Boot pins have unexpected behaviour

Dear all,
According to the schematics of BeagleBone Black, If I don’t press S2 button, the boot will start with internal eMMC (MMC1), then external SD card (MMC0).

When I connect external SD card, and (not pressing S2), the boot starts from the external SD card!

Am I making something wrong ?


2 parts… We have the bootrom, and “u-boot”…

bootrom, depending on usr button, will either load “u-boot” from eMMC or microSD…

Next, “u-boot” on the eMMC will scan the microSD first, before trying the eMMC…


Thanks Robert,

I’ve tried it and could prove it.

I think this is managed by uEnv.txt in the eMMC.

The question is: How does the SPL know: from where to get the uboot to load in the DDR ?

SPL should grab it from the same interface.