CHIP ESP32 Pigweed Example Application

The ESP32 example demonstrates the usage of Pigweed module functionalities in an application.

The example is based on CHIP, the Pigweed module, which is a collection of libraries that provide different functionalities for embedded systems, and the ESP32 platform.

You can use this example as a training ground for making experiments, testing Pigweed module features and checking what actions are necessary to fully integrate Pigweed in a CHIP project.

Pigweed functionalities are being gradually integrated into CHIP. Currently, the following features are available:

Echo RPC - Creates a Remote Procedure Call server and allows sending commands through the serial port to the device, which makes echo and sends the received commands back.

CHIP ESP32 Pigweed Example Application
- Building the Example Application
  - To build the application, follow these steps:
- Testing the Example Application

Building the Example Application

Building the example application requires the use of the Espressif ESP32 IoT Development Framework and the xtensa-esp32-elf toolchain.

The VSCode devcontainer has these components pre-installed, so you can skip this step. To install these components manually, follow these steps:

Clone the Espressif ESP-IDF and checkout release/v4.2 branch

  $ mkdir ${HOME}/tools
  $ cd ${HOME}/tools
  $ git clone https://github.com/espressif/esp-idf.git
  $ cd esp-idf
  $ git checkout release/v4.2
  $ git submodule update --init
  $ export IDF_PATH=${HOME}/tools/esp-idf
  $ ./install.sh

Install ninja-build
```
  $ sudo apt-get install ninja-build
```

To build the application, follow these steps:

Currently building in VSCode and deploying from native is not supported, so make sure the IDF_PATH has been exported(See the manual setup steps above).

In the root of the example directory, sync the CHIP tree's submodules and source idf.sh. Note: This does not have to be repeated for incremental builds.
```
  $ source idf.sh
```

Configuration Options

To choose from the different configuration options, run menuconfig

  $ idf make menuconfig

This example uses UART0 for serial communication. You can change this through
`PW RPC Example Configuration`. As a result, the console has been shifted to UART1
You can change this through `Component config` -> `Common ESP-related` ->
`UART for console output`

To use the default configuration options, run the default config

  $ idf make defconfig

Run make to build the demo application.
```
  $ idf make
```
After building the application, to flash it outside of VSCode, connect your device via USB. Then run the following command to flash the demo application onto the device and then monitor its output. If necessary, replace /dev/tty.SLAB_USBtoUART(MacOS) with the correct USB device name for your system(like /dev/ttyUSB0 on Linux). Note that sometimes you might have to press and hold the boot button on the device while it's trying to connect before flashing. For ESP32-DevKitC devices this is labeled in the functional description diagram.
```
  $ idf make flash ESPPORT=/dev/tty.SLAB_USBtoUART
```
Note: Some users might have to install the VCP driver before the device shows up on /dev/tty.

Testing the Example Application

Run the following command to start an interactive Python shell, where the Echo RPC commands can be invoked:

    python -m pw_hdlc.rpc_console --device /dev/tty.SLAB_USBtoUART -b 115200 $CHIP_ROOT/third_party/pigweed/repo/pw_rpc/pw_rpc_protos/echo.proto -o /tmp/pw_rpc.out

To send an Echo RPC message, type the following command, where the actual message is the text in quotation marks after the msg= phrase:

    rpcs.pw.rpc.EchoService.Echo(msg="hi")