esp-idf/examples/peripherals/adc/continuous_read/main/continuous_read_main.c

/*
 * SPDX-FileCopyrightText: 2021-2022 Espressif Systems (Shanghai) CO LTD
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <string.h>
#include <stdio.h>
#include "sdkconfig.h"
#include "esp_log.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/semphr.h"
#include "esp_adc/adc_continuous.h"

#define EXAMPLE_READ_LEN   256
#define EXAMPLE_ADC_CONV_MODE           ADC_CONV_SINGLE_UNIT_1

#if CONFIG_IDF_TARGET_ESP32 || CONFIG_IDF_TARGET_ESP32S2
#define EXAMPLE_ADC_USE_OUTPUT_TYPE1    1
#define EXAMPLE_ADC_OUTPUT_TYPE         ADC_DIGI_OUTPUT_FORMAT_TYPE1
#else
#define EXAMPLE_ADC_OUTPUT_TYPE         ADC_DIGI_OUTPUT_FORMAT_TYPE2
#endif

#if CONFIG_IDF_TARGET_ESP32
static adc_channel_t channel[2] = {ADC_CHANNEL_6, ADC_CHANNEL_7};
#else
static adc_channel_t channel[2] = {ADC_CHANNEL_2, ADC_CHANNEL_3};
#endif

static TaskHandle_t s_task_handle;
static const char *TAG = "EXAMPLE";


static bool IRAM_ATTR s_conv_done_cb(adc_continuous_handle_t handle, const adc_continuous_evt_data_t *edata, void *user_data)
{
    BaseType_t mustYield = pdFALSE;
    //Notify that ADC continuous driver has done enough number of conversions
    vTaskNotifyGiveFromISR(s_task_handle, &mustYield);

    return (mustYield == pdTRUE);
}

static void continuous_adc_init(adc_channel_t *channel, uint8_t channel_num, adc_continuous_handle_t *out_handle)
{
    adc_continuous_handle_t handle = NULL;

    adc_continuous_handle_cfg_t adc_config = {
        .max_store_buf_size = 1024,
        .conv_frame_size = EXAMPLE_READ_LEN,
    };
    ESP_ERROR_CHECK(adc_continuous_new_handle(&adc_config, &handle));

    adc_continuous_config_t dig_cfg = {
        .sample_freq_hz = 20 * 1000,
        .conv_mode = EXAMPLE_ADC_CONV_MODE,
        .format = EXAMPLE_ADC_OUTPUT_TYPE,
    };

    adc_digi_pattern_config_t adc_pattern[SOC_ADC_PATT_LEN_MAX] = {0};
    dig_cfg.pattern_num = channel_num;
    for (int i = 0; i < channel_num; i++) {
        uint8_t unit = ADC_UNIT_1;
        uint8_t ch = channel[i] & 0x7;
        adc_pattern[i].atten = ADC_ATTEN_DB_0;
        adc_pattern[i].channel = ch;
        adc_pattern[i].unit = unit;
        adc_pattern[i].bit_width = SOC_ADC_DIGI_MAX_BITWIDTH;

        ESP_LOGI(TAG, "adc_pattern[%d].atten is :%x", i, adc_pattern[i].atten);
        ESP_LOGI(TAG, "adc_pattern[%d].channel is :%x", i, adc_pattern[i].channel);
        ESP_LOGI(TAG, "adc_pattern[%d].unit is :%x", i, adc_pattern[i].unit);
    }
    dig_cfg.adc_pattern = adc_pattern;
    ESP_ERROR_CHECK(adc_continuous_config(handle, &dig_cfg));

    *out_handle = handle;
}

static bool check_valid_data(const adc_digi_output_data_t *data)
{
#if EXAMPLE_ADC_USE_OUTPUT_TYPE1
    if (data->type1.channel >= SOC_ADC_CHANNEL_NUM(ADC_UNIT_1)) {
        return false;
    }
#else
    if (data->type2.channel >= SOC_ADC_CHANNEL_NUM(ADC_UNIT_1)) {
        return false;
    }
#endif

    return true;
}

void app_main(void)
{
    esp_err_t ret;
    uint32_t ret_num = 0;
    uint8_t result[EXAMPLE_READ_LEN] = {0};
    memset(result, 0xcc, EXAMPLE_READ_LEN);

    s_task_handle = xTaskGetCurrentTaskHandle();

    adc_continuous_handle_t handle = NULL;
    continuous_adc_init(channel, sizeof(channel) / sizeof(adc_channel_t), &handle);

    adc_continuous_evt_cbs_t cbs = {
        .on_conv_done = s_conv_done_cb,
    };
    ESP_ERROR_CHECK(adc_continuous_register_event_callbacks(handle, &cbs, NULL));
    ESP_ERROR_CHECK(adc_continuous_start(handle));

    while(1) {

        /**
         * This is to show you the way to use the ADC continuous mode driver event callback.
         * This `ulTaskNotifyTake` will block when the data processing in the task is fast.
         * However in this example, the data processing (print) is slow, so you barely block here.
         *
         * Without using this event callback (to notify this task), you can still just call
         * `adc_continuous_read()` here in a loop, with/without a certain block timeout.
         */
        ulTaskNotifyTake(pdTRUE, portMAX_DELAY);

        while (1) {
            ret = adc_continuous_read(handle, result, EXAMPLE_READ_LEN, &ret_num, 0);
            if (ret == ESP_OK) {
                ESP_LOGI("TASK", "ret is %x, ret_num is %"PRIu32" bytes", ret, ret_num);
                for (int i = 0; i < ret_num; i += SOC_ADC_DIGI_RESULT_BYTES) {
                    adc_digi_output_data_t *p = (void*)&result[i];
                    if (check_valid_data(p)) {
                #if EXAMPLE_ADC_USE_OUTPUT_TYPE1
                        ESP_LOGI(TAG, "Unit: %d, Channel: %d, Value: %x", 1, p->type1.channel, p->type1.data);
                #else
                        ESP_LOGI(TAG, "Unit: %d,_Channel: %d, Value: %x", 1, p->type2.channel, p->type2.data);
                #endif
                    } else {
                        ESP_LOGI(TAG, "Invalid data");
                    }
                }
                /**
                 * Because printing is slow, so every time you call `ulTaskNotifyTake`, it will immediately return.
                 * To avoid a task watchdog timeout, add a delay here. When you replace the way you process the data,
                 * usually you don't need this delay (as this task will block for a while).
                 */
                vTaskDelay(1);
            } else if (ret == ESP_ERR_TIMEOUT) {
                //We try to read `EXAMPLE_READ_LEN` until API returns timeout, which means there's no available data
                break;
            }
        }
    }

    ESP_ERROR_CHECK(adc_continuous_stop(handle));
    ESP_ERROR_CHECK(adc_continuous_deinit(handle));
}