adc: update adc_dma example README.md

examples/peripherals/adc/adc_dma/README.md

@@ -0,0 +1,63 @@
+| 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/adc_dma/main/adc_dma_example_main.c

@@ -57,7 +57,7 @@ static bool check_valid_data(const adc_digi_output_data_t *data)
     return true;
 }
 
-static void continuous_read_demo(void *arg)
+static void continuous_read(void *arg)
 {
     esp_err_t ret;
     uint32_t ret_num = 0;
@@ -90,7 +90,7 @@ static void continuous_read_demo(void *arg)
     assert(ret == ESP_OK);
 }
 
-static void single_read_demo(void *arg)
+static void single_read(void *arg)
 {
     esp_err_t ret;
     int adc1_reading[3] = {0xcc};
@@ -123,6 +123,6 @@ static void single_read_demo(void *arg)
 
 void app_main()
 {
-    single_read_demo(NULL);
+    single_read(NULL);
-    continuous_read_demo(NULL);
+    continuous_read(NULL);
 }