57.7.9.8.7 End of Frame Condition
The USART configured in LON mode terminates the frame with a three tbit long Manchester code violation. After sending the last CRC bit, it maintains the data transitionless during three bit periods.
While receiving data, the USART configured in LON mode detects an end of frame condition after a teof transitionless Manchester code violation. The EOFS field in the USART LON Mode Register can configure teof.