Are there additional digital I/O pins on top of the Arduino Nano?

Using Arduino Project Guidance
1

I was looking at the Arduino Nano pinout and notice the header pins on the top appear to have a few digital I/O pins? Is this true or am I misreading it?

My project uses every I/O already :o A couple more would be useful...

2

That's the ICSP header, which is normally used for connecting an ISP programmer. You can see the pinout here:

In fact some of the pins on the header are I/O pins but they are duplicates of the pins already broken out along the edge of the Nano so there are no extras. For more information, see:

3

It doesn't appear I can use this as a digitalRead? My current project uses every digital and analog pin of the nano. I'd love a couple, more. Hmm.

4

I already explained this. You can use the pins marked MOSI, MISO, or SCK in the image above as I/O pins but they are not extra pins, they are pins 11, 12, and 13, which are already broken out along the edge of the Nano, and I take you're already using.

There are options for adding more I/O pins. Which is best depends on your application. For adding extra digital input pins check out this tutorial:

Another common chip for that application is SN74HC165.

5

Hi,

You're already using A6 and A7 that are not available on the UNO, right??

6

Oops, you're right. I zoned out. Thank you for the advice.

7

A6 & A7 are analog input only, so read & test for >= 6/10 * 1024 for a high, and <= 3/10 * 1024 for a low.
Values in between would be indeterminate digital levels.

8

CrossRoads:
A6 & A7 are analog input only, so read & test for >= 6/10 * 1024 for a high, and <= 3/10 * 1024 for a low.
Values in between would be indeterminate digital levels.

Note that this is substantially slower than digitalRead(). Would probably be better to move any other analogRead activity to those two pins, reclaiming the digitalRead capable A0~5 pins.

9

It sounds like it's time to upgrade to a Teensy 3.6 then. Unfortunately all Teensy 3.x models are 3.3V, although the Teensy 3.5 is 5V tolerant. (It will take 5V as an input but will only output 3.3V and analog inputs only go 0-3.3V.)

On a Micro, there's some "hidden" output pins at the TX LED and RX LED. digitalWrite(TXLED, HIGH) will turn the LED on.

10

Or a mega (Or "mega mini" ) Or 1284p based board if you want to stay in avr land.