Auto boot from sd card whitout pressing boot key

[amirhg]

Hi.
I have bought a core6818 board. (core one not the smart one).
The problem is the board always boots from EMMC unless I press the boot key button at the startup.
The point is I want a hardware/software solution to change boot priority and make sd card the first boot option.
I have tried this solution but with no success:

1. remove EMMC portions. (No success)
2. Trying to change npi-config -> boot option. (Only support allwinner chips)

The current state is like this: I plug the power and the board tries to boot from emmc but fails because there is no OS in emmc and the os is on the SD-card. it boots from sdcard when I press the boot button physically but I need to boot from an sd-card without pressing it.
Thanks in advance

[Stephen21]

Hey there,

Removing the eMMC partitions won't work because the board's hardware (bootROM) doesn't care about partitions. It looks for a bootloader in the raw sectors at the very beginning of the eMMC. Because the bootloader is still there, the board tries to boot from it, fails, and gets stuck.

To make it automatically fall back to the SD card without needing the physical button, you have to completely wipe that bootloader off the eMMC.
nullsbrawl
Here is the easy software fix:

Boot into your SD card OS (you'll have to press the boot button this one last time).

Open a terminal.

Zero out the first few megabytes of the eMMC using the dd command.

It will look something like this:

Code: Select all

sudo dd if=/dev/zero of=/dev/mmcblkX bs=1M count=10

(Note: Be sure to replace mmcblkX with your actual eMMC drive name, which is usually mmcblk0 or mmcblk1.)

Once those first 10 megabytes are wiped blank, the board will see that the eMMC is completely empty and will automatically skip straight to the SD card every time you plug it in.