Description
If your program will perform SPI transactions within an interrupt, call this function to register the interrupt number or name with the SPI library. This allows SPI.beginTransaction() to prevent usage conflicts. Note that the interrupt specified in the call to usingInterrupt() will be disabled on a call to beginTransaction() and re-enabled in endTransaction().
Syntax
SPI.usingInterrupt(interruptNumber)
Parameters
interruptNumber: the associated interrupt number.
Returns
None.