Arduino Due conditional compilation constant for custom library

Question

I'm writing a custom library and it is working correctly on an Arduino Uno. However I've now got my hands on an Arduino Due and I need to define some board specific pin constants.

I know for most boards you can do this through an #ifdef directive using the IO constants defined in \\arduino-1.5.2\hardware\tools\avr\avr\include\avr\io.h. For instance:

#if defined (__AVR_ATmega128__)
    //do something specific
#endif

Does anybody know which is the correct constant to use for the Due?

Answer 1

I typically use ...

#ifndef __AVR__
// something special just for non AVR8's
// ...
#endif

Where as I believe you could also use...

#ifdef _SAM3XA_
// something special just for Due's SAM3XA
// ...
#endif

Answer 2

The _SAM3XA_ will work, but includes a lot of other Atmel ARM chips (SAM3X8C, SAM3X8H, etc.).

Something more precise would be

#if defined (__arm__) && defined (__SAM3X8E__) // Arduino Due compatible
// your Arduino Due compatible code here
#endif

(See the file sam3.h for more info.)

If you just want to target the Arduino Due (leaving out compatible boards), you can use

#if defined (_VARIANT_ARDUINO_DUE_X_)
// your Arduino Due code here
#endif

(This is defined in the Arduino Due's variant.h file.)