I am using an Arduino Due for a project. I am running out of digital pins, using 22 to 53. Can pins 0 to 13 and SCL1, SDA1 be used as digital inputs?

How about analog pins (A0 to A11) and DACs?


2 Answers 2


Bear in mind that this has nothing to do with "Electrical Engineering". This simply is an arduino question. And should be asked on arduino Stack Exchange.


They can be used as input/output pins. [Simple 'tutorial'] If that even isn't enough or not working on your type of arduino, you can use I/O expanders or shift registers. Check them out on the internet. [I/O expanders]


Yes, sort of. All the Analogs/digitals can be used as digital outputs with the following exceptions. TX0/RX0 (unless you are aware of what you're doing), SPI buss (SCK/MOSI/MISO), SDA1/SCL1, & CANRX/CANTX. DAC0/DAC1 may be used but be aware the min/max those two pins can output is ~0.55 to 2.75V.

And these exclusions are only for an arduino DUE. Other Arduino's will have more/less exclusions.

Correction: I was able to use CANRX and CANTX as alias pin names to declare these two lines as digital outputs, and set the pin values high/low in the normal way.

  • With the min/max of ~0.55 tot 2.75V, do you mean that those outputs can't be 0V? Or that ~0.55v is at least required tot read a logic high?
    – aaa
    Mar 29, 2017 at 9:03
  • That's what the Datasheet stated for those two pins, my guess is that the DAC outputs are part of an internal R2R DAC network so Vss and Vdd may not be achievable on those two pins. Jun 4, 2017 at 20:07

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