NXP Semiconductors K32 L2A Series, Reference Manual, Page: 850 / 1379

The IDLE status flag includes logic that prevents it from getting set repeatedly when the
LPUART_RX line remains idle for an extended period of time. IDLE is cleared by
writing 1 to the LPUART_STAT[IDLE] flag. After LPUART_STAT[IDLE] has been
cleared, it cannot become set again until the receiver has received at least one new
character and has set LPUART_STAT[RDRF].
If the associated error was detected in the received character that caused
LPUART_STAT[RDRF] to be set, the error flags - noise flag (LPUART_STAT[NF]),
framing error (LPUART_STAT[FE]), and parity error flag (LPUART_STAT[PF]) - are
set at the same time as LPUART_STAT[RDRF]. These flags are not set in overrun cases.
If LPUART_STAT[RDRF] was already set when a new character is ready to be
transferred from the receive shifter to the receive data buffer, the overrun
(LPUART_STAT[OR]) flag is set instead of the data along with any associated NF, FE,
or PF condition is lost.
If the received character matches the contents of MATCH[MA1] and/or MATCH[MA2]
then the LPUART_STAT[MA1F] and/or LPUART_STAT[MA2F] flags are set at the
same time that LPUART_STAT[RDRF] is set.
At any time, an active edge on the LPUART_RX serial data input pin causes the
LPUART_STAT[RXEDGIF] flag to set. The LPUART_STAT[RXEDGIF] flag is
cleared by writing a 1 to it. This function depends on the receiver being enabled
(LPUART_CTRL[RE] = 1).
Functional description
K32 L2A Reference Manual, Rev. 2, 01/2020
850 NXP Semiconductors