45.6.6.6 TXRDY and RXRDY Behavior

TWIHS_SR.TXRDY/RXRDY flags display a specific behavior when FIFOs are enabled.

TXRDY indicates if a data can be written in the Transmit FIFO. Thus the TXRDY flag is set as long as the Transmit FIFO can accept new data. See figure TXRDY Behavior when TXRDYM = 0 in Host Mode.

RXRDY indicates if an unread data is present in the Receive FIFO. Thus the RXRDY flag is set as soon as one unread data is in the Receive FIFO. Refer to figure RXRDY Behavior when RXRDYM = 0 in Host and Client Modes.

TXRDY and RXRDY behavior can be modified using the TXRDYM and RXRDYM fields in the TWI FIFO Mode register (TWIHS_FMR) to reduce the number of accesses to TWIHS_THR/RHR.

As an example, in Host mode, the Transmit FIFO can be loaded with multiple data in the same access by configuring TXRDYM>0.

See TWI FIFO Mode register for the FIFO configuration.