I'm trying to execute and interrupt based I2C and SPI transfer on a kl27z MCU. Examples from the SDK points to the use of SPI/I2C_MasterTransferNonBlocking with a callback function to indicate transfer is finished. However I couldn't quite understand how TransferNonBlockin works and when the interrupt is triggered. Can anyone enlighten me? Also, I would like to know the correct way of setting up FIFO in SPI1 as it is not stated anywhere in the examples.