Atmel SAM R21 Xplained Pro port

SAMR21 BSP Code Review
@mathivanane,
The philosophy  for ports has been that different boards implement the exact same interface. This allows a person to switch boards (or run a heterogeneous network) without having to worry about capabilities having changed. I hope this makes sense.
In that context, I would like to suggest to "map" the existing 6 debugpins ({{frame}}, {{slot}}, {{fsm}}, {{task}}, {{isr}}, {{radio}}) to the hardware pins present on the board. If the hardware doesn't have 6 pins available, you can "sacrifice" some pins by stubbing out the corresponding debugpins.
I would hence suggest to remove the changes surrounded by the {{ifdef}}.
Thomas