten = ADC_ATTEN_DB_12
    };
    ESP_ERROR_CHECK(adc_oneshot_config_channel(adc1_handle, ADC_CHANNEL_6, &channel_config));
    
    // connect wifi
    appwifi_connect(cbs);
}