57.9.6.6 TXRDY and RXRDY Behavior

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

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

RXRDY indicates if an unread byte is present in the Receive FIFO. Thus the RXRDY flag is set as soon as one unread byte is in the Receive FIFO. See 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 (FLEX_TWI_FMR) to reduce the number of accesses to FLEX_TWI_THR/RHR.

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

See FLEX_TWI_FMR for the FIFO configuration.