Display and Touch

The GM-3568JHF development board is designed based on the Rockchip RK3568J chip and provides rich display interfaces, 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 requirements of different application scenarios.

1 Display Interface Overview

1.1 Supported Display Interfaces

Interface Type	Quantity	Maximum Resolution	Features
HDMI	1	4K@60Hz	Standard Type-A interface, supports hot-plug
MIPI DSI	1	1920×1080	Low power consumption, suitable for embedded displays
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: Built-in 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 hardware acceleration for video decoding and graphics rendering

2 MIPI DSI Interface

2.1 MIPI DSI Technology Introduction

MIPI DSI (Display Serial Interface) is a display interface standard developed by the MIPI Alliance specifically for mobile devices, 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, resistant to EMI interference
Flexible Configuration: Supports 1-4 data lane configurations

2.2 Hardware Connection

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

2.3 MIPI Screen Display Test

Power on the development board, and you will see the following interface on the MIPI screen.

MIPI_DSI_2

2.4 Backlight Test

Run 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, a purely digital audio/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 the pin definitions as follows:

Pin	Signal Name	Function Description
1	TMDS Data2+	TMDS data channel 2 positive signal
2	TMDS Data2 Shield	TMDS data channel 2 shield
3	TMDS Data2-	TMDS data channel 2 negative signal
4	TMDS Data1+	TMDS data channel 1 positive signal
5	TMDS Data1 Shield	TMDS data channel 1 shield
6	TMDS Data1-	TMDS data channel 1 negative signal
7	TMDS Data0+	TMDS data channel 0 positive signal
8	TMDS Data0 Shield	TMDS data channel 0 shield
9	TMDS Data0-	TMDS data channel 0 negative signal
10	TMDS Clock+	TMDS clock positive signal
11	TMDS Clock Shield	TMDS clock shield
12	TMDS Clock-	TMDS clock negative signal
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 line
18	+5V Power	+5V power supply
19	Hot Plug Detect	Hot-plug detection

The HDMI interface of the development board is a standard HDMI, hot-pluggable with adaptive resolution

3.3 Switching Resolution on the Desktop

Open System Settings and find Display

HDMI

Click Resolution to switch between different resolutions

HDMI_2

3.4 Switching Resolutions via Command Line

Use the 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 the xrandr -s 0 command to restore the screen to its original resolution
xrandr -s specifies 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 specifically for internal connections, developed by the Video Electronics Standards Association (VESA). eDP is an embedded-optimized version of the DisplayPort standard, mainly used for the connection between the mainboard and built-in display in devices such as laptops, tablets, and all-in-one computers.

4.2 RK3568J eDP Controller Features

eDP Version: Supports eDP 1.3 standard
Maximum 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 includes the following signals:

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

5 Touchscreen

There is a group 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 whether it works properly