Add Arduino as Component examples (espressif#8878)

* Example for IDF component registry

* Added readme

* updated readme

* remove idf dependency

* add empty lines on file end

* idf_component.yml version change

* Updated readme for local development

---------

Co-authored-by: Rodrigo Garcia <[email protected]>

Author: P-R-O-C-H-Y

idf_component.yml

@@ -65,4 +65,6 @@ dependencies:
     version: "^1.4.2"
     rules:
       - if: "target in [esp32s3]"
+examples:
+  - path: ../idf_component_examples/
 

idf_component_examples/Hello_world/CMakeLists.txt

@@ -0,0 +1,8 @@
+# For more information about build system see
+# https://docs.espressif.com/projects/esp-idf/en/latest/api-guides/build-system.html
+# The following five lines of boilerplate have to be in your project's
+# CMakeLists in this exact order for cmake to work correctly
+cmake_minimum_required(VERSION 3.16)
+
+include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+project(main)

idf_component_examples/Hello_world/README.md

@@ -0,0 +1,63 @@
+| Supported Targets | ESP32 | ESP32-C2 | ESP32-C3 | ESP32-C6 | ESP32-H2 | ESP32-S2 | ESP32-S3 |
+| ----------------- | ----- | -------- | -------- | -------- | -------- | -------- | -------- |
+
+# _Hello world example_
+
+This is the simplest buildable example made to be used as a template for new projects running Arduino-esp32 as an ESP-IDF component.
+See [Arduino-esp32](https://components.espressif.com/components/espressif/arduino-esp32) in ESP Registry.
+
+## How to use example
+
+To create a ESP-IDF project from this example with the latest relase of Arduino-esp32, you can simply run command: `idf.py create-project-from-example "espressif/arduino-esp32:hello_world"`.
+ESP-IDF will download all dependencies needed from the component registry and setup the project for you.
+
+If you want to use cloned Arduino-esp32 repository, you can build this example directly.
+Go to the example folder `arduino-esp32/idf_component_examples/Hello_world`.
+First you need to comment line 6 `pre_release: true` in examples `/main/idf_component.yml`.
+Then just run command: `idf.py build`.
+
+## Example folder contents
+
+The project **Hello_world** contains one source file in C++ language [main.cpp](main/main.cpp). The file is located in folder [main](main).
+
+ESP-IDF projects are built using CMake. The project build configuration is contained in `CMakeLists.txt`
+files that provide set of directives and instructions describing the project's source files and targets
+(executable, library, or both). 
+
+Below is short explanation of remaining files in the project folder.
+
+```
+├── CMakeLists.txt
+├── main
+│   ├── CMakeLists.txt
+│   ├── idf_component.yml
+│   └── main.cpp
+└── README.md                  This is the file you are currently reading
+```
+
+## How to add Arduino libraries
+
+In the project create folder `components/` and clone the library there.
+In the library folder create new CMakeLists.txt file, add lines shown below to the file and edit the SRCS to match the library source files.
+
+```
+idf_component_register(SRCS "user_library.cpp" "another_source.c"
+                      INCLUDE_DIRS "."
+                      REQUIRES arduino-esp32
+                      )
+```
+
+Below is structure of the project folder with the Arduino libraries.
+
+```
+├── CMakeLists.txt
+├── components
+│   ├── user_library
+│   │   ├── CMakeLists.txt     This needs to be added
+│   │   ├── ...
+├── main
+│   ├── CMakeLists.txt
+│   ├── idf_component.yml
+│   └── main.cpp
+└── README.md                  This is the file you are currently reading
+```

idf_component_examples/Hello_world/main/CMakeLists.txt

@@ -0,0 +1,2 @@
+idf_component_register(SRCS "main.cpp"
+                    INCLUDE_DIRS ".")

idf_component_examples/Hello_world/main/idf_component.yml

@@ -0,0 +1,6 @@
+## IDF Component Manager Manifest File
+dependencies:
+  espressif/arduino-esp32:
+    version: '*'
+    override_path: '../../../'
+    pre_release: true

idf_component_examples/Hello_world/main/main.cpp

@@ -0,0 +1,10 @@
+#include "Arduino.h"
+
+void setup(){
+  Serial.begin(115200);
+}
+
+void loop(){
+    Serial.println("Hello world!");
+    delay(1000);
+}

idf_component_examples/Hello_world/sdkconfig.defaults

@@ -0,0 +1,12 @@
+#
+# Arduino ESP32
+#
+CONFIG_AUTOSTART_ARDUINO=y
+# end of Arduino ESP32
+
+#
+# FREERTOS
+#
+CONFIG_FREERTOS_HZ=1000
+# end of FREERTOS
+# end of Component config