doc(esp-idf link): update esp-idf doc link

Author: Yuan Ming Fu

.gitignore

@@ -5,4 +5,38 @@ build/
 *.pyc
 *.d
 *.old
-*.cproject
+*.cproject
+
+# vscode setting
+.vscode/
+
+# eclipse setting
+.settings
+
+# MacOS directory files
+.DS_Store
+
+# Doc build artifacts
+docs/*/_build/
+docs/*/doxygen-warning-log.txt
+docs/*/sphinx-warning-log.txt
+docs/*/sphinx-warning-log-sanitized.txt
+docs/*/xml/
+docs/*/xml_in/
+docs/*/man/
+docs/doxygen_sqlite3.db
+
+# Example project files
+examples/**/sdkconfig
+examples/**/sdkconfig.old
+examples/**/build
+
+# Unit test app files
+tools/unit-test-app/sdkconfig
+tools/unit-test-app/sdkconfig.old
+tools/unit-test-app/build
+tools/unit-test-app/builds
+tools/unit-test-app/output
+
+# ESP-IDF library 
+build

CONTRIBUTING.md

@@ -16,9 +16,9 @@ Before sending us a Pull Request, please consider this list of points:
 
 * Is the contribution entirely your own work, or already licensed under an Apache License 2.0 compatible Open Source License? If not then we unfortunately cannot accept it.
 
-* Does any new code conform to the esp-idf : [Style Guide](http://docs.espressif.com/projects/esp-idf/en/latest/contribute/style-guide.html)?
+* Does any new code conform to the esp-idf : [Style Guide](http://docs.espressif.com/projects/esp-idf/en/stable/contribute/style-guide.html)?
 
-* Does the code documentation follow requirements in :doc: [documenting-code](http://docs.espressif.com/projects/esp-idf/en/latest/contribute/documenting-code.html)?
+* Does the code documentation follow requirements in :doc: [documenting-code](http://docs.espressif.com/projects/esp-idf/en/stable/contribute/documenting-code.html)?
 
 * Is the code adequately commented for people to understand how it is structured?
 
@@ -40,4 +40,4 @@ If this process passes, it will be merged onto the public github repository.
 Legal Part
 ----------
 
-Before a contribution can be accepted, you will need to sign our : [contributor-agreement](http://docs.espressif.com/projects/esp-idf/en/latest/contribute/contributor-agreement.html). You will be prompted for this automatically as part of the Pull Request process.
+Before a contribution can be accepted, you will need to sign our : [contributor-agreement](http://docs.espressif.com/projects/esp-idf/en/stable/contribute/contributor-agreement.html). You will be prompted for this automatically as part of the Pull Request process.

README.md

@@ -222,7 +222,7 @@
 
 ## <h2 id="preparation">Preparation(CMake)</h2>
 
-* Add to PATH the path to the tools directory inside the IDF_PATH directory.[Add IDF_PATH & idf.py PATH to User Profile(CMake)](https://docs.espressif.com/projects/esp-idf/en/latest/get-started-cmake/add-idf_path-to-profile.html)
+* Add to PATH the path to the tools directory inside the IDF_PATH directory.[Add IDF_PATH & idf.py PATH to User Profile(CMake)](https://docs.espressif.com/projects/esp-idf/en/stable/get-started-cmake/add-idf_path-to-profile.html)
 * To clone this repository by
 
     ```

documents/DFS_and_light_sleep/DFS_test_manual_en.md

@@ -166,4 +166,4 @@ We created a task to test DFS, and result are as follows:
 |   160MHz  |         28.46mA     |
 |   240MHz  |         39.95mA     |
 
-More informations about DFS, please Visit [Power Management](http://docs.espressif.com/projects/esp-idf/en/latest/api-reference/system/power_management.html)
+More informations about DFS, please Visit [Power Management](http://docs.espressif.com/projects/esp-idf/en/stable/api-reference/system/power_management.html)

documents/DFS_and_light_sleep/light_sleep_test_manual_cn.md

@@ -4,7 +4,7 @@
 
 - **1. 工具链的安装**
 
-esp-iot-solution 使用 esp-idf 同一套工具链, 所以如果你的平台上能够编译 esp-idf 中的 example, 则工具链无须重复安装. 工具链的详细安装步骤可以在 [ESP-IDF Programming Guide](https://docs.espressif.com/projects/esp-idf/en/latest/get-started/index.html) 找到, 这里与不多加描述.
+esp-iot-solution 使用 esp-idf 同一套工具链, 所以如果你的平台上能够编译 esp-idf 中的 example, 则工具链无须重复安装. 工具链的详细安装步骤可以在 [ESP-IDF Programming Guide](https://docs.espressif.com/projects/esp-idf/en/stable/get-started/index.html) 找到, 这里与不多加描述.
 
 - **2. 测试代码下载**
 

documents/evaluation_boards/ESP-Prog_guide_cn.md

@@ -115,7 +115,7 @@ IO0 是 ESP8266 和 ESP32 的 Boot 模式选择管脚，芯片上电后 IO0 做
 
 - [ESP-Prog PCB 文件](http://espressif.com/zh-hans/support/download/documents?keys=参考设计)
 
-- [ESP32 JTAG 调试使用介绍](https://docs.espressif.com/projects/esp-idf/en/latest/api-guides/jtag-debugging/index.html#)
+- [ESP32 JTAG 调试使用介绍](https://docs.espressif.com/projects/esp-idf/en/stable/api-guides/jtag-debugging/index.html#)
 
 - [ Flash 下载工具 (ESP8266 & ESP32)](http://www.espressif.com/zh-hans/support/download/other-tools#)
 

documents/evaluation_boards/ESP-Prog_guide_en.md

@@ -113,7 +113,7 @@ Pin IO0 can be set to select ESP8266's and ESP32's boot modes. This pin can be u
 
 - [ESP-Prog schematics, PCB reference design, BOM](http://espressif.com/en/support/download/documents?keys=Reference+Design)
 
-- [Introduction to the ESP32 JTAG Debugging](https://docs.espressif.com/projects/esp-idf/en/latest/api-guides/jtag-debugging/index.html#)
+- [Introduction to the ESP32 JTAG Debugging](https://docs.espressif.com/projects/esp-idf/en/stable/api-guides/jtag-debugging/index.html#)
 
 - [ Flash Download Tools (ESP8266 & ESP32)](http://espressif.com/en/support/download/other-tools)
 

documents/evaluation_boards/ESP32_LCDKit_guide_cn.md

@@ -46,7 +46,7 @@ DAC-Audio 模块 | 连接喇叭播放音频，包含音频功率放大器
 
 ## 3.1 ESP32 DevKitC 开发板连接模块
 
-使用 ESP32-LCDKit 开发板进行 HMI 相关开发时需要搭配使用 [ESP32 DevKitC 开发板](https://docs.espressif.com/projects/esp-idf/en/latest/hw-reference/modules-and-boards.html#esp32-devkitc-v4)。
+使用 ESP32-LCDKit 开发板进行 HMI 相关开发时需要搭配使用 [ESP32 DevKitC 开发板](https://docs.espressif.com/projects/esp-idf/en/stable/hw-reference/modules-and-boards.html#esp32-devkitc-v4)。
 
 ESP32-LCDKit 开发板与 ESP32 DevKitC 开发板连接模块电路原理图如下所示：
 

documents/evaluation_boards/ESP32_LCDKit_guide_en.md

@@ -44,7 +44,7 @@ This section introduces the functional modules (interfaces) of ESP32-LCDKit and
 
 ## 3.1 ESP32 DevKitC Connection Module
 
-For the HMI-related development with ESP32-LCDKit, you also need the [ESP32 DevKitC](https://docs.espressif.com/projects/esp-idf/en/latest/hw-reference/modules-and-boards.html#esp32-devkitc-v4) development board.
+For the HMI-related development with ESP32-LCDKit, you also need the [ESP32 DevKitC](https://docs.espressif.com/projects/esp-idf/en/stable/hw-reference/modules-and-boards.html#esp32-devkitc-v4) development board.
 
 The figure below shows the schematics for the ESP32 DevKitC connection module.
 

documents/evaluation_boards/esp32_sense_kit_guide_cn.md

@@ -11,7 +11,7 @@ ESP32-Sense 开发套件用于评估和开发 ESP32 触摸传感器功能。评
 ## 2. 相关资源
 
 - **开发环境**  
-    - [ESP-IDF](https://github.com/espressif/esp-idf) 是 ESP32 平台的软件开发包。文档 [Get Started](https://docs.espressif.com/projects/esp-idf/en/latest/get-started/index.html) 介绍编译环境的搭建和软件开发包的使用说明。
+    - [ESP-IDF](https://github.com/espressif/esp-idf) 是 ESP32 平台的软件开发包。文档 [Get Started](https://docs.espressif.com/projects/esp-idf/en/stable/get-started/index.html) 介绍编译环境的搭建和软件开发包的使用说明。
     - [ESP-Prog](./ESP-Prog_guide_cn.md) 是 ESP32 调试工具，有下载和 Jtag 调试功能。
 
 - **ESP32 IoT 应用方案**  
@@ -24,7 +24,7 @@ ESP32-Sense 开发套件用于评估和开发 ESP32 触摸传感器功能。评
 
 - **其他参考资料**  
     - [Espressif 官网](http://www.espressif.com)
-    - [ESP32 编程指南](https://docs.espressif.com/projects/esp-idf/en/latest/index.html) : ESP32 相关开发文档的汇总平台，包含硬件手册，软件 API 介绍等。
+    - [ESP32 编程指南](https://docs.espressif.com/projects/esp-idf/en/stable/index.html) : ESP32 相关开发文档的汇总平台，包含硬件手册，软件 API 介绍等。
     - [触摸传感器应用设计参考文档](../touch_pad_solution/readme_cn.md): ESP32 触摸传感器功能应用设计手册，包括触摸传感器原理介绍，软件设计，PCB 设计等内容。
 
 - **技术支持**  

documents/evaluation_boards/esp32_sense_kit_guide_en.md

@@ -14,7 +14,7 @@ The following image shows the whole ESP32-Sense development kit.
 ## 2. Related Resources
 
 - **Set up Software Environment**  
-    - [ESP-IDF](https://github.com/espressif/esp-idf) is the SDK for ESP32. You can refer to [Get Started](https://docs.espressif.com/projects/esp-idf/en/latest/get-started/index.html) for how to set up the ESP32 software environment.
+    - [ESP-IDF](https://github.com/espressif/esp-idf) is the SDK for ESP32. You can refer to [Get Started](https://docs.espressif.com/projects/esp-idf/en/stable/get-started/index.html) for how to set up the ESP32 software environment.
     - [ESP-Prog](./ESP-Prog_guide_en.md) is the debugger for ESP32 that features download and debugging functions.
 
 - **ESP32 IoT Solution**  
@@ -27,7 +27,7 @@ The following image shows the whole ESP32-Sense development kit.
 
 - **Related Resources**  
     - [Espressif website](https://espressif.com)
-    - [ESP32 programming guide](https://docs.espressif.com/projects/esp-idf/en/latest/index.html): It hosts extensive documentation for ESP-IDF ranging from hardware guides to API reference.   
+    - [ESP32 programming guide](https://docs.espressif.com/projects/esp-idf/en/stable/index.html): It hosts extensive documentation for ESP-IDF ranging from hardware guides to API reference.   
     - [ESP32 touch sensor design](../touch_pad_solution/readme_en.md): It is the reference design manual for the ESP32 touch sensor system.
 
 - **Technical Support**  

documents/hmi_solution/hmi_workflow_cn.md

@@ -206,7 +206,7 @@
 
 4. ESP32 平台选择
 
-    在 mp3_example 中使用 LittlevGL GUI 库进行开发，对内存资源要求低，所以选择 [ESP32 DevKitC](https://docs.espressif.com/projects/esp-idf/en/latest/hw-reference/modules-and-boards.html#esp32-devkitc-v4) 开发板搭配 [ESP-WROOM32](https://docs.espressif.com/projects/esp-idf/en/latest/hw-reference/modules-and-boards.html#esp32-wroom-32) 模组进行开发
+    在 mp3_example 中使用 LittlevGL GUI 库进行开发，对内存资源要求低，所以选择 [ESP32 DevKitC](https://docs.espressif.com/projects/esp-idf/en/stable/hw-reference/modules-and-boards.html#esp32-devkitc-v4) 开发板搭配 [ESP-WROOM32](https://docs.espressif.com/projects/esp-idf/en/stable/hw-reference/modules-and-boards.html#esp32-wroom-32) 模组进行开发
 
 5. 基于 [ESP32 LittlevGL](https://github.com/espressif/esp-iot-solution/tree/master/components/hmi/lvgl_gui) 库进行移植、相关驱动开发
 

documents/hmi_solution/hmi_workflow_en.md

@@ -199,7 +199,7 @@ This section uses an [mp3_example](../../examples/hmi/mp3_example/README_en.md)
 
 4. Select the project-specific ESP32 module.
 
-   As the LittlevGL GUI library requires minimum memory, you can select the [ESP-WROOM32](https://docs.espressif.com/projects/esp-idf/en/latest/hw-reference/modules-and-boards.html#esp32-wroom-32) module and mount it on the [ESP32 DevKitC](https://docs.espressif.com/projects/esp-idf/en/latest/hw-reference/modules-and-boards.html#esp32-devkitc-v4) development board.
+   As the LittlevGL GUI library requires minimum memory, you can select the [ESP-WROOM32](https://docs.espressif.com/projects/esp-idf/en/stable/hw-reference/modules-and-boards.html#esp32-wroom-32) module and mount it on the [ESP32 DevKitC](https://docs.espressif.com/projects/esp-idf/en/stable/hw-reference/modules-and-boards.html#esp32-devkitc-v4) development board.
 
 5. Port the [ESP32 LittlevGL](https://github.com/espressif/esp-iot-solution/tree/master/components/hmi/lvgl_gui) library to your project, or port your project-related resources to [esp-iot-solution](https://github.com/espressif/esp-iot-solution) if you choose to use it, and develop related drivers.
 

documents/low_power_solution/esp32_ulp_co-processor_and_assembly_environment_setup_cn.md

@@ -33,15 +33,15 @@ ULP 协处理器的主要特性有：
 ## 3. 配置 ULP 协处理器编译环境
 ULP 协处理器目前只支持汇编开发，我们提供了三种不同平台（Linux，Windows，MacOS）的 ULP 协处理器编译环境的设置方法。
 
-需说明：在安装汇编工具链之前，我们默认你已经安装和配置好 ESP32 ESP-IDF C 语言编译工具链，[安装参考链接](https://docs.espressif.com/projects/esp-idf/en/latest/get-started/index.html#setup-toolchain)。
+需说明：在安装汇编工具链之前，我们默认你已经安装和配置好 ESP32 ESP-IDF C 语言编译工具链，[安装参考链接](https://docs.espressif.com/projects/esp-idf/en/stable/get-started/index.html#setup-toolchain)。
 
 #### 3.1 Linux
 Linux 下配置编译环境比较简单，只需要下载汇编编译工具链，解压到安装目录中，再添加环境变量即可完成设置。
 1. 下载工具链 [binutils-esp32ulp toolchain Linux(x64)]( https://github.com/espressif/binutils-esp32ulp/wiki#downloads)
 2. 解压到要安装的目录,添加工具链的 `bin` 目录到环境变量 `PATH` 中。例如，解压目录是 `/opt/esp32ulp-elf-binutils` 那么添加 `export PATH=/opt/esp32ulp-elf-binutils/bin:$PATH` 这一行到 `.bashrc` 文件中，运行 `source .bashrc` 使上述环境变量生效，这样，ULP 的汇编环境就设置完毕了。
 
 #### 3.2 Windows
-首先安装 Windows / MSYS2 下的 C 编译工具链可参考[说明链接]( http://docs.espressif.com/projects/esp-idf/en/latest/get-started/windows-setup.html) ，之后再安装 ULP 协处理器[编译工具链链接]( https://github.com/espressif/binutils-esp32ulp/wiki#downloads)
+首先安装 Windows / MSYS2 下的 C 编译工具链可参考[说明链接]( https://docs.espressif.com/projects/esp-idf/en/stable/get-started/windows-setup.html) ，之后再安装 ULP 协处理器[编译工具链链接]( https://github.com/espressif/binutils-esp32ulp/wiki#downloads)
 1. 解压 ULP 工具链 `esp32ulp-elf-binutils-win32-...` 到 MSYS2 的 `opt` 目录中，一般建议使用 `C:\msys32\opt` 目录，因为 `ESP32 toolchain xtensa-esp32-elf` 也在这个目录下。
 
 2. 打开位于目录 `C:\msys32\etc\profile.d` 下的 `esp32_toolchain.sh` 文件，把 ULP 工具链的 `bin/`目录添加到 path 中，设置例如：
@@ -62,7 +62,7 @@ MacOS 平台编译设置几乎是和 Linux 一样的，但需下载 MacOS 平台
 如果把 ULP 汇编代码编译为应用组件的一部分，必须采取以下步骤：
 
 1. ULP 的代码是汇编写的，并且文件后缀格式是.S, 这些汇编文件必须放在一个单独的目录中，例如 ulp/
-2. 修改 makefile 添加如下内容，一些详细的定义在 [Compiling ULP code](http://docs.espressif.com/projects/esp-idf/en/latest/api-guides/ulp.html#compiling-ulp-code) 可以找到解释。
+2. 修改 makefile 添加如下内容，一些详细的定义在 [Compiling ULP code](https://docs.espressif.com/projects/esp-idf/en/stable/api-guides/ulp.html#compiling-ulp-code) 可以找到解释。
 ```
 ULP_APP_NAME ?= ulp_$(COMPONENT_NAME)
 ULP_S_SOURCES = $(COMPONENT_PATH)/ulp/ulp_source_file.S
@@ -72,7 +72,7 @@ include $(IDF_PATH)/components/ulp/component_ulp_common.mk
 3. 至此，可以编译包含 ULP 协处理器汇编代码的应用程序了。
 
 ## 5. ULP 协处理器的汇编指令
-汇编指令目前有 24 条，在 [ULP coprocessor instruction set](http://docs.espressif.com/projects/esp-idf/en/latest/api-guides/ulp_instruction_set.html#add-add-to-register) 获得更详细的说明。 
+汇编指令目前有 24 条，在 [ULP coprocessor instruction set](https://docs.espressif.com/projects/esp-idf/en/stable/api-guides/ulp_instruction_set.html#add-add-to-register) 获得更详细的说明。 
 
 ##### 算数与逻辑类运算的指令
 * 算数指令：加 ADD，减 SUB
@@ -122,4 +122,4 @@ include $(IDF_PATH)/components/ulp/component_ulp_common.mk
 
 ## 7. 引用文档
 * [ESP-IOT-SOLUTION 的低功耗方案文档]( https://github.com/espressif/esp-iot-solution/tree/master/documents/low_power_solution)
-* [ULP coprocessor programming]( https://docs.espressif.com/projects/esp-idf/en/latest/api-guides/ulp.html)
+* [ULP coprocessor programming]( https://docs.espressif.com/projects/esp-idf/en/stable/api-guides/ulp.html)

documents/low_power_solution/esp32_ulp_co-processor_and_assembly_environment_setup_en.md

@@ -47,7 +47,7 @@ The ULP co-processor can only be developed in assembly and compiled using the to
 The ULP co-processor assembly enviroment is set up now.
 
 #### 3.2 Windows
-1. Install download the Windows all-in-one toolchain & MSYS2 zip file. Please refer to [standard setup of toolchain for windows](http://docs.espressif.com/projects/esp-idf/en/latest/get-started/windows-setup.html).
+1. Install download the Windows all-in-one toolchain & MSYS2 zip file. Please refer to [standard setup of toolchain for windows](https://docs.espressif.com/projects/esp-idf/en/stable/get-started/windows-setup.html).
 2. Download [ULP toolchain](https://github.com/espressif/binutils-esp32ulp/wiki#downloads).
 3. Unzlip the ULP toolchain `esp32ulp-elf-binutils-win32-...` into MSYS2's `opt` directory. `C:\msys32\opt` directory is recommended, since it also contains the ESP32 toolchain `xtensa-esp32-elf`.
 4. Open `esp32_toolchain.sh` file in `C:\msys32\etc\profile.d` directory for editing and add the path to the `bin` directory of the toolchain to the `PATH` environment variable, as shown below:  
@@ -75,13 +75,13 @@ ULP_S_SOURCES = $(COMPONENT_PATH)/ulp/ulp_source_file.S
 ULP_EXP_DEP_OBJECTS := main.o
 include $(IDF_PATH)/components/ulp/component_ulp_common.mk
 ```
-Each line is explained in [Compiling ULP Code](http://docs.espressif.com/projects/esp-idf/en/latest/api-guides/ulp.html#compiling-ulp-code).
+Each line is explained in [Compiling ULP Code](https://docs.espressif.com/projects/esp-idf/en/stable/api-guides/ulp.html#compiling-ulp-code).
 
 3. Build the application as usual (e.g. make app).
 
 ## 5. Assembly Instructions
 
-There are 24 assembly instructions for the ULP co-processor that are documented in details in [ULP coprocessor instruction set](http://docs.espressif.com/projects/esp-idf/en/latest/api-guides/ulp_instruction_set.html).
+There are 24 assembly instructions for the ULP co-processor that are documented in details in [ULP coprocessor instruction set](https://docs.espressif.com/projects/esp-idf/en/stable/api-guides/ulp_instruction_set.html).
 
 #### Algorithm and logical instructions
 * Algorithm instructions: ADD (add to register), SUB (subtract from register)
@@ -131,4 +131,4 @@ You can find some ULP co-processor examples within [esp-iot-solution](https://gi
 
 ## 7. Related Documents
 * [Low Power Solution](https://github.com/espressif/esp-iot-solution/tree/master/documents/low_power_solution)
-* [ULP Co-processor Programming](https://docs.espressif.com/projects/esp-idf/en/latest/api-guides/ulp.html)
+* [ULP Co-processor Programming](https://docs.espressif.com/projects/esp-idf/en/stable/api-guides/ulp.html)