The code is as follows：
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/*
* 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_ADC_UNIT ADC_UNIT_1
#define _EXAMPLE_ADC_UNIT_STR(unit) #unit
#define EXAMPLE_ADC_UNIT_STR(unit) _EXAMPLE_ADC_UNIT_STR(unit)
#define EXAMPLE_ADC_CONV_MODE ADC_CONV_SINGLE_UNIT_1
#define EXAMPLE_ADC_ATTEN ADC_ATTEN_DB_0
#define EXAMPLE_ADC_BIT_WIDTH SOC_ADC_DIGI_MAX_BITWIDTH
#if CONFIG_IDF_TARGET_ESP32 || CONFIG_IDF_TARGET_ESP32S2
#define EXAMPLE_ADC_OUTPUT_TYPE ADC_DIGI_OUTPUT_FORMAT_TYPE1
#define EXAMPLE_ADC_GET_CHANNEL(p_data) ((p_data)->type1.channel)
#define EXAMPLE_ADC_GET_DATA(p_data) ((p_data)->type1.data)
#else
#define EXAMPLE_ADC_OUTPUT_TYPE ADC_DIGI_OUTPUT_FORMAT_TYPE2
#define EXAMPLE_ADC_GET_CHANNEL(p_data) ((p_data)->type2.channel)
#define EXAMPLE_ADC_GET_DATA(p_data) ((p_data)->type2.data)
#endif
#define EXAMPLE_READ_LEN 256
#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_8,ADC_CHANNEL_9,};
#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++)
{
adc_pattern[i].atten = EXAMPLE_ADC_ATTEN;
adc_pattern[i].channel = channel[i] & 0x7;
adc_pattern[i].unit = EXAMPLE_ADC_UNIT;
adc_pattern[i].bit_width = EXAMPLE_ADC_BIT_WIDTH;
ESP_LOGI(TAG, "adc_pattern[%d].atten is :%" PRIx8, i, adc_pattern[i].atten);
ESP_LOGI(TAG, "adc_pattern[%d].channel is :%" PRIx8, i, adc_pattern[i].channel);
ESP_LOGI(TAG, "adc_pattern[%d].unit is :%" PRIx8, i, adc_pattern[i].unit);
}
dig_cfg.adc_pattern = adc_pattern;
ESP_ERROR_CHECK(adc_continuous_config(handle, &dig_cfg));
*out_handle = handle;
}
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);
char unit[] = EXAMPLE_ADC_UNIT_STR(EXAMPLE_ADC_UNIT);
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 = (adc_digi_output_data_t *)&result[i];
uint32_t chan_num = EXAMPLE_ADC_GET_CHANNEL(p);
uint32_t data = EXAMPLE_ADC_GET_DATA(p);
/* Check the channel number validation, the data is invalid if the channel num exceed the maximum channel */
if (chan_num < SOC_ADC_CHANNEL_NUM(EXAMPLE_ADC_UNIT))
{
ESP_LOGI(TAG, "Unit: %s, Channel: %" PRIu32 ", Value: %" PRIx32, unit, chan_num, data);
}
else
{
ESP_LOGW(TAG, "Invalid data [%s_%" PRIu32 "_%" PRIx32 "]", unit, chan_num, 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));
}
I (3949) TASK: ret is 0, ret_num is 256 bytes
I (3949) EXAMPLE: Unit: ADC_UNIT_1, Channel: 0, Value: fff
I (3949) EXAMPLE: Unit: ADC_UNIT_1, Channel: 1, Value: fff
I (3959) EXAMPLE: Unit: ADC_UNIT_1, Channel: 0, Value: fff
I (3969) EXAMPLE: Unit: ADC_UNIT_1, Channel: 1, Value: fff
I (3969) EXAMPLE: Unit: ADC_UNIT_1, Channel: 0, Value: adf
I (3979) EXAMPLE: Unit: ADC_UNIT_1, Channel: 1, Value: fff
I (3979) EXAMPLE: Unit: ADC_UNIT_1, Channel: 0, Value: fff
I (3989) EXAMPLE: Unit: ADC_UNIT_1, Channel: 1, Value: fff
I (3999) EXAMPLE: Unit: ADC_UNIT_1, Channel: 0, Value: fff
I (3999) EXAMPLE: Unit: ADC_UNIT_1, Channel: 1, Value: fff