Arduino Forum

Products => Arduino Due => Topic started by: nedgonaes on Dec 24, 2015, 05:48 am

Title: How many digital pins can I drive with Arduino DUE?
Post by: nedgonaes on Dec 24, 2015, 05:48 am
I'm testing a chip that our lab built, and I need to drive a lot of IO pins (I think I need at least 55 pins).

I wanted to use an Arduino Due to drive these IO pins, but I'm not sure which pins I can actually use as digital IO pins.  So I'm looking at the sweet pin diagram (http://www.robgray.com/temp/Due-pinout.pdf) that shows all of the many names for every pin on the Arduino due.  If I count the number of pins that have a digital pin number in grey next to them, I get 72 potential pins.

There are a few pins that appear to be marked as "unsupported" like RXD2 and TXD2, but I'm guessing that just means the arduino libraries don't support using them as a serial port yet (but I can still use them as a digital IO).  Is that correct?

I would like to avoid using pins that are also used for other stuff, particularly the tx and rx pins that are used for programming the board, because I don't want those signals propagating to the chip I'm testing.  Are there other pins like that which I should avoid?

Do any of the other pins need to be handle specially in order to be used as a plain old digital IO pin?
Title: Re: How many digital pins can I drive with Arduino DUE?
Post by: nedgonaes on Dec 24, 2015, 06:02 am
One more question.  When I write an arduino program, which of the labels in the diagram should I use to refer to the pins?  I know there are usually macros defined for these types of things in the header files.  For example, if I want to set RXD2/SPI-CS2/D52/B.21/92 as an output, would I do pinMode(D52, output), or pinMode(92, output), or something else?

Thanks in advance to whoever can answer these questions!
Title: Re: How many digital pins can I drive with Arduino DUE?
Post by: CrossRoads on Dec 24, 2015, 06:56 am
byte pin52 = 52; // or some meaningful name

pinMode (pin52, OUTPUT);

digitalWrite (pin52, HIGH);
Title: Re: How many digital pins can I drive with Arduino DUE?
Post by: nedgonaes on Dec 24, 2015, 07:20 am
OK so basically all of the DXX, sans the D part.  Thanks.  That answers the second question.
Title: Re: How many digital pins can I drive with Arduino DUE?
Post by: nedgonaes on Dec 27, 2015, 04:46 am
Can anyone else answer the other questions?
Title: Re: How many digital pins can I drive with Arduino DUE?
Post by: CrossRoads on Dec 27, 2015, 05:29 am
If they're brought out to a header pin you can use them as digital IO. Probably avoid D0, D1 for the serial port.

Read the uC datasheet
http://www.atmel.com/Images/Atmel-11057-32-bit-Cortex-M3-Microcontroller-SAM3X-SAM3A_Datasheet.pdf (http://www.atmel.com/Images/Atmel-11057-32-bit-Cortex-M3-Microcontroller-SAM3X-SAM3A_Datasheet.pdf)
to confirm if the analog inputs or DAC outputs support digital IO also.

Or just try them, as digital 54-70, see if code will compile, and try them with a scope, a meter, or an LED/resistor.