Hello All,
Hardware Manual B4 says that User Button to be held for both memory boot and peripheral boot . It can be read as
Peripheral boot (USB / Serial ) → Held User button , press and release reset button
Memory boot (NAND / MMC ) → Press and release reset button (User button in released state )
These statements are true. All the user button does is change to boot order. If a serial or USB device is not there and there is something in flash, it will still boot from FLASH. Otherwise if the user button is not pushed, it will boot form NAND first. This is the way to override the booting from flash when there is something programmed in it. It will also look for something in the MMC slot as well in the boot process.
More information on this can be found in the OMAP3530 Technical reference Manual
Gerald
You can also look on page 4 of the schematic for the boot sequence that is used based on wetter or not the User switch is pressed during reset.
Gerald