Micropython + lvgl

For information abound Micropython lvgl bindings please refrer to lv_bindings/README.md

See also Micropython + LittlevGL blog post.

Build Instructions

1. sudo apt-get install build-essential libreadline-dev libffi-dev git pkg-config libsdl2-2.0-0 libsdl2-dev python
2. git clone --recurse-submodules https://github.com/littlevgl/lv_micropython.git
3. cd lv_micropython
4. make -C ports/unix/
5. ./ports/unix/micropython

For ESP32 port

Please set ESPIDF parameter for the esp-idf install dir. It needs to match Micropython expected esp-idf, otherwise a warning will be displayed (and build will probably fail) For more details refer to Setting up the toolchain and ESP-IDF

When using IL9341 driver, the color depth and swap mode need to be set to match ILI9341. This can be done from the command line. Here is the command to build ESP32 + LittlevGL which is compatible with ILI9341 driver:

make -C mpy-cross
make -C ports/esp32 LV_CFLAGS="-DLV_COLOR_DEPTH=16 -DLV_COLOR_16_SWAP=1" BOARD=GENERIC_SPIRAM PYTHON=python2 deploy

Explanation about the paramters:

• LV_CFLAGS are used to override color depth and swap mode, for ILI9341 compatibility.
  • LV_COLOR_DEPTH=16 is needed if you plan to use the ILI9341 driver.
  • LV_COLOR_16_SWAP=1 is only needed if you plan to use the Pure Micropython Display Driver. Otherwise, remove it.
• BOARD - I use WROVER board with SPIRAM. You can choose other boards from ports/esp32/boards/ directory.
• PYTHON=python2 - depending on your installed pyparsing version, you might or might not need this.
• deploy - make command will create ESP32 port of Micropython, and will try to deploy it through USB-UART bridge.

For more details please refer to Micropython ESP32 README.

For JavaScript port

You need Emscripten installed and working. There are lots of guides about that on the web, but here's the official one.

Once you have Emscripten working, you also need to install the clang package:

1. cd <path to emsdk>
2. Make sure you have installed cmake, and then ./emsdk install clang-tag-e<sdk version>-64bit # for example: clang-tag-e1.38.31-64bit (You can use ./emsdk list to show the available packages)
3. ./emsdk activate clang-tag-e<sdk version>-64bit

Now you can build the JavaScript port.

1. cd <path to lv_micropython>
2. source <path to emsdk>/emsdk_env.sh
3. git checkout lvgl_javascript
4. git submodule update --init --recursive (can be very important!)
5. Build the MicroPython cross-compiler: make -C mpy-cross
6. cd ports/javascript
7. make
8. Run an HTTP server that serves files from the current directory, and then browse to /lvgl_editor.html on the HTTP Server.(Or you can run the build/micropython.js in node)

Super Simple Example

First, LittlevGL needs to be imported and initialized

import lvgl as lv
lv.init()

Then display driver and input driver needs to be registered. Refer to Porting the library for more information. Here is an example of registering SDL drivers on Micropython unix port:

import SDL
SDL.init()

# Register SDL display driver.

disp_buf1 = lv.disp_buf_t()
buf1_1 = bytearray(480*10)
lv.disp_buf_init(disp_buf1,buf1_1, None, len(buf1_1)//4)
disp_drv = lv.disp_drv_t()
lv.disp_drv_init(disp_drv)
disp_drv.buffer = disp_buf1
disp_drv.flush_cb = SDL.monitor_flush
disp_drv.hor_res = 480
disp_drv.ver_res = 320
lv.disp_drv_register(disp_drv)

# Regsiter SDL mouse driver

indev_drv = lv.indev_drv_t()
lv.indev_drv_init(indev_drv) 
indev_drv.type = lv.INDEV_TYPE.POINTER;
indev_drv.read_cb = SDL.mouse_read;
lv.indev_drv_register(indev_drv);

Here is an alternative example, for registering ILI9341 drivers on Micropython ESP32 port:

import lvgl as lv

# Import ESP32 and ILI9341 drivers (advnaces tick count and schedules tasks)

import ILI9341 as ili
import lvesp32

# Initialize the driver and register it to LittlevGL

disp = ili.display(miso=5, mosi=18, clk=19, cs=13, dc=12, rst=4, backlight=2)
disp.init()

# Register display driver 

disp_buf1 = lv.disp_buf_t()
buf1_1 = bytearray(480*10)
lv.disp_buf_init(disp_buf1,buf1_1, None, len(buf1_1)//4)
disp_drv = lv.disp_drv_t()
lv.disp_drv_init(disp_drv)
disp_drv.buffer = disp_buf1
disp_drv.flush_cb = disp.flush
disp_drv.hor_res = 240
disp_drv.ver_res = 320
lv.disp_drv_register(disp_drv)

Now you can create the GUI itself

# Create a screen with a button and a label

scr = lv.obj()
btn = lv.btn(scr)
btn.align(lv.scr_act(), lv.ALIGN.CENTER, 0, 0)
label = lv.label(btn)
label.set_text("Hello World!")

# Load the screen

lv.scr_load(scr)

More information

More info about LittlevGL:

• Website https://littlevgl.com
• GitHub: https://github.com/littlevgl/lvgl

More info about lvgl Micropython bindings:

• https://github.com/littlevgl/lv_bindings/blob/master/README.md

Discussions about the Microptyhon binding: lvgl/lvgl#557

More info about the unix port: https://github.com/micropython/micropython/wiki/Getting-Started#debian-ubuntu-mint-and-variants