How to boot from USB?

Hi, I want to boot from USB. However, I don’t know the addresses and procedure. Can you provide instruction how to boot from USB? I have addresses to which U-Boot, uImage, uInitrd, bluecore.audio and bpi-w2.dtb are loaded when launching from SD, but when I try to do it, I receive “Synchronization error” or something similiar and board restarts.

Greetings, Michał.

It’s a round about way to do it, but perhaps you could boot to usb from an sd card with grub?