T-DeckLoader/lib/lvgl/docs/get-started/platforms/arduino.md

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Arduino

The LVGL library is directly available as Arduino libraries.

Note that you need to choose a board powerful enough to run LVGL and your GUI. See the requirements of LVGL.

For example ESP32 is a good candidate to create UI's with LVGL.

Get the LVGL Arduino library

LVGL can be installed via the Arduino IDE Library Manager or as a .ZIP library.

You can Download the latest version of LVGL from GitHub and simply copy it to Arduino's library folder.

Set up drivers

To get started it's recommended to use TFT_eSPI library as a TFT driver to simplify testing. To make it work, setup TFT_eSPI according to your TFT display type via editing either

• User_Setup.h
• or by selecting a configuration in the User_Setup_Select.h

Both files are located in TFT_eSPI library's folder.

Configure LVGL

LVGL has its own configuration file called lv_conf.h. When LVGL is installed, follow these configuration steps:

1. Go to the directory of the installed Arduino libraries
2. Go to lvgl and copy lv_conf_template.h as lv_conf.h into the Arduino Libraries directory next to the lvgl library folder.
3. Open lv_conf.h and change the first #if 0 to #if 1 to enable the content of the file
4. Set the color depth of you display in LV_COLOR_DEPTH
5. Set LV_TICK_CUSTOM 1

Finally the layout with lv_conf.h should look like this:

arduino
 |-libraries
   |-lvgl
   |-other_lib_1
   |-other_lib_2
   |-lv_conf.h

Initialize and run LVGL

Take a look at LVGL_Arduino.ino to see how to initialize LVGL. TFT_eSPI is used as the display driver.

In the INO file you can see how to register a display and a touchpad for LVGL and call an example.

Use the examples and demos

Note that, there is no dedicated INO file for every example. Instead, you can load an example by calling an lv_example_... function. For example lv_example_btn_1().

IMPORTANT Due to some the limitations of Arduino's build system you need to copy lvgl/examples to lvgl/src/examples. Similarly for the demos lvgl/demos to lvgl/src/demos.

Debugging and logging

LVGL can display debug information in case of trouble. In the LVGL_Arduino.ino example there is a my_print method, which sends this debug information to the serial interface. To enable this feature you have to edit the lv_conf.h file and enable logging in the section log settings:

/*Log settings*/
#define USE_LV_LOG      1   /*Enable/disable the log module*/
#if LV_USE_LOG
/* How important log should be added:
 * LV_LOG_LEVEL_TRACE       A lot of logs to give detailed information
 * LV_LOG_LEVEL_INFO        Log important events
 * LV_LOG_LEVEL_WARN        Log if something unwanted happened but didn't cause a problem
 * LV_LOG_LEVEL_ERROR       Only critical issue, when the system may fail
 * LV_LOG_LEVEL_NONE        Do not log anything
 */
#  define LV_LOG_LEVEL    LV_LOG_LEVEL_WARN

After enabling the log module and setting LV_LOG_LEVEL accordingly, the output log is sent to the Serial port @ 115200 bps.