LCD Display Usage
The RDK X3 Module carrier board provides one MIPI DSI interface, supporting the connection of various LCD screens. The following example uses a 4.3-inch MIPI LCD to illustrate the screen connection and usage.
The screen connection is as shown in the following diagram:
It is strictly prohibited to plug or unplug the screen when the development board is not powered off, as it may cause short circuits and damage to the screen module.
Since the RDK X3 Module system defaults to HDMI output, it needs to be switched to LCD display mode through commands. First, execute the following command to back up the DTB:
sudo cp /boot/hobot/hobot-x3-cm.dtb /boot/hobot/hobot-x3-cm_backup.dtb
Execute the following command to determine the current display type:
sudo fdtget /boot/hobot/hobot-x3-cm.dtb /chosen bootargs
Taking HDMI as an example, executing the above command will print:
sunrise@ubuntu:~$ sudo fdtget /boot/hobot/hobot-x3-cm.dtb /chosen bootargs
earlycon loglevel=8 kgdboc=ttyS0 video=hobot:x3sdb-hdmi
Execute the following command to modify the chosen node:
sudo fdtput -t s /boot/hobot/hobot-x3-cm.dtb /chosen bootargs "earlycon loglevel=8 kgdboc=ttyS0 video=hobot:cm480p"
Execute the following command to print the modified node and confirm that the modification was successful:
sudo fdtget /boot/hobot/hobot-x3-cm.dtb /chosen bootargs
Enter the following command to restart the development board:
sync
sudo reboot
The display mode has been switched from HDMI to DSI.
If you want to switch back to HDMI display, after entering the kernel, execute the following command:
sudo cp /boot/hobot/hobot-x3-cm_backup.dtb /boot/hobot/hobot-x3-cm.dtb
sync
Then enter sudo reboot to restart the development board.