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?
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.
FYI... often overlooked, A4 and A5 on the Pro Mini are actually right above A3 and A2.
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.
And while you're at it connect to AREF (chip pin 20) too...
But Aref is not any good for an analog or digital IO pin?
MarkT: 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.
Whatcha mean Lefty? Pin 20 on the TQFP is Aref, on the promini just has a cap to ground.
CrossRoads: 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!) ???
No it can't, however the AREF pin can be useful - and the Mini Pro annoyingly doesn't bring it out to a pad...
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).