6.2.6. How to change dtb files


In some scenarios, it is required to manually change the dtb file used by the target. For example, AM437X GP EVM uses LCD display by default. But it also supports HDMI display. In order to switch from LCD display to HDMI display, user needs to set the dtb file as desired.

Specify dtb File

The dtb files are located on the target filesystem under “/boot” directory. First, identify the dtb file to be used, e.g., am437x-gp-evm-hdmi.dtb for AM437X GP EVM with HDMI display.

Then, modify “uEnv.txt” on the boot partition (“/run/media/mmcblk0p1” directory on filesystem) to specify fdtfile with the desired dtb file name.

Using AM4 as the example, the default uEnv.txt has the lines below. Follow the instructions to set fdtfile so that HDMI display can be enabled. In order to go back to LCD dispaly, unset fdtfile to use the default am437x-gp-evm.dtb.

# Uncomment the following line to enable HDMI display and disable LCD display.

After the dtb file is changed, reboot the EVM so that the new dtb file will be used for booting the EVM.