Merge branch 'feature/adc_demo' into 'master'

feat(adc): add add adc1 channl4(GPIO32) for adc example

add adc example

See merge request !572

examples/peripherals/adc/Makefile

@@ -0,0 +1,9 @@
+#
+# This is a project Makefile. It is assumed the directory this Makefile resides in is a
+# project subdirectory.
+#
+
+PROJECT_NAME := adc
+
+include $(IDF_PATH)/make/project.mk
+

examples/peripherals/adc/README.md

@@ -0,0 +1,17 @@
+# Example: ADC1
+
+This test code shows how to configure ADC1 and how to use ADC1 get the voltage.
+
+ 
+####ADC1 functions:
+
+ * ADC1,CHANNEL_4:GPIO32, voltage range [0v,3.1v],the Data range [0,4095]
+
+ 
+####Test:
+ * Please connect the test voltage to GPIO32
+
+ 
+
+
+

examples/peripherals/adc/main/adc1_test.c

@@ -0,0 +1,35 @@
+/* ADC1 Example
+
+   This example code is in the Public Domain (or CC0 licensed, at your option.)
+
+   Unless required by applicable law or agreed to in writing, this
+   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+   CONDITIONS OF ANY KIND, either express or implied.
+*/
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "freertos/queue.h"
+#include "driver/gpio.h"
+#include "driver/adc.h"
+
+#define ADC1_TEST_CHANNEL (4)
+
+void adc1task(void* arg)
+{
+    // initialize ADC
+    adc1_config_width(ADC_WIDTH_12Bit);
+    adc1_config_channel_atten(ADC1_TEST_CHANNEL,ADC_ATTEN_11db);
+    while(1){
+        printf("The adc1 value:%d\n",adc1_get_voltage(ADC1_TEST_CHANNEL));
+        vTaskDelay(1000/portTICK_PERIOD_MS);
+    }
+}
+
+void app_main()
+{
+    xTaskCreate(adc1task, "adc1task", 1024*3, NULL, 10, NULL);
+}
+

examples/peripherals/adc/main/component.mk

@@ -0,0 +1,3 @@
+#
+# Main Makefile. This is basically the same as a component makefile.
+#