BeagleBoard rev C3 failure to boot when connected to other boards

Hey all,

I’m a student at Georgia Tech who is working on an undergraduate-led satellite project. We are using the BeagleBoard-xM as our flight computer but have encountered a couple issues when booting. We have the BeagleBoard connected through header pins and standoffs to four other boards, which are powered with 1.6V through one of the expansion pins. We are booting with u-boot from a 32gb Sandisk Ultra micro SD card.

When booting with the standalone board everything works as expected, booting and running the processes we have installed. When we put it on the stack though it fails to boot giving the following error (not always, sometimes it gets lucky and boots) :

** Partition 1 not valid on device 0 **
spl_register_fat_device: fat register err - -1
spl_load_image_fat: error reading image u-boot.img, err - -1
SPL: failed to boot from all boot devices
### ERROR ### Please RESET the board ###

This only happens when it is on the stack and resetting does not fix it. As we though it may be a power issue, I patched U-Boot to run in 1-bit mode, and although it got past the error above, the boot process would hang randomly and never fully boot the kernel, with the SD card light staying on.

My guess is that this has to do with some power draw issue, but I am not sure how to diagnose and much less how to solve this problem. I was thinking of maybe booting from internal flash but the XM revisions do not have flash memory. Any thoughts or help would be much appreciated.

Thanks,
Alex Cabrera