How to boot into uboot?

Good to know that there is no need of a level shifter. The setup should be safe and nothing should blow up (no voltage shared between R2 and Arduino). Am I right? Or both boards can tolerant 3.3 and 5 voltages?

Since when Arduino becomes a must for embedded development :slight_smile:

There is voltage shared on the Rx/Tx pins to actually send/receive bytes.

I cannot guarantee it is safe, I can only say it worked for me.

I can’t find anything definitive on what voltage levels this board will tolerate safely.

Which arduino do you use? Imho 1 or 2 are operating with 3v3…most (like nano,uno,mega) working with 5v and give this voltage on pins out…maybe bpi tolerates 5v signals…

@garywang can you confirm that r2-gpio and debug-uart are tolerating 5v?