README

	For SPI display support see below.

This sample program demonstrates some features of the LVGL embedded GUI
library v9.2.2 ((c) 2021 LVGL Kft):

	https://github.com/lvgl/lvgl
	https://lvgl.io

The program can be controlled with an USB mouse, with the official Raspberry
Pi touch screen or with some USB HID-class digitizer touch screens and is
itself only a wrapper, which uses the LVGL widgets demo program.

To build the sample you have to clone the LVGL project first, which is included
as Git sub-module into Circle. To do this, just enter:

	git submodule update --init addon/lvgl/lvgl

First build the Circle libraries from Circle project root, then the LVGL library
by entering "make" in the addon/lvgl/ directory. Finally the sample can be built
with "make" in addon/lvgl/sample/.

Please note that the system generates log messages on screen, when an USB mouse
is connected, while the program is running. This destroys the displayed GUI. To
prevent this, you should add the following option to the file cmdline.txt to
direct the log output to the serial interface:

	logdev=ttyS1


This example can be used on a ST7789- or ILI9314-based SPI display or on
a SSD1306-based I2C display too. For it you have to update the configuration for
your display in the file addon/display/displayconfig.h and must enable one (!)
of the following definitions in the Makefile before build:

SPI_DISPLAY = DISPLAY_TYPE_ST7789
SPI_DISPLAY = DISPLAY_TYPE_ILI9341
I2C_DISPLAY = DISPLAY_TYPE_SSD1306

You also have to build the library in addon/display/ before build.
