MIPI Screen Detection Demo

Demo overview

This demo shows how to test the MIPI interface on the development board.

The board's backlight control device node is /sys/class/backlight/backlight. Run the following command to change the screen brightness according to the value.

echo 200 | sudo tee /sys/class/backlight/backlight/brightness

This demo controls the brightness by writing different brightness values to the backlight control device node.

Hardware connection

Before testing, make sure the MIPI display is correctly connected to the board. The connection diagram is below.

Procedure

Copy the executable smdt_lcd_demo from this demo's bin directory (05-Development Materials\Software Development Materials\linux_demo\smdt_lcd_demo\bin) to the board's filesystem (the source code is available under the src path). Open a terminal and run the following command to switch to the directory containing the smdt_lcd_demo executable.

cd ‘文件所在目录’

After switching, run ls to confirm that smdt_lcd_demo is in the current directory.

ls

If the executable smdt_lcd_demo is present in the current directory, continue. Run the following command to change the file's permissions.

chmod 777 smdt_lcd_demo

After changing the permissions, run the following command to verify the change.

ls -ld smdt_lcd_demo

The result should be: -rwxrwxrwx 1 root root 19016 Mar 3 09:55 smdt_lcd_demo.

-rwxrwxrwx indicates the permission change succeeded and the file is executable; you may continue.

Continue by running the following command to view the program's parameter information.

./lcd_demo -h
./lcd_demo -d /sys/class/backlight/backlight/

The MIPI screen backlight brightness cycles from high to low, holding each brightness level for 0.5s. The command window prints the following information:

Press Ctrl+C to exit the test.