[SOLVED] Uno and Nano

I just want to know why the Arduino Nano has 8 Analog inputs and Arduino Uno has just 6 if they are using the same smd microcontroller (328P)? I can't understand it... :~

PS: Sorry about my bad english and grammar... ect


The Nano uses the SMD version of the chip, which has 32 pins. The Uno uses the through-hole version of the chip, which has 28 pins.

The Nano has the extra analog ports because it has the extra pins. The Uno’s chip just doesn’t have any more room.

But what about the Uno Smd? It has the same pins as the normal Uno... and the same chip that the Nano has...

But the shield headers only support 6 analog, not 8. So you only get 6 still.

On the Uno SMD schematic is looks like A6 and A7 are just left unconnected:


My guess is they wanted to keep the pins the same so all existing shields would work. Adding 2 more header pins may screw up physical compatibility.

I suppose if you were very careful you could solder leads on the ATMega chip and get those pins back, but it would be a delicate operation.

Good luck!

Thanks!! that's strange... just esthetics :| well I'll see how can i get those pins :)

Thanks for reading!


You know they are only good for analog inputs, yes?
Don’t plan on using them to supply any kind of output signal.

I broke them all out on my Mini-uino board also.

Yeah I know... it was more curiosity than anything :P Thanks for reply!!