difference between arduino uno and arduino uno smd ?

Helloo world !
what is the difference between arduino uno and arduino uno smd ?
and thanks .. . . :slight_smile:

The SMD one uses the atmega328p in the SMD package (TQFP32) instead of the socketed DIP package (it was introduced when there was a major shortage of the the '328p in the DIP package; this often happens in the world of integrated circuits as manufacturers move production to a new process to lower production costs (aka "die shrink") or to a different facility for economic or logistic reasons. This wreaks havoc on smaller companies that use the parts; the larger ones have employees whose sole job is to manage sourcing of parts).

The SMD chip itself has two extra analog inputs, but the Uno SMD board doesn't break them out. So it's functionally identical, except that you can't replace the '328p if it gets damaged - in practice with official boards (and clones that use the 16u2 as serial adapter) this is rarely relevant, because the sort of abuse that would trash the (replacable on non-SMD Uno's) 328p will also trash the 16u2 (which you can't really replace without hot-air rework equipment). It does mean that you can't take the '328p out and put it on a breadboard, or remove it and use the uno as a serial adapter (though the latter practice is kind of silly anyway, since you can get serial adapters online for under $2 shipped, made with a more durable serial interface chip).