usingInterrupt

If you program will perform SPI transaction 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(). SPI.usingInterrupt(interruptNumber)
interruptNumber: the associated interrupt number None