ST7789 display connected to a nRF5340DK board

[lcj]

I am trying to test a nRF5340 with a 1.3 inch waveshare 240x240 display using a st7789 driver. How would I connect the display to the board:

VCC	3.3v
GND	Ground
DIN	Serial Data
CLK	Serial Clock
CS	Chip Select
DC	Data Command/Control
RST	Reset
BL	Backlight

and create an overlay file representing the display connections?

[WesC]

The ST7789 has many node specific properties outside the SPI interface

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/build/dts/api/bindings/display/sitronix,st7789v.html#std-dtcompatible-sitronix-st7789v

you can look at the Pinetime devkit0 with the DTS for a reference.  there is a node specific to the ST7789 and it is part of the chosen node as zephyr,display.  you can mimic that in an overlay.  you can find the dts here C:\ncs\v2.4.2\zephyr\boards\arm\pinetime_devkit0

[lcj]

So create an overlay file for the board and copy the st7789, correct? Where do I connect the wires from the display to the 5340dk?

I see these two display settings in the pinetime dts and the shield. They are both under a spi, is there some way I should set this up for the nrf5340dk?

&arduino_spi { status = "okay"; cs-gpios = <&arduino_header 16 GPIO_ACTIVE_LOW>;        /* D10 */   st7789v_st7789v_waveshare_240x240: st7789v@0 { compatible = "sitronix,st7789v"; spi-max-frequency = <20000000>; reg = <0>; cmd-data-gpios = <&arduino_header 15 GPIO_ACTIVE_LOW>;        /* D9 */ reset-gpios = <&arduino_header 14 GPIO_ACTIVE_LOW>;        /* D8 */ width = <240>; height = <240>; x-offset = <0>; y-offset = <0>; vcom = <0x19>; gctrl = <0x35>; vrhs = <0x12>; vdvs = <0x20>; mdac = <0x00>; gamma = <0x01>; colmod = <0x05>; lcm = <0x2c>; porch-param = [0c 0c 00 33 33]; cmd2en-param = [5a 69 02 01]; pwctrl1-param = [a4 a1]; pvgam-param = [D0 04 0D 11 13 2B 3F 54 4C 18 0D 0B 1F 23]; nvgam-param = [D0 04 0C 11 13 2C 3F 44 51 2F 1F 1F 20 23]; ram-param = [00 F0]; rgb-param = [CD 08 14]; }; };

&spi1 { /* Sitronix ST7789V LCD */ st7789v: st7789v@1 { compatible = "sitronix,st7789v"; reg = <1>; spi-max-frequency = <8000000>; /* 8MHz */ cmd-data-gpios = <&gpio0 18 GPIO_ACTIVE_LOW>;        /* DET */ reset-gpios = <&gpio0 26 GPIO_ACTIVE_LOW>;        /* RESX reset */ width = <240>; height = <240>; x-offset = <0>; y-offset = <0>; vcom = <0x19>; gctrl = <0x35>; vrhs = <0x12>; vdvs = <0x20>; mdac = <0x00>; gamma = <0x01>; colmod = <0x05>; lcm = <0x2c>; porch-param = [0c 0c 00 33 33]; cmd2en-param = [5a 69 02 01]; pwctrl1-param = [a4 a1]; pvgam-param = [D0 04 0D 11 13 2B 3F 54 4C 18 0D 0B 1F 23]; nvgam-param = [D0 04 0C 11 13 2C 3F 44 51 2F 1F 1F 20 23]; ram-param = [00 F0]; rgb-param = [CD 08 14]; }; };

[WesC]

So if you want to use the shield you should be able to add the CMAKE argument in the build configuration in VSC.  so select "ADD Argument" under the extra cmake argument option.  in that field type

-DSHIELD=st7789v_tl019fqv01

this should add the shield in the build and you can see that in the build/zephyr folder with the Zephyr.dts file.

if you want to just use the overlay like above then you add the SPI features above the child node definition for the ST7789.  you will also need to define the pin_cntrl for those pins.  something like this:

&spi1 {
	compatible = "nordic,nrf-spim";
	status = "okay";
	pinctrl-0 = <&spi_master_default>;
	pinctrl-1 = <&spi_master_sleep>;
	cs-gpios = <&gpio0 11 GPIO_ACTIVE_LOW>;
	st7789v_st7789v_tl019fqv01: st7789v@0 {
	compatible = "sitronix,st7789v";
	spi-max-frequency = < 0x1312d00 >;
	reg = < 0x0 >;
	cmd-data-gpios = < &arduino_header 0xf 0x1 >;
	reset-gpios = < &arduino_header 0xe 0x1 >;
	width = < 0x140 >;
	height = < 0xaa >;
	x-offset = < 0x0 >;
	y-offset = < 0x23 >;
	vcom = < 0x2b >;
	gctrl = < 0x35 >;
	vrhs = < 0xf >;
	vdvs = < 0x20 >;
	mdac = < 0x60 >;
	gamma = < 0x1 >;
	colmod = < 0x55 >;
	lcm = < 0x2c >;
	porch-param = [ 0C 0C 00 33 33 ];
	cmd2en-param = [ 5A 69 02 01 ];
	pwctrl1-param = [ 52 A1 ];
	pvgam-param = [ D0 00 02 07 0B 1A 31 54 40 29 12 12 12 17 ];
	nvgam-param = [ D0 00 02 07 05 15 2D 44 44 1C 18 16 1C 1D ];
	ram-param = [ 00 F8 ];
	rgb-param = [ CD 08 14 ];
	};
}

&pinctrl {
	spi_master_default: spi_master_default {
		group1 {
			psels = <NRF_PSEL(SPIM_SCK, 0, 6)>,
					<NRF_PSEL(SPIM_MOSI, 0, 7)>,
					<NRF_PSEL(SPIM_MISO, 0, 25)>;
		};
	};

	spi_master_sleep: spi_master_sleep {
		group1 {
			psels = <NRF_PSEL(SPIM_SCK, 0, 6)>,
					<NRF_PSEL(SPIM_MOSI, 0, 7)>,
					<NRF_PSEL(SPIM_MISO, 0, 25)>;
			low-power-enable;
		};
	};
	};

[lcj]

How does the backlight (BL) connect to the board and where is it referenced in the overlay?

[helsing]

lcj said:

How does the backlight (BL) connect to the board and where is it referenced in the overlay?

It looks like the backlight is not refernced in the overlay.

What you could do is to choose a free pin and implement the control of this, either in your application or you could modify the driver.

I also searched the datasheet for 'backlight' and found this:

Perhaps it is possible to turn on or dim the backlight from the SPI interface?

I also noticed there is an overlay named st7789v_waveshare_240x240.overlay in the SDK. Have you tried that one?