The IOREF pin is there for letting shields know what voltage the IO pins are expecting.
It could also be used a voltage source (it is the output of a voltage regulator); on the Mega it is tied to 5V on the header pin with a 16mil wide trace.
The IOREF pin is there for letting shields know what voltage the IO pins are expecting.
It could also be used a voltage source (it is the output of a voltage regulator); on the Mega it is tied to 5V on the header pin with a 16mil wide trace.