wasm-micro-runtime/samples/gui

Introduction

This sample demonstrates that a graphic user interface application in WebAssembly programming with WAMR graphic library(WGL) extension. WGL is implemented based on LittlevGL, an open-source embedded 2d graphic library. LittlevGL source code is built into the WAMR runtime and exported to Webassembly application with WGL extension. These extension API's are listed in: <wamr_root>/core/iwasm/lib/app-libs/extension/gui/wgl.h. Currently only a small set of API's are provided and that would be extended in future.

The runtime component supports building target for Linux and Zephyr/STM Nucleo board. The beauty of this sample is the WebAssembly application can have identical display and behavior when running from both runtime environments. That implies we can do majority of application validation from desktop environment as long as two runtime distributions support the same set of application interface.

The sample also provides the native Linux version of application without the runtime under folder "lvgl-native-ui-app". It can help to check differences between the implementations in native and WebAssembly.

The number on top will plus one each second, and the number on the bottom will plus one when clicked.

Install required SDK and libraries

• 32 bit SDL(simple directmedia layer) Use apt-get
sudo apt-get install libsdl2-dev:i386

Or download source from www.libsdl.org
./configure C_FLAGS=-m32 CXX_FLAGS=-m32 LD_FLAGS=-m32
make
sudo make install

Install EMSDK

https://emscripten.org/docs/tools_reference/emsdk.html

Build and Run

Linux

• Build
./build.sh

All binaries are in "out", which contains "host_tool", "lvgl_native_ui_app", "ui_app.wasm", "ui_app_lvgl_compatible" and "wasm_runtime_wgl".

Run native Linux application

./lvgl_native_ui_app

Run WASM VM Linux applicaton & install WASM APP

First start wasm_runtime_wgl in server mode.

./wasm_runtime_wgl -s
Then install wasm APP use host tool.
./host_tool -i ui_app -f ui_app.wasm
./host_tool -i ui_app -f ui_app_compatible.wasm

Zephyr

WASM VM and native extension method can be built into Zephyr, Then we can install wasm app into STM32.

• Build WASM VM into Zephyr system

  a. clone zephyr source code
Refer to Zephyr getting started.

https://docs.zephyrproject.org/latest/getting_started/index.html
west init zephyrproject
cd zephyrproject
west update
b. copy samples
cd zephyr/samples/
cp -a <wamr_root>samples/gui/wasm-runtime-wgl wasm-runtime-wgl
cd wasm-runtime-wgl/zephyr_build
c. create a link to wamr core
ln -s <wamr_root>/core core
d. build source code
mkdir build && cd build
source ../../../../zephyr-env.sh
cmake -GNinja -DBOARD=nucleo_f746zg ..
ninja flash

Test on STM32 NUCLEO_F767ZI with ILI9341 Display with XPT2046 touch

Hardware Connections

+-------------------+-+------------------+
|NUCLEO-F767ZI       | ILI9341  Display  |
+-------------------+-+------------------+
| CN7.10             |         CLK       |
+-------------------+-+------------------+
| CN7.12             |         MISO      |
+-------------------+-+------------------+
| CN7.14             |         MOSI      |
+-------------------+-+------------------+
| CN11.1             | CS1 for ILI9341   |
+-------------------+-+------------------+
| CN11.2             |         D/C       |
+-------------------+-+------------------+
| CN11.3             |         RESET     |
+-------------------+-+------------------+
| CN9.25             |    PEN interrupt  |
+-------------------+-+------------------+
| CN9.27             |  CS2 for XPT2046  |
+-------------------+-+------------------+
| CN10.14            |    PC UART RX     |
+-------------------+-+------------------+
| CN11.16            |    PC UART RX     |
+-------------------+-+------------------+

Install WASM application to Zephyr using host_tool

First, connect PC and STM32 with UART. Then install to use host_tool.

./host_tool -D /dev/ttyUSBXXX -i ui_app -f ui_app.wasm