I'm duplicating much of the MKRZERO schematic on my own custom board. I want to be able to select the MKRZERO board from the board list in the Arduino IDE so that I don't have to make my own board file (I don't even know how to do that). On the MKRZERO headers, there are only 8 digital IO pins D0 thru D7. I noticed on the schematic that there are a couple of unused microcontroller pins that are tied to test points. My project happens to need more than just the 8 dio pins given on the headers. How do I access unused pins on the SAMD21G processor via the Arduino IDE?
Also, I posted this in another topic but got no responses: how do I determine the mapping for pin numbering in Arduino to pin numbering on the microcontroller? For example, to use SPI I have to define the clock as pin 12 (as labelled on the MKRZERO header), but this is actually port A bit 17, which is microcontroller pin 26. I assume there's some header file or something that maps the micro pins to the header pins, but where can I find that? I feel like that information would lend itself to the question above about accessing unused pins on the micro.