LvglOnTheT-watchAndASimulator < IoT_Course

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---+ LVGL on the T-Watch 2020
---++ Introduction

Since the t-watch 2020 has a rather high resolution screen in combination with a touch panel, it is possible to run <b>G</b>raphical <b>U</b>ser <b>I</b>nterfaces (!GUIs) right on the watch. A popular !GUI library is [[https://docs.lvgl.io/v7/en/html/index.html][lvgl ]](<b>Li</b>ght and <b>V</b>ersatile <b>G</b>raphics <b>L</b>ibrary). This library is written in C but !MicroPython [[https://github.com/lvgl/lv_binding_micropython][language bindings]] are available.

In order to bind lvgl into !MicroPython, modifications to the !MicroPython code are needed. Drivers for the t-watch devices must also be integrated into !Micropython. I therefore created the [[https://github.com/uraich/twatch-2020-micropython][twatch-2020-micropython]] github repository integrating all these bits and pieces. This repository is based on
   * https://github.com/OPHoperHPO/lilygo-ttgo-twatch-2020-micropython/blob/master/README.md
   * https://github.com/lvgl/lv_micropython
There is also a big collection of [[https://github.com/lvgl/lv_examples][example programs]] available for both languages.
---++ Software available for the T-Watch

The factory firmware is [[https://github.com/sharandac/My-TTGO-Watch][https://github.com/sharandac/My-TTGO-Watch. ]]This is a rather complex C++ program using LVGL and the Arduino IDE for platformio. It uses the [[https://github.com/Xinyuan-LilyGO/TTGO_TWatch_Library/tree/master/src][TTGO_TWatch_Library]] providing drivers for the T-Watch devices as well as icons and background wallpapers.
---++ Running lv_micropython of the t-watch

!MicroPython compiles for the t-watch "out of the box". In order to get a version with lvgl and all drivers and their !MicroPython language binding to work is another story. Therefore the repository mentioned above.

The !MicroPython language binding contains lvgl initialization code in the module _display_driver.py,_ which makes it very easy to create and run simple lvgl programs on the t-watch. _display_driver.py_ checks on which hardware it is running
   * SDL driver for the uniy port simulating a display
   * ili9341, used e.g. on the !LoLin TFT-2.4" display
   * or the t-watch
and performs the necessary actions like registration of the display and touch screen drivers with lvgl.

The code of a very basic example is given below together with a screen dump of what you will see on the t-watch screen.

<img alt="lvgl_bar_code.png" height="198" src="%ATTACHURL%/lvgl_bar_code.png" title="lvgl_bar_code.png" width="365" />

<img alt="lvgl_bar.png" height="279" src="%ATTACHURL%/lvgl_bar.png" title="lvgl_bar.png" width="242" />

-- %USERSIG{UliRaich - 2021-01-08}%

---++ Comments

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png	lvgl_bar.png	r1	manage	4.2 K	2021-01-08 - 11:17	UliRaich
png	lvgl_bar_code.png	r1	manage	22.0 K	2021-01-08 - 11:17	UliRaich
Topic revision: r3 - 2021-01-29 - UliRaich