[ESP32_lvgl]Use LVGL with Micropython for ESP32 devBoard
Table of contents:
[TOC]
Table of contents:
3.1 Build micropython for Linux port (optional for newbie):
3.2 Building lv_micropython micropython fork for ESP32 port:
[3.2.1 install the ESP-IDF sdk](#321-install-the-esp-idf-sdk)
[Get ESP-IDF v4.2](#get-esp-idf-v42)
[Set up the environment variables](#set-up-the-environment-variables)
[3.2.2 Build the `lv_micropython` firmware](#322-build-the-lvmicropython-firmware)
[3.2.3 Flashing the `lv_micropython` firmware](#323-flashing-the-lvmicropython-firmware)
[3.2.4 Getting a Python prompt on the device](#324-getting-a-python-prompt-on-the-device)
4 Confiture wifi and use the board Reference and read more
First, thanks for this blog post: Micropython + LittlevGL written by amirgon on Feb, 2019.
Micropython Binding for LittlevGL (lv_binding_micropython) was designed to make it simple to use LittlevGL with Micropython. It plays as a bridge between micropython and lvgl libraries.
In principle lv_binding_micropython can support any micropython fork.
To add lv_binding_micropython to some Micropython fork you need to add lv_binding_micropython under Micropython lib as a git submodule.
Note: In this blog, all the implementations, commands and configurations were tested in Ubuntu20.04 virtual machine.
1 Some basic concepts
Before continue, we need to know some concepts:
what is a micropython fork?
a fork is like a unix distribution. or a micropython that complied/built from fork-and-modified code. “There are many micropython forks for a variety of systems and hardware platforms not supported in the mainline.” – wikipedia_page.
What is a git submodule?
In Git you can add a submodule to a repository. This is basically “a repository embedded in your main repository”. A git submodule is a record within a host git repository that points to a specific commit in another external repository.
How to add some repository under Micropython lib as a git submodule?
You can refer to
Managing Python dependencies with git submodulesand the commands they used shows you some concepts about submodule:git submodule add {github_repo} {local_path}Example:
git submodule add https://github.com/Kif11/logger modules/loggeror:
git submodule add https://github.com/lvgl/lvgl libs/lvglTo understand the submodule, you can see this picture:
what is micropython binding module?
In order to have access to C libraries from Python, a dynamic-link library can be written in C in such a way that
CPythonwill treat it as a module (you will be able to import it in your Python programs). The Python/C API allows the library to define functions that are written in C but still callable from Python. The API is very powerful and provides functions to manipulate all Python data types and access the internals of the interpreter.I didn’t find accureate definitions about micropython binding module, however, readers can guess that the binding module should be a C/python bridge library.
For more info, refer: https://stackoverflow.com/questions/10202306/python-bindings-how-does-it-work
what is a micropython port?
A port will typically contain definitions for multiple “boards”, each of which is a specific piece of hardware that that port can run on, e.g. a development kit or device.
So,
Before compile the lvgl_contained micropython, you need to do:
- add some lines to Micropython Makefile in order to create LittlevGL Binding module
- add the new lvgl module to Micropython by editing mpconfigport.h, in order to compile LittlevGL
ref: MicroPython external C modules
2 The one: lv_micropython
As an example, Amirgon has created the lv_micropython - a Micropython fork with LittlevGL binding. lv_micropython usually be used directly by developers. Let’s see how to use it for ESP32 board. Can use it as it is, or as an example of how to integrate LittlevGL with Micropython.
lv_micropython can currently be used with LittlevGL on the unix port and on the ESP32 port.
LittlevGL needs drivers for the display and for the input device. The Micropython binding contains some example drivers that are registered and used on lv_micropython:
- SDL unix drivers (display and mouse)
- ILI9341 driver for ESP32.
- Raw Resistive Touch for ESP32 (ADC connected to screen directly, no touch IC)
For details about the lv_micropython: https://github.com/lvgl/lv_micropython
3 Quick use of lv_micropython
First, testing the building for Unix(Linux) port:
3.1 Build micropython for Linux port (optional for newbie):
Here, I tested all the commands below on a virtual machine running Ubuntu 20.04.
sudo apt-get install build-essential libreadline-dev libffi-dev git pkg-config libsdl2-2.0-0 libsdl2-dev python3.7 parallel
251MB will be occupied.
cd ~/Downloads
git clone https://github.com/lvgl/lv_micropython.git
cd lv_micropython
git submodule update –init –recursive lib/lv_bindings
waiting for the updating of submodules
make -C mpy-cross
it shows:
make: Entering directory '/home/user/Downloads/lv_micropython/mpy-cross'
Use make V=1 or set BUILD_VERBOSE in your environment to increase build verbosity.
LVGL-GEN build/lvgl/lv_mpy.c
cp ../lib/lv_bindings/driver/png/lodepng/lodepng.cpp build/lodepng/lodepng.c
LODEPNG-GEN build/lodepng/mp_lodepng.c
mkdir -p build/genhdr
GEN build/genhdr/mpversion.h
GEN build/genhdr/moduledefs.h
...
mkdir -p build/py/
mkdir -p build/shared/runtime/
CC ../py/mpstate.c
CC ../py/nlr.c
CC ../py/nlrx86.c
CC ../py/nlrx64.c
CC ../py/nlrthumb.c
...
CC main.c
CC gccollect.c
CC ../shared/runtime/gchelper_generic.c
LINK mpy-cross
text data bss dec hex filename
410368 37952 896 449216 6dac0 mpy-cross
make: Leaving directory '/home/user/Downloads/lv_micropython/mpy-cross'
make -C ports/unix submodules
It shows:
make: Entering directory '/home/user/Downloads/lv_micropython/ports/unix'
Use make V=1 or set BUILD_VERBOSE in your environment to increase build verbosity.
Updating submodules: lib/axtls lib/berkeley-db-1.xx lib/libffi
Submodule 'lib/axtls' (https://github.com/micropython/axtls.git) registered for path '../../lib/axtls'
Submodule 'lib/berkeley-db-1.xx' (https://github.com/pfalcon/berkeley-db-1.xx) registered for path '../../lib/berkeley-db-1.xx'
Submodule 'lib/libffi' (https://github.com/atgreen/libffi) registered for path '../../lib/libffi'
Cloning into '/home/user/Downloads/lv_micropython/lib/axtls'...
Cloning into '/home/user/Downloads/lv_micropython/lib/berkeley-db-1.xx'...
Cloning into '/home/user/Downloads/lv_micropython/lib/libffi'...
Submodule path '../../lib/axtls': checked out '531cab9c278c947d268bd4c94ecab9153a961b43'
Submodule path '../../lib/berkeley-db-1.xx': checked out '35aaec4418ad78628a3b935885dd189d41ce779b'
Submodule path '../../lib/libffi': checked out 'e9de7e35f2339598b16cbb375f9992643ed81209'
make: Leaving directory '/home/user/Downloads/lv_micropython/ports/unix'
make -C ports/unix
It shows:
make: Entering directory '/home/user/Downloads/lv_micropython/ports/unix'
Use make V=1 or set BUILD_VERBOSE in your environment to increase build verbosity.
LVGL-GEN build-standard/lvgl/lv_mpy.c
cp ../../lib/lv_bindings/driver/png/lodepng/lodepng.cpp build-standard/lodepng/lodepng.c
LODEPNG-GEN build-standard/lodepng/mp_lodepng.c
mkdir -p build-standard/genhdr
GEN build-standard/genhdr/mpversion.h
GEN build-standard/genhdr/moduledefs.h
...
mkdir -p build-standard/build-standard/lvgl/
...
CC ../../lib/lv_bindings/driver/SDL/modSDL.c
CC ../../lib/lv_bindings/driver/linux/modfb.c
LINK micropython
text data bss dec hex filename
1452759 206648 6568 1665975 196bb7 micropython
make: Leaving directory '/home/user/Downloads/lv_micropython/ports/unix'
You can run the build result by:
./ports/unix/micropython
For further testing, comment out the last three lines for /lib/lv_bindings/examples/advanced_demo.py, and run the demo by the command:
./ports/unix/micropython ./lib/lv_bindings/examples/advanced_demo.py
You’ll see a window shows up:
Congrates!
3.2 Building lv_micropython micropython fork for ESP32 port:
For building a port of MicroPython to the Espressif ESP32 series of microcontrollers. It uses the ESP-IDF framework. The MicroPython runs as a task under FreeRTOS.
MicroPython on ESP32 requires the Espressif IDF version 4 (IoT development framework, aka SDK). The ESP-IDF includes the libraries and RTOS needed to manage the ESP32 microcontroller, as well as a way to manage the required build environment and toolchains needed to build the firmware.
3.2.1 install the ESP-IDF sdk
To install the ESP-IDF the full instructions can be found at the Espressif Getting Started guide: installation step by step.
For my vm ubuntu, I follow the installing prerequests tools with next command:
sudo apt-get install git wget flex bison gperf python3 python3-pip python3-setuptools cmake ninja-build ccache libffi-dev libssl-dev dfu-util
Adding user to dialout on Linux
sudo usermod -a -G dialout $USER
Get ESP-IDF v4.2
mkdir -p ~/esp
cd ~/esp
git clone -b release/v4.2 –recursive https://github.com/espressif/esp-idf.git
Set up the tools for esp32
cd ~/esp/esp-idf
./install.sh esp32
Set up the environment variables
need to add tools to the PATH environment variable. ESP-IDF provides export.sh script which does that.
. $HOME/esp/esp-idf/export.sh
add the below line into ~/.bashrc, then restart terminal.
alias get_idf='. $HOME/esp/esp-idf/export.sh'
3.2.2 Build the lv_micropython firmware
cd to the root of this repository:
cd $HOME/Downloads/lv_micropython
make the mpy-cross
make -C mpy-cross
Then to build MicroPython for the ESP32 run:
cd ports/esp32
make submodules
you’ll see:
git submodule update --init ../../lib/berkeley-db-1.xx
make
or, for ILI9341 screen driver compatible:
cd $HOME/Downloads/lv_micropython
make -C ports/esp32 LV_CFLAGS="-DLV_COLOR_DEPTH=16 -DLV_COLOR_16_SWAP=1" BOARD=GENERIC
make -C ports/esp32 deploy
it shows:
idf.py -D MICROPY_BOARD=GENERIC -B build-GENERIC build
Executing action: all (aliases: build)
Running cmake in directory /home/user/Downloads/lv_micropython/ports/esp32/build-GENERIC
Executing "cmake -G Ninja -DPYTHON_DEPS_CHECKED=1 -DESP_PLAT
...
MPY webrepl_setup.py
MPY websocket_helper.py
MPY neopixel.py
GEN /home/user/Downloads/lv_micropython/ports/esp32/build-GENERIC/frozen_content.c
[1447/1447] Generating binary image from built executable
esptool.py v3.1-dev
Merged 2 ELF sections
Generated /home/user/Downloads/lv_micropython/ports/esp32/build-GENERIC/micropython.bin
Project build complete. To flash, run this command:
/home/user/.espressif/python_env/idf4.2_py3.8_env/bin/python ../../../../esp/esp-idf/components/esptool_py/esptool/esptool.py -p (PORT) -b 460800 --before default_reset --after hard_reset --chip esp32 write_flash --flash_mode dio --flash_size detect --flash_freq 40m 0x1000 build-GENERIC/bootloader/bootloader.bin 0x8000 build-GENERIC/partition_table/partition-table.bin 0x10000 build-GENERIC/micropython.bin
or run 'idf.py -p (PORT) flash'
bootloader @0x001000 22576 ( 6096 remaining)
partitions @0x008000 3072 ( 1024 remaining)
application @0x010000 2258256 ( 101040 remaining)
total 2323792
This will produce a combined firmware.bin image in the build-GENERIC/ subdirectory (this firmware image is made up of: bootloader.bin, partitions.bin and micropython.bin).
However I obtains two .bin files:
$ ll build-GENERIC/*.bin
-rw-rw-r-- 1 xxx 2319696 1月 19 20:53 firmware.bin
-rw-rw-r-- 1 xxx 2258256 1月 19 20:53 micropython.bin
3.2.3 Flashing the lv_micropython firmware
on ubuntu, you may need to use this command to add permission for $USER to access the usbSerial port:
sudo adduser $USER dialout
This will add the current user to the dialout group. Login and out it to take effect.
Erase the flash completely:
$ cd $HOME/Downloads/lv_micropython/ports/esp32
$ get_idf
$ make erase
use picocom -b 115200 /dev/ttyUSB0 to test the communication if you meet “connection time out” error when erasing.
after erasing, you’ll see:
Serial port /dev/ttyUSB0
Connecting........_
Chip is ESP32-D0WDQ6 (revision 1)
Features: WiFi, BT, Dual Core, 240MHz, VRef calibration in efuse, Coding Scheme None
Crystal is 40MHz
MAC: 4c:eb:d6:7d:0b:44
Uploading stub...
Running stub...
Stub running...
Changing baud rate to 460800
Changed.
Erasing flash (this may take a while)...
Chip erase completed successfully in 9.2s
Hard resetting via RTS pin...
Done
Tips: You may meet the “time out connecting fatal” when using make erase in ubuntu guest vm. I finally use the ESP-IDF vsCode extension to successfully erase the flash of my ESP32 DevKit_v1_board.
To flash the MicroPython firmware to your ESP32 use:
$ make deploy
you’ll see:
idf.py -D MICROPY_BOARD=GENERIC -B build-GENERIC -p /dev/ttyUSB0 -b 460800 flash
Executing action: flash
Running ninja in directory /home/user/Downloads/lv_micropython/ports/esp32/build-GENERIC
Executing "ninja flash"...
[2/5] Performing build step for 'bootloader'
ninja: no work to do.
[2/3] cd /home/user/esp/esp-idf/components/esptool_py && /usr/bin/cm...C" -P /home/user/esp/esp-idf/components/esptool_py/run_esptool.cmake
esptool.py esp32 -p /dev/ttyUSB0 -b 460800 --before=default_reset --after=hard_reset write_flash --flash_mode dio --flash_freq 40m --flash_size 4MB 0x8000 partition_table/partition-table.bin 0x1000 bootloader/bootloader.bin 0x10000 micropython.bin
esptool.py v3.1-dev
Serial port /dev/ttyUSB0
Connecting....
Chip is ESP32-D0WDQ6 (revision 1)
Features: WiFi, BT, Dual Core, 240MHz, VRef calibration in efuse, Coding Scheme None
Crystal is 40MHz
MAC: 4c:eb:d6:7d:0b:44
Uploading stub...
Running stub...
Stub running...
Changing baud rate to 460800
Changed.
Configuring flash size...
Flash will be erased from 0x00008000 to 0x00008fff...
Flash will be erased from 0x00001000 to 0x00006fff...
Flash will be erased from 0x00010000 to 0x00237fff...
Compressed 3072 bytes to 117...
Writing at 0x00008000... (100 %)
Wrote 3072 bytes (117 compressed) at 0x00008000 in 0.1 seconds (effective 476.7 kbit/s)...
Hash of data verified.
Compressed 22576 bytes to 14067...
Writing at 0x00001000... (100 %)
Wrote 22576 bytes (14067 compressed) at 0x00001000 in 0.8 seconds (effective 221.6 kbit/s)...
Hash of data verified.
Compressed 2258256 bytes to 1423672...
Writing at 0x00010000... (1 %)
Writing at 0x000194cc... (2 %)
Writing at 0x000210ff... (3 %)
...
Writing at 0x00231716... (100 %)
Wrote 2258256 bytes (1423672 compressed) at 0x00010000 in 52.4 seconds (effective 344.7 kbit/s)...
Hash of data verified.
Leaving...
Hard resetting via RTS pin...
Done
Note: the above “make” commands are thin wrappers (like and alias) for the underlying idf.py build tool that is part of the ESP-IDF. You can instead use idf.py directly.
3.2.4 Getting a Python prompt on the device
You can get a prompt via the serial port, via /dev/ttyUART0, which is the same UART that is used for programming the firmware. The baudrate for the REPL is 115200 and you can use a tools such as:
$ picocom -b 115200 /dev/ttyUSB0
or
$ miniterm.py /dev/ttyUSB0 115200
Tips:
ctrl-A, ctrl-Xwill terminatepicocomsession.You can also use
idf.py monitor.
After get python prompt, type help() shows the Control Commands.
4 Confiture wifi and use the board
go to link configure wifi and use the board
Reference and read more
Reference: https://github.com/lvgl/lv_micropython/blob/master/ports/esp32/README.md
more info about micropython lvgl development: https://github.com/lvgl/lv_micropython
more info about replanting on ARM board: 支持LVGL的micropython固件编译（二）arm板移植 (in Chinese)
Issue fixing after flashing
I met RuntimeError: ili9341 micropython driver requires defining LV_COLOR_DEPTH=16 when using REPL with my esp32_TFTscreen board driven by ILI9341.
Add the next configure into command for firmware building. Refer: https://github.com/lvgl/lv_micropython/README.md
LV_CFLAGS="-DLV_COLOR_DEPTH=16 -DLV_COLOR_16_SWAP=1"
Refer 3.2.2 Build the lv_micropython firmware
you may need to delete the build-XXX folder under lv_micropython/ports/esp32/ before re-build the firmware.bin
>>> from ili9XXX import ili9341
>>> disp = ili9341()
Single buffer
ILI9341 initialization completed
Enable backlight
When you see the above lines in REPL, the LV_COLOR_DEPTH=16 parameter for ILI9341 is successfully added.
Finally giving up
Micropython developing lvgl powered UI for ESP32 seems a joke.
I spent one hour for running an example micropython lvgl code, but failed. Nothing shown on TFT screen.
This experience of building / deploying micropython tells me that micropython is a tool, if large lib such as lvgl is depended, your micropython project will be tough.
c++ is still the right way to play with embedded projects. micropython is a tool for simple control and simple logic.