02 Display and Touch

GM-3568JHF development board is designed based on Rockchip RK3568J chip, providing rich display interfaces and supporting multiple display output methods. The development board is equipped with mainstream display interfaces such as HDMI and MIPI DSI, which can meet the display needs of different application scenarios.

1 Display Interface Overview

1.1 Supported Display Interfaces

Interface Type	Quantity	Max Resolution	Features
HDMI	1	4K@60Hz	Standard Type-A interface, supports hot plug
MIPI DSI	1	1920×1080	Low power consumption, suitable for embedded display
eDP	1	2560×1600@60Hz	High performance embedded display interface

1.2 Display Controller Features

GPU: ARM G52 2EE, supports OpenGL ES 1.1/2.0/3.2, OpenCL 2.0, Vulkan 1.1
2D Acceleration: Embedded high-performance 2D acceleration hardware
Multi-display Output: Supports simultaneous output to multiple display devices
Color Support: Supports RGB 4:4:4 color format
Hardware Acceleration: Supports video decoding and graphics rendering hardware acceleration

2 MIPI DSI Interface

2.1 MIPI DSI Technology Introduction

MIPI DSI (Display Serial Interface) is a display interface standard designed specifically for mobile devices by the MIPI Alliance, with the following characteristics:

Low Power Design: Optimized for mobile and embedded devices
High Integration: Reduces PCB routing complexity
Strong Anti-interference Ability: Differential signal transmission, anti-EMI interference
Flexible Configuration: Supports 1-4 data lanes configuration

2.2 Hardware Connection

MIPI_DSI

Connect the MIPI display screen to the MIPI interface of the development board via FPC cable as shown in the figure. Ensure that the power supply and signal lines of the display screen are connected correctly.

2.3 MIPI Screen Display Test

After the development board is powered on, you can see the following interface on the MIPI screen.

MIPI_DSI_2

2.4 Backlight Test

Execute the following command to change the screen brightness by modifying the brightness level.

root@linaro-alip:/# echo 1 > /sys/class/backlight/backlight/brightness
root@linaro-alip:/# echo 255 > /sys/class/backlight/backlight/brightness

3 HDMI Interface

3.1 HDMI Technology Introduction

HDMI (High Definition Multimedia Interface) is a high-definition multimedia interface, which is a purely digital audio and video transmission interface that can transmit audio and video data simultaneously through a single cable.

3.2 HDMI Interface Type

The development board uses a standard HDMI Type-A interface, with pin definitions as follows:

Pin	Signal Name	Description
1	TMDS Data2+	TMDS Data Channel 2 Positive
2	TMDS Data2 Shield	TMDS Data Channel 2 Shield
3	TMDS Data2-	TMDS Data Channel 2 Negative
4	TMDS Data1+	TMDS Data Channel 1 Positive
5	TMDS Data1 Shield	TMDS Data Channel 1 Shield
6	TMDS Data1-	TMDS Data Channel 1 Negative
7	TMDS Data0+	TMDS Data Channel 0 Positive
8	TMDS Data0 Shield	TMDS Data Channel 0 Shield
9	TMDS Data0-	TMDS Data Channel 0 Negative
10	TMDS Clock+	TMDS Clock Positive
11	TMDS Clock Shield	TMDS Clock Shield
12	TMDS Clock-	TMDS Clock Negative
13	CEC	Consumer Electronics Control
14	Reserved	Reserved
15	SCL	I2C Clock Line
16	SDA	I2C Data Line
17	DDC/CEC Ground	DDC/CEC Ground
18	+5V Power	+5V Power
19	Hot Plug Detect	Hot Plug Detect

The HDMI interface of the development board is standard HDMI, supporting hot plug and adaptive resolution.

3.3 Desktop Resolution Switching

Open System Settings and find Display

HDMI

Click Resolution to switch between different resolutions

HDMI_2

3.4 Switching Resolution via Command Line

Use xrandr -q parameter to view the resolutions currently supported by your screen

root@linaro-alip:/# xrandr -q
Screen 0: minimum 320 x 200, current 2640 x 1280, maximum 16384 x 16384
HDMI-1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 527mm x 296mm
   1920x1080     60.00*+  74.97    50.00    59.94
   1680x1050     59.88
   1600x900      60.00
   1280x1024     75.02    60.02
   1440x900      59.90
   1280x800      59.91
   1152x864      75.00
   1280x720      60.00    50.00    59.94
   1024x768      75.03    70.07    60.00
   832x624       74.55
   800x600       72.19    75.00    60.32    56.25
   720x576       50.00
   720x480       60.00    59.94
   640x480       75.00    72.81    66.67    60.00    59.94
   720x400       70.08

Use xrandr -s 0 command to restore the screen to its original resolution
Use xrandr -s to specify the screen resolution size

For example:

xrandr -s 1280x800

4 eDP Interface

4.1 eDP Technology Introduction

eDP (Embedded DisplayPort) is a digital display interface standard designed for internal connections, developed by the Video Electronics Standards Association (VESA). eDP is an optimized version of the DisplayPort standard for embedded applications, mainly used for connecting the motherboard to the built-in display in devices such as laptops, tablets, and all-in-one PCs.

4.2 RK3568J eDP Controller Features

eDP Version: Supports eDP 1.3 standard
Max Resolution: 2560×1600@60Hz
Data Lanes: Supports up to 4 physical lanes
Color Depth: Supports up to 10-bit color depth
Link Rate: Supports 1.62Gbps, 2.7Gbps, 5.4Gbps
Audio Support: Supports audio data transmission
Adaptive: Supports link training and adaptive adjustment

4.3 eDP Interface Composition

The eDP interface mainly contains the following signals:

Signal Name	Description
Main-Link	Main link, used for transmitting video/audio data
TX0+/TX0-	Data Lane 0 differential signal pair
TX1+/TX1-	Data Lane 1 differential signal pair
TX2+/TX2-	Data Lane 2 differential signal pair
TX3+/TX3-	Data Lane 3 differential signal pair
AUX+/AUX-	Auxiliary channel, used for transmitting configuration commands
HPD	Hot Plug Detect signal

5 Touch Screen

There is a set of I2C TP interfaces on the development board, and the default touch IC driver is gt911.

The connection is shown in the figure below:

Swipe or tap the screen to test if it works properly.