Continuous SPI for multiple bytes

Official Hardware Mega Due
17

My next step is to remind myself how to do direct port manipulation for the CS LOW/HIGH, as there is a long delay before / after the actual transfer before the CS pin flips.
IIRC should be something like PORTD = PORTD & 0b00100000 ....

There is a digitalWriteDirect function (from another thread) that I think is about 9X faster...

// example: digitalWriteDirect(10, HIGH)
inline void digitalWriteDirect(int pin, boolean val){
  if(val) g_APinDescription[pin].pPort -> PIO_SODR = g_APinDescription[pin].ulPin;
  else    g_APinDescription[pin].pPort -> PIO_CODR = g_APinDescription[pin].ulPin;
}