Comment out some of the main programs debug print statements plus add yield call to main loop.

yield can now call SerialEvent.

Put hack in that if the user has not overwritten the SerialEvent function, the weak linked one will turn off calling itself...

Update pins 30 and 31 in core_pins.h

The B2 board has different IO pins here for these two pins

while(1); -> while (1) asm ("WFI");

Saves power and prevents heating

undocumented SNVS regs

use GPIO6..9

add SNVS definitions for RTC

add #define digitalPinToInterrupt(p)

todo:
analogInputToDigitalPin(p)
digitalPinHasPWM(p)

Add SD Cards as IO pins - plus fix Serial2 and Serial8 for T4 B2

Fixed the Serial2 object to use the new correct pins, plus made Serial8 only valid for T4 B1 (not B2).

Also I defined IO pins for the six signals associated with the SD Card slot.

I have tested these both as IO pins and now as SPI2

update setpad in Analog.c and added debug info in startup

Fix SPDF Base-Address

Startup: save RAM with .progmem

T4 Imxrt define Flexio structure.

Moved from my flexio_t4 library.
Libary was updated to see if already defined before it now defines it.

clock halved - halve blink wait count