README

This sample demonstrates using the character driver for ST7789-based dot-matrix displays.
You have to set your hardware configuration in the file kernel.cpp before build.
The DC_PIN is required, the RESET_PIN and BACKLIGHT_PIN are optional and not
provided by some displays. Please specify the GPIO chip number (not the header
position) here or CST7789Display::None, if the pin is not connected.

This relies on the st7789 display driver to function.

The default display connection is as follows:

Display		Raspberry Pi	Comment
			GPIO

SCL	<--	SCLK	11	SPI clock
SDA	<--	MOSI	10	SPI data
CS		not used	Chip select, e.g. GPIO8 (CS0) or GPIO7 (CS1)
DC	<--		22	Data/Command selection
RES	<--		23	Reset
BLK		not used	Backlight, e.g. GPIO24
VCC	<--	3.3V		may be 5V for some displays (be careful!)
GND	<-->	GND

An additional DOUT line is not used, if provided by the display. In the given
configuration the SPI settings CPOL/CPHA are normally 1/0. If a chip select line
is provided by your display, this may change to CPOL/CPHA 0/0. You can try this
out, if the display does not work.

There are two modes of the demo program. If you start it without an USB keyboard
connected, it will display "No keyboard!" on the LCD display and will count the
time from program start on.

With an USB keyboard connected you can type on it and the typed characters will
be echoed to the LCD display. You may have to set-up your keyboard map first,
using the "keymap=" setting in cmdline.txt (see doc/cmdline.txt) to get
reasonable results here.
