38.9.1.2 RX FIFO Status Flags

There are three receive status flags:
  • RFFIF (TFERFFIF): Receive FIFO Full Interrupt Flag; set when the FIFO is full.
  • RFHIF (TFHRFHIF): Receive FIFO Half Full Interrupt Flag; set when the FIFO is at least half full.
  • RFNIF (TFNRFNIF): Receive FIFO Not Empty Interrupt Flag; set when there is at least one message in the FIFO.

The status flags of the receive FIFO are set when there are received messages in the FIFO. Before the first message is received (after the FIFO is reset), all status flags are cleared. When the FIFO is full, all flags are set.