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[on:]

I need as many I/O pins on the Arduiuno Mini Pro as possible. The info for this Arduino says it only has 14 Digital I/O but looking at the schemtic I see that PC0- PC5 = 6 , PD0-PD7 = 8 and PB0-PB6 = 6 I/O. This adds up to be 20 I/O. One of these has an LED on it and two are for the Rx/Tx for programming. Why does the doc say on 14 are available?

[Reply #1 on:]

6 of the pins are analog and thus not described as "digital". They can still be used as digital I/O, so yes it does essentially have 20 I/O pins. Just a matter of how they're described is all.

[Reply #2 on:]

FYI... often overlooked, A4 and A5 on the Pro Mini are actually right above A3 and A2.

[Reply #3 on:]

If you're reeeeeally careful, you can get 2 more Analog inouts (only!), A6/A7, by adding wires to  ATMega328  pins 19 & 22.

"In the TQFP and QFN/MLF package, ADC7:6 serve as analog inputs to the A/D converter.
These pins are powered from the analog supply and serve as 10-bit ADC channels."

Not sure what you'd have to do software wise to access those.

[Reply #4 on:]

And while you're at it connect to AREF (chip pin 20) too...

[Reply #5 on:]

But Aref is not any good for an analog or digital IO pin?

[Reply #6 on:]

And while you're at it connect to AREF (chip pin 20) too...

That's wrong. Unless you can show us in the datasheet where that is made possible, I can't.


Lefty

[Reply #7 on:]

Whatcha mean Lefty? Pin 20 on the TQFP is Aref, on the promini just has a cap to ground.

[Reply #8 on:]

Whatcha mean Lefty? Pin 20 on the TQFP is Aref, on the promini just has a cap to ground.

I thought I  was agreeing with your prior statement, Aref pin (on whatever package) can not be used as a general purpose I/O pin to the best of my knowlege and I did quickly check the datasheet but could be wrong. However the reset pin can be reused to use as I/O but that brings lots of arduino IDE compatiblity problems along with it.

Or maybe I'm just not paying close enough attention to the post/question (again!) ???

Lefty

[Reply #9 on:]

No it can't, however the AREF pin can be useful - and the Mini Pro annoyingly doesn't bring it out to a pad...

[Reply #10 on:]

Okay, I think we're all in sync - OP recognizes the 20 I/O lines, there is a way to add 2 more Analog Input lines, and Aref if connected also could be useful (as part of analog reads).