Auto Boot from SD?



Hi All,

I’ve been experimenting with different SD card images and something I don’t understand…probably completely simple…it seems any OpenROV images or stock BBB images on an SD Card will boot from the SD card automatically, without holding down the S2 button during power on. I’ve tried this after disconnecting power completely. I’m pretty sure this is the case (my SD card has files on it that do not exist on the emmc). I also see the blue LED representing SD card access going wild, nothing on the blue emmc LED.

If I load up, say, an Ubuntu Beaglebone image, the TI SDK image…I can only get the SD card to boot when holding down the switch.

The load in emmc for me right now is the stock BBB image.

Do the OpenROV/Stock SD Card images really manage to cause a boot from the SD card? The common thread between the two is Debian.

Any insight as to how this works or confirmation that I’m crazy and this can’t really happen is appreciated.



Hi lenny_m_baker,
You might want to have a look at this, which setups SD card to flash the eMMc on powerup. The line to be commented out for the uEnv.txt file in OpenROV image would be:


Haven’t tried it myself yet. Let me know it it works.


Hi @muqaddas_jamil ,

Thanks for the info. At this time I’m not looking to flash the emmc, at least not yet. I’m trying to straighten out what I see at boot. Everything I’ve read suggests the beaglebone black will never boot from the SD card when there is a valid MLO and uboot in the emmc boot partition unless the S2 switch is held during power on.

What I see is anytime a Debian based SD card is inserted, it seems the BBB boots from the SD without holding the switch. Other SD cards (I have one with Ubuntu and another with Agaro from the TI SDK) will only boot if I hold down S2.

Do you have any info on that? Ultimately, I’d like to boot from the SD card without using the switch regardless of distribution on the image, though I want a valid MLO and uboot on the emmc as a backup to the SD card.

I realize I wasn’t very clear about what I was looking for in my initial post, sorry about that!

Thanks for your reply,