adc: add adc programming guide on c3

examples/peripherals/adc/esp32c3/adc/CMakeLists.txt

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+# The following lines of boilerplate have to be in your project's CMakeLists
+# in this exact order for cmake to work correctly
+cmake_minimum_required(VERSION 3.5)
+
+include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+project(adc)

examples/peripherals/adc/esp32c3/adc/README.md

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+| Supported Targets | ESP32-C3 |
+| ----------------- | -------- |
+
+# ADC DMA Example
+
+(See the README.md file in the upper level 'examples' directory for more information about examples.)
+
+This example shows how to use DMA-Read-APIs and Single-Read-APIs to read voltage from GPIO pins via ADC controller.
+
+## How to use example
+
+### Hardware Required
+
+* A development board with ESP32C3 SoC
+* A USB cable for power supply and programming
+
+For `single_read` (Single-Read-APIs example), we use `ADC1_CHANNEL_2`, `ADC1_CHANNEL_3`, `ADC1_CHANNEL_4`, `ADC2_CHANNEL_0`. Hence we need to connect voltage sources (0 ~ 3.3V) to GPIO2, GPIO3, GPIO4, GPIO5 respectively.
+
+For `continuous_read` (DMA-Read-APIs example), we use `ADC1_CHANNEL_0`, `ADC1_CHANNEL_1` and `ADC2_CHANNEL_0`. Therefore, GPIO0, GPIO1 and GPIO5 should be connected to voltage sources (0 ~ 3.3V).
+
+If other ADC units/channels are selected in your application, you need to change the GPIO pin (please refer to the `ESP32C3 Technical Reference Manual`).
+
+### Configure the project
+
+```
+idf.py menuconfig
+```
+
+### Build and Flash
+
+Build the project and flash it to the board, then run monitor tool to view serial output:
+
+```
+idf.py -p PORT flash monitor
+```
+
+(To exit the serial monitor, type ``Ctrl-]``.)
+
+See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.
+
+## Example Output
+
+Running this example, you will see the following log output on the serial monitor:
+```
+I (322) ADC1_CH2: 7c8
+I (322) ADC1_CH3: 278
+I (322) ADC1_CH4: d4b
+I (322) ADC2_CH0: 48
+```
+```
+ADC1_CH0: 61b
+ADC1_CH1: 39b
+ADC2_CH0: 4b
+```
+
+## Troubleshooting
+
+* program upload failure
+
+    * Hardware connection is not correct: run `idf.py -p PORT monitor`, and reboot your board to see if there are any output logs.
+    * The baud rate for downloading is too high: lower your baud rate in the `menuconfig` menu, and try again.
+
+For any technical queries, please open an [issue](https://github.com/espressif/esp-idf/issues) on GitHub. We will get back to you soon.

examples/peripherals/adc/esp32c3/adc/main/CMakeLists.txt

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+idf_component_register(SRCS "adc_dma_example_main.c"
+                    INCLUDE_DIRS ".")

examples/peripherals/adc/esp32c3/adc/main/adc_dma_example_main.c

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+#include <string.h>
+#include <stdio.h>
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "freertos/semphr.h"
+#include "esp_log.h"
+#include "driver/adc.h"
+
+#define TIMES 256
+
+static void continuous_adc_init(uint16_t adc1_chan_mask, uint16_t adc2_chan_mask, adc_channel_t *channel, uint8_t channel_num)
+{
+    esp_err_t ret = ESP_OK;
+    assert(ret == ESP_OK);
+
+    adc_digi_init_config_t adc_dma_config = {
+        .max_store_buf_size = 1024,
+        .conv_num_each_intr = 256,
+        .adc1_chan_mask = adc1_chan_mask,
+        .adc2_chan_mask = adc2_chan_mask,
+    };
+    ret = adc_digi_initialize(&adc_dma_config);
+    assert(ret == ESP_OK);
+
+    adc_digi_pattern_table_t adc_pattern[10] = {0};
+
+    //Do not set the sampling frequency out of the range between `SOC_ADC_SAMPLE_FREQ_THRES_LOW` and `SOC_ADC_SAMPLE_FREQ_THRES_HIGH`
+    adc_digi_config_t dig_cfg = {
+        .conv_limit_en = 0,
+        .conv_limit_num = 250,
+        .sample_freq_hz = 620,
+    };
+
+    dig_cfg.adc_pattern_len = channel_num;
+    for (int i = 0; i < channel_num; i++) {
+        uint8_t unit = ((channel[i] >> 3) & 0x1);
+        uint8_t ch = channel[i] & 0x7;
+        adc_pattern[i].atten = ADC_ATTEN_DB_0;
+        adc_pattern[i].channel = ch;
+        adc_pattern[i].unit = unit;
+    }
+    dig_cfg.adc_pattern = adc_pattern;
+    ret = adc_digi_controller_config(&dig_cfg);
+    assert(ret == ESP_OK);
+}
+
+static bool check_valid_data(const adc_digi_output_data_t *data)
+{
+    const unsigned int unit = data->type2.unit;
+    if (unit > 2) return false;
+    if (data->type2.channel >= SOC_ADC_CHANNEL_NUM(unit)) return false;
+
+    return true;
+}
+
+static void continuous_read(void *arg)
+{
+    esp_err_t ret;
+    uint32_t ret_num = 0;
+    uint8_t result[TIMES] = {0};
+    memset(result, 0xcc, TIMES);
+
+    uint16_t adc1_chan_mask = BIT(0) | BIT(1);
+    uint16_t adc2_chan_mask = BIT(0);
+    adc_channel_t channel[3] = {ADC1_CHANNEL_0, ADC1_CHANNEL_1, (ADC2_CHANNEL_0 | 1 << 3)};
+
+    continuous_adc_init(adc1_chan_mask, adc2_chan_mask, channel, sizeof(channel) / sizeof(adc_channel_t));
+    adc_digi_start();
+
+    int n = 20;
+    while(n--) {
+        ret = adc_digi_read_bytes(result, TIMES, &ret_num, ADC_MAX_DELAY);
+        for (int i = 0; i < ret_num; i+=4) {
+            adc_digi_output_data_t *p = (void*)&result[i];
+            if (check_valid_data(p)) {
+                printf("ADC%d_CH%d: %x\n", p->type2.unit+1, p->type2.channel, p->type2.data);
+            } else {
+                printf("Invalid data [%d_%d_%x]\n", p->type2.unit+1, p->type2.channel, p->type2.data);
+            }
+        }
+        // If you see task WDT in this task, it means the conversion is too fast for the task to handle
+    }
+
+    adc_digi_stop();
+    ret = adc_digi_deinitialize();
+    assert(ret == ESP_OK);
+}
+
+static void single_read(void *arg)
+{
+    esp_err_t ret;
+    int adc1_reading[3] = {0xcc};
+    int adc2_reading[1] = {0xcc};
+
+    const char TAG_CH[][10] = {"ADC1_CH2", "ADC1_CH3","ADC1_CH4", "ADC2_CH0"};
+
+    adc1_config_width(ADC_WIDTH_BIT_DEFAULT);
+    adc1_config_channel_atten(ADC1_CHANNEL_2, ADC_ATTEN_DB_0);
+    adc1_config_channel_atten(ADC1_CHANNEL_3, ADC_ATTEN_DB_6);
+    adc1_config_channel_atten(ADC1_CHANNEL_4, ADC_ATTEN_DB_0);
+    adc2_config_channel_atten(ADC2_CHANNEL_0, ADC_ATTEN_DB_0);
+
+    int n = 20;
+    while (n--) {
+
+        adc1_reading[0] = adc1_get_raw(ADC1_CHANNEL_2);
+        adc1_reading[1] = adc1_get_raw(ADC1_CHANNEL_3);
+        adc1_reading[2] = adc1_get_raw(ADC1_CHANNEL_4);
+
+        for (int i = 0; i < 3; i++) {
+            ESP_LOGI(TAG_CH[i], "%x", adc1_reading[i]);
+        }
+
+        ret = adc2_get_raw(ADC2_CHANNEL_0, ADC_WIDTH_BIT_12, &adc2_reading[0]);
+        assert(ret == ESP_OK);
+        ESP_LOGI(TAG_CH[3], "%x", adc2_reading[0]);
+    }
+}
+
+void app_main(void)
+{
+    single_read(NULL);
+    continuous_read(NULL);
+}