Recently S32K144 LPURAT function, the tests on the development board has the RX grounding, can receive a frame from LPUART DATA value is 0 (set breakpoints found LPUART initialization program run time can be received immediately after RDRF marks, and the DATA value is 0), I found in the reference manual S32K LPUART receiving the first bit of detection:

That is to receive the conditions of the start bit is falling edge need a (a serial port is not?) ,
Have Daniel to help analyze the?