LVGL binding for Micropython

---

I have tried to make this as simple as possible for paople to use. There are some glitches still in it I am sure. If you come across an issue please let me know.

I am still in development mode for the unix port. I am writing an SDL driver that conforms To the rest of the driver framework. I have started working on writing the frameworks for the different indev (input) types that LVGL supports. The frameworks are written to make it easier to write display and input drivers for the binding.

New changes

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ALL MCU's I have started to nail down a commoin API for the indev drivers, specifically the pointer/touch drivers. In order to do this I had to change the handling of the type of bus being used. Just like the displays the touch/pointer driver IC's can sometimes accept an SPI bus or an I2C bus as the way to communicate. Instead of having to duplicate code for these driver IC's I decided to make the software driver completely unaware of the bus that is being used. To do this i made the I2C driver work in the same manner as the SPI driver.

Here is a code example of how to use the I2C bus with a touch driver.

from i2c import I2C
import ft5x06

i2c_bus = I2C.Bus(host=1, sda=10, sdl=11)
touch_i2c = I2C.Device(i2c_bus, ft5x06.I2C_ADDR, ft5x06.BITS)
touch = ft5x06.FT5x06(touch_i2c)

If a touch driver doesn't have the variable I2C_ADDR or BITS then that driver doesn't support the I2C bus.

ESP32-ALL

• --optimize-size: If you are having an issue with getting the firmware to fit into your esp32 or if space is more of a concern than speed you can set this command line option. This will tell the compiler that the firmware size is more important than performance and the compiled binary will be smaller as a result.

• --flash-size={size}: Flash sizes that are able to be used are 4, 8, 16, 32, 64 and 128 across all variants of the ESP32. It is up to the user to know what their board is using.

• --ota: If you want to set the partitions so you can do an over the air update of the firmware. I do want to note that this does take up twice as much application storage space. This feature applies to any board.

• CONFIG_*={value}: You can alter the config settings of the esp-idf by using these settings. Refer to the ESP-IDF documentation for further information

• SPI: The machine.SPI class has undergone a HUGE change. It is now split into 2 pieces. machine.SPI.Bus and machine.SPI.Device They exactly what they seem. It is easier to show a code example then it is to explain it.

  from machine import SPI

  spi_bus = SPI.Bus( host=1, mosi=15, miso=16, sck=10 )

  spi_device = SPI.Device( spi_bus=spi_bus, freq=10000000, cs=3, polarity=0, phase=0, bits=8, first_bit=SPI.MSB )

  if you want to delete a device from being used you have to deinit it first

  and then you can delete it

  spi_device.deinit() del spi_device

  if you want to stop using a bus and all devices attached to it

  del spi_bus del spi_device

  The SPI.Bus instance you need to pass to machine.SDCard, lcd_bus.SPIBus

  and any of the touch drivers that use SPI.

All methods that existed for the original machine.SPI are available in the machine.SPI.Device class. They work exactly how they did before.

Confirmed working

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• Display Bus

  • ESP32 SPI
  • ESP32 RGB
  • ESP32 I8080

• Memory

  • SRAM
  • SRAM DMA
  • PSRAM (SPIRAM)
  • PSRAM (SPIRAM) DMA

• Display IC

  • ST7796
  • ST7789
  • ILI9341
  • SDL
  • RGB
  • ILI9488

• Touch IC

  • XPT2046
  • GT911
  • Mouse
  • FT6x06
  • FT5x06

Build Instructions

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I have changed the design of the binding so it is no longer a dependancy of MicroPython. Instead MicroPython is now a dependency of the binding. By doing this I have simplified the process up updating the MicroPython version. Only small changes are now needed to support newer versions of MicroPython.

In order to make this all work I have written a Python script that handles Building the binding. The only prerequesits are that you have a C compiler installed (gcc, clang, msvc) and the necessary support libs.

Requirements

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compiling for ESP32

• Ubuntu (Linux): you can install all of these using apt-get install

  • build-essential
  • cmake
  • ninja-build
  • python

• macOS

  • xcode-select -–install
  • brew install cmake
  • brew install ninja
  • brew install python

Compiling for RP2

• Ubuntu (Linux): you can install all of these using apt-get install

  • build-essential
  • cmake
  • ninja-build
  • python
  • gcc-arm-none-eabi
  • libnewlib-arm-none-eabi

• macOS

  • command xcode-select–install
  • brew install make
  • brew install cmake
  • brew install ninja
  • brew install python
  • brew install armmbed/formulae/arm-none-eabi-gcc

• Windows

  • Not yet supported

Compiling for STM32:

• Ubuntu (Linux): you can install all of these using apt-get install

  • gcc-arm-none-eabi
  • libnewlib-arm-none-eabi: maybe??
  • build-essential
  • ninja-build
  • python

• macOS

  • command xcode-select–install
  • brew install make
  • brew install ninja
  • brew install python
  • brew install armmbed/formulae/arm-none-eabi-gcc

• Windows

  • Not yet supported

Compiling for Ubuntu (Linux): you can install all of these using apt-get install

• build-essential
• libffi-dev
• pkg-config
• cmake
• ninja-build
• gnome-desktop-testing
• libasound2-dev
• libpulse-dev
• libaudio-dev
• libjack-dev
• libsndio-dev
• libx11-dev
• libxext-dev
• libxrandr-dev
• libxcursor-dev
• libxfixes-dev
• libxi-dev
• libxss-dev
• libxkbcommon-dev
• libdrm-dev
• libgbm-dev
• libgl1-mesa-dev
• libgles2-mesa-dev
• libegl1-mesa-dev
• libdbus-1-dev
• libibus-1.0-dev
• libudev-dev
• fcitx-libs-dev
• libpipewire-0.3-dev
• libwayland-dev
• libdecor-0-dev

Compiling for macOS

• command xcode-select–install
• brew install libffi
• brew install ninja
• brew install make

Compiling for Windows

• not supported yet

Build Target

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You are also going to need Python >= 3.10 installed for all builds

There is a single entry point for all builds. That is the make.py script in the root of the repository.

The first argument is positional and it must be one of the following.

• esp32
• windows
• macOS
• stm32
• unix
• rp2
• renesas-ra
• nrf
• mimxrt
• samd

Build Options

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The next few arguments are optional to some degree.

• submodules**: collects all needed dependencies to perform the build
• clean: cleans the build environment
• mpy_cross**: compiles mpy-cross this is not used for all builds. if it is not supported it will do nothing.

**must be run only one time when the build is intially started. after that you will not need to add these arguments. There is internal checking that is done to see if the argument needs to be carried out. So you can also optionally leave it there if you want.

Identifying the MCU board

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The next group of options are going to be port specific, some may have them and some may not.

• BOARD: The MCU to build for. This follows the same symantics as what MIcroPython uses.
• BOARD_VARIANT: if there is a variation of the board that it to be compiled for.

I will go into specifics for what what boards and variants are available for a specific port a little bit further down.

Additional Arguments

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• LV_CFLAGS: additional compiler flags that get passed to the LVGL build only.
• FROZEN_MANIFEST: path to a custom frozen manifest file
• DISPLAY: this can either be the file name (less the .py) of a display driver that is in the driver/display folder or it can be the absolute path to your own custom driver (with the .py extension)
• INDEV: this can either be the file name (less the .py) of an indev driver that is in the driver/indev folder or it can be the absolute path to your own custom driver (with the .py extension)

ESP32 specific options

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• --skip-partition-resize: do not resize the firmware partition

• --partition-size: set a custom firmware partition size

• --octal-flash ¹: This is only available for the 16mb flash and the 32mb flash

• --flash-size ² ³: This is how much flash storage is available.

  Allowed Values are:

  • ESP32-S3: 4, 8, 16 and 32 (default is 8)
  • ESP32-S2: 2 and 4 (default is 4)
  • ESP32: 4, 8 and 16 (default is 4) , The default is 8.

¹ Available for the ESP32-S3 when BOARD_VARIANT is set to SPIRAM_OCT
² Available for the ESP32, ESP32-S2 and ESP32-S3
³ Available only when BOARD_VARIANT is set to SPIRAM or SPIRAM_OCT

Boards & Board Variants

---

• esp32: BOARD=

  • ARDUINO_NANO_ESP32
  • ESP32_GENERIC
    • BOARD_VARIANT=D2WD
    • BOARD_VARIANT=OTA
  • ESP32_GENERIC_C3
  • ESP32_GENERIC_S2
  • ESP32_GENERIC_S3
    • BOARD_VARIANT=SPIRAM_OCT
  • LILYGO_TTGO_LORA32
  • LOLIN_C3_MINI
  • LOLIN_S2_MINI
  • LOLIN_S2_PICO
  • M5STACK_ATOM
  • OLIMEX_ESP32_POE
  • SIL_WESP32
  • UM_FEATHERS2
  • UM_FEATHERS2NEO
  • UM_FEATHERS3
  • UM_NANOS3
  • UM_PROS3
  • UM_TINYPICO
  • UM_TINYS2
  • UM_TINYS3
  • UM_TINYWATCHS3

• windows: VARIANT=

  • dev
  • stndard

• stm32: BOARD=

  • ADAFRUIT_F405_EXPRESS
  • ARDUINO_GIGA
  • ARDUINO_NICLA_VISION
  • ARDUINO_PORTENTA_H7
  • B_L072Z_LRWAN1
  • B_L475E_IOT01A
  • CERB40
  • ESPRUINO_PICO
  • GARATRONIC_NADHAT_F405
  • GARATRONIC_PYBSTICK26_F411
  • HYDRABUS
  • LEGO_HUB_NO6
  • LEGO_HUB_NO7
  • LIMIFROG
  • MIKROE_CLICKER2_STM32
  • MIKROE_QUAIL
  • NETDUINO_PLUS_2
  • NUCLEO_F091RC
  • NUCLEO_F401RE
  • NUCLEO_F411RE
  • NUCLEO_F412ZG
  • NUCLEO_F413ZH
  • NUCLEO_F429ZI
  • NUCLEO_F439ZI
  • NUCLEO_F446RE
  • NUCLEO_F722ZE
  • NUCLEO_F746ZG
  • NUCLEO_F756ZG
  • NUCLEO_F767ZI
  • NUCLEO_G0B1RE
  • NUCLEO_G474RE
  • NUCLEO_H563ZI
  • NUCLEO_H723ZG
  • NUCLEO_H743ZI
  • NUCLEO_H743ZI2
  • NUCLEO_L073RZ
  • NUCLEO_L152RE
  • NUCLEO_L432KC
  • NUCLEO_L452RE
  • NUCLEO_L476RG
  • NUCLEO_L4A6ZG
  • NUCLEO_WB55
  • NUCLEO_WL55
  • OLIMEX_E407
  • OLIMEX_H407
  • PYBD_SF2
  • PYBD_SF3
  • PYBD_SF6
  • PYBLITEV10
  • PYBV10
  • PYBV11
  • PYBV3
  • PYBV4
  • SPARKFUN_MICROMOD_STM32
  • STM32F411DISC
  • STM32F429DISC
  • STM32F439
  • STM32F4DISC
  • STM32F769DISC
  • STM32F7DISC
  • STM32H573I_DK
  • STM32H7B3I_DK
  • STM32L476DISC
  • STM32L496GDISC
  • USBDONGLE_WB55
  • VCC_GND_F407VE
  • VCC_GND_F407ZG
  • VCC_GND_H743VI

• unix: VARIANT=

  • coverage
  • minimal
  • nanbox
  • standard

• rp2: BOARD=

  • ADAFRUIT_FEATHER_RP2040

  • ADAFRUIT_ITSYBITSY_RP2040

  • ADAFRUIT_QTPY_RP2040

  • ARDUINO_NANO_RP2040_CONNECT

  • GARATRONIC_PYBSTICK26_RP2040

  • NULLBITS_BIT_C_PRO

  • PIMORONI_PICOLIPO_16MB

  • PIMORONI_PICOLIPO_4MB

  • PIMORONI_TINY2040

  • POLOLU_3PI_2040_ROBOT

  • POLOLU_ZUMO_2040_ROBOT

  • RPI_PICO

  • RPI_PICO_W

  • SIL_RP2040_SHIM

  • SPARKFUN_PROMICRO

  • SPARKFUN_THINGPLUS

  • W5100S_EVB_PICO

  • W5500_EVB_PICO

  • WEACTSTUDIO

    • BOARD_VARIANT=FLASH_2M
    • BOARD_VARIANT=FLASH_4M
    • BOARD_VARIANT=FLASH_8M

  • renesas-ra: BOARD=

    • ARDUINO_PORTENTA_C33
    • EK_RA4M1
    • EK_RA4W1
    • EK_RA6M1
    • EK_RA6M2
    • RA4M1_CLICKER
    • VK_RA6M5

  • nrf: BOARD=

    • ACTINIUS_ICARUS
    • ARDUINO_NANO_33_BLE_SENSE
    • ARDUINO_PRIMO
    • BLUEIO_TAG_EVIM
    • DVK_BL652
    • EVK_NINA_B1
    • EVK_NINA_B3
    • FEATHER52
    • IBK_BLYST_NANO
    • IDK_BLYST_NANO
    • MICROBIT
    • NRF52840_MDK_USB_DONGLE
    • PARTICLE_XENON
    • PCA10000
    • PCA10001
    • PCA10028
    • PCA10031
    • PCA10040
    • PCA10056
    • PCA10059
    • PCA10090
    • SEEED_XIAO_NRF52
    • WT51822_S4AT

  • mimxrt: BOARD=

    • ADAFRUIT_METRO_M7
    • MIMXRT1010_EVK
    • MIMXRT1015_EVK
    • MIMXRT1020_EVK
    • MIMXRT1050_EVK
    • MIMXRT1060_EVK
    • MIMXRT1064_EVK
    • MIMXRT1170_EVK
    • OLIMEX_RT1010
    • SEEED_ARCH_MIX
    • TEENSY40
    • TEENSY41

  • samd: BOARD=

    • ADAFRUIT_FEATHER_M0_EXPRESS
    • ADAFRUIT_FEATHER_M4_EXPRESS
    • ADAFRUIT_ITSYBITSY_M0_EXPRESS
    • ADAFRUIT_ITSYBITSY_M4_EXPRESS
    • ADAFRUIT_METRO_M4_EXPRESS
    • ADAFRUIT_TRINKET_M0
    • MINISAM_M4
    • SAMD21_XPLAINED_PRO
    • SEEED_WIO_TERMINAL
    • SEEED_XIAO_SAMD21
    • SPARKFUN_SAMD51_THING_PLUS

Build Command Examples

---

build with submodules and mpy_cross

python3 make.py esp32 submodules clean mpy_cross BOARD=ESP32_GENERIC_S3 BOARD_VARIANT=SPIRAM_OCT DISPLAY=st7796 INDEV=gt911

build without submodules or mpy_cross

python3 make.py esp32 clean BOARD=ESP32_GENERIC_S3 BOARD_VARIANT=SPIRAM_OCT DISPLAY=st7796 INDEV=gt911

I always recommend building with the clean command, this will ensure you get a good fresh build.

NOTE: There is a bug in the ESP32 build. The first time around it will fail saying that one of the sumbodules is not available. Run the build again with the submodules argument in there and then it will build fine. For the life of me I cam not able to locate where the issue is stemming from. I will find it eventually.

I will provide directions on how to use the driver framework and also the drivers that are included with the binding in the coming weeks.

SDL fpr Unix is working properly. Make sure you review the requirements needed to compile for unix!!! The build system compiles the latest version of SDL2 so the list is pretty long for the requirements.

To build for Unix use the following build command

python3 make.py unix clean DISPLAY=sdl_display INDEV=sdl_pointer

Couple of notes:

• I recommend making 2 frame buffers as seen in the code example below. This will give you better performance.
• DO NOT enable LV_USE_DRAW_SDL, I have not written code to allow for it's use (yet).
• I recommend running lv.task_handler once every 5 milliseconds, shorter than that and you will have a lot of CPU time comsumed. Linger than that and your mouse response is not going to be great.

Here is some example code for the unix port

from micropython import const  # NOQA

_WIDTH = const(480)
_HEIGHT = const(320)

_BUFFER_SIZE = _WIDTH * _HEIGHT * 3

import lcd_bus  # NOQA

bus = lcd_bus.SDLBus(flags=0)

buf1 = bus.allocate_framebuffer(_BUFFER_SIZE, 0)
buf2 = bus.allocate_framebuffer(_BUFFER_SIZE, 0)

import lvgl as lv  # NOQA
import sdl_display  # NOQA

lv.init()

display = sdl_display.SDLDisplay(
    data_bus=bus,
    display_width=_WIDTH,
    display_height=_HEIGHT,
    frame_buffer1=buf1,
    frame_buffer2=buf2,
    color_space=lv.COLOR_FORMAT.RGB888
)

display.init()

import sdl_pointer

mouse = sdl_pointer.SDLPointer()

scrn = lv.screen_active()
scrn.set_style_bg_color(lv.color_hex(0x000000), 0)

slider = lv.slider(scrn)
slider.set_size(300, 25)
slider.center()


import task_handler
# the duration needs to be set to 5 to have a good response from the mouse.
# There is a thread that runs that facilitates double buffering. 
th = task_handler.TaskHandler(duration=5)

The touch screen drivers will handle the rotation that you set to the display. There is a single caviat to this. You MUST set up and initilize the display then create the touch drivers and after that has been done you can set the rotation. The touch driver must exist prior to the display rotation being set.

For the ESP32 SOC's there is NVRAM that is available to store data in. That data is persistant between restarts of the ESP32. This feature is pur to use to store calibration data for the touch screen. In the exmaple below it shows how to properly create a display driver and touch driver and how to set the rotation and also the calibration storage.

import lcd_bus

from micropython import const

# display settings
_WIDTH = const(320)
_HEIGHT = const(480)
_BL = const(45)
_RST = const(4)
_DC = const(0)
_WR = const(47)
_FREQ = const(20000000)
_DATA0 = const(9)
_DATA1 = const(46)
_DATA2 = const(3)
_DATA3 = const(8)
_DATA4 = const(18)
_DATA5 = const(17)
_DATA6 = const(16)
_DATA7 = const(15)
_BUFFER_SIZE = const(30720)

_SCL = const(5)
_SDA = const(6)
_TP_FREQ = const(100000)


display_bus = lcd_bus.I80Bus(
    dc=_DC,
    wr=_WR,
    freq=_FREQ,
    data0=_DATA0,
    data1=_DATA1,
    data2=_DATA2,
    data3=_DATA3,
    data4=_DATA4,
    data5=_DATA5,
    data6=_DATA6,
    data7=_DATA7
)

fb1 = display_bus.allocate_framebuffer(_BUFFER_SIZE, lcd_bus.MEMORY_INTERNAL | lcd_bus.MEMORY_DMA)
fb2 = display_bus.allocate_framebuffer(_BUFFER_SIZE, lcd_bus.MEMORY_INTERNAL | lcd_bus.MEMORY_DMA)


import st7796  # NOQA
import lvgl as lv  # NOQA

lv.init()

display = st7796.ST7796(
    data_bus=display_bus,
    frame_buffer1=fb1,
    frame_buffer2=fb2,
    display_width=_WIDTH,
    display_height=_HEIGHT,
    backlight_pin=_BL,
    # reset=_RST,
    # reset_state=st7796.STATE_LOW,
    color_space=lv.COLOR_FORMAT.RGB565,
    color_byte_order=st7796.BYTE_ORDER_BGR,
    rgb565_byte_swap=True,
)

import i2c  # NOQA
import task_handler  # NOQA
import ft6x36  # NOQA
import time  # NOQA

display.init()

i2c_bus = i2c.I2CBus(scl=_SCL, sda=_SDA, freq=_TP_FREQ, use_locks=False)
indev = ft6x36.FT6x36(i2c_bus)

display.invert_colors()

if not indev.is_calibrated:
    display.set_backlight(100)
    indev.calibrate()

# you want to rotate the display after the calibration has been done in order
# to keep the corners oriented properly.
display.set_rotation(lv.DISPLAY_ROTATION._90)

display.set_backlight(100)

th = task_handler.TaskHandler()

scrn = lv.screen_active()
scrn.set_style_bg_color(lv.color_hex(0x000000), 0)

slider = lv.slider(scrn)
slider.set_size(300, 50)
slider.center()

label = lv.label(scrn)
label.set_text('HELLO WORLD!')
label.align(lv.ALIGN.CENTER, 0, -50)

You are able to force the calibration at any time by calling indev.calibrate() regardless of what indev.is_calibrate returns. This makes it possible to redo the calibration by either using a pin that you can check the state of or through a button in your UI that you provide to the user.

Thank again and enjoy!!

NOTE: On ESP32-S3, SPI host 0 and SPI host 1 share a common SPI bus. The main Flash and PSRAM are connected to the host 0. It is recommended to use SPI host 2 when connecting an SPI device like a display that is going to utilize the PSRAM for the frame buffer.

Bit orders are a tuple of durations. The first 2 numbers define a bit as 0 and the second 2 define a bit as 1. Negitive numbers are the duration to hold low and positive are for how long to hold high "Res" or "Reset" is sent at the end of the data.

Name	Bit 0 Duration 1	Bit 0 Duration 2	Bit 1 Duration 1	Bit 1 Duration 2	Res	Order
APA105 APA109 APA109 SK6805 SK6812 SK6818	300	-900	600	-600	-800	GRB
WS2813	300	-300	750	-300	-300	GRB
APA104	350	-1360	1360	-350	-240	RGB
SK6822	350	-1360	1360	-350	-500	RGB
WS2812	350	-800	700	-600	-5000	GRB
WS2818A WS2818B WS2851 WS2815B WS2815 WS2811 WS2814	220	-580	580	-220	-280	RGB
WS2818	220	-750	750	-220	-300	RGB
WS2816A WS2816B WS2816C	200	-800	520	-480	-280	GRB
WS2812B	400	-850	800	-450	-5000	GRB
SK6813	240	-800	740	-200	-800	GRB