(LPUART_STAT[TC]) indicates that the transmitter is finished transmitting all data,
preamble, and break characters and is idle with LPUART_TX at the inactive level. This
flag is often used in systems with modems to determine when it is safe to turn off the
modem. If the transmit complete interrupt enable (LPUART_CTRL[TCIE]) bit is set, a
hardware interrupt is requested when LPUART_STAT[TC] is set. Instead of hardware
interrupts, software polling may be used to monitor the LPUART_STAT[TDRE] and
LPUART_STAT[TC] status flags if the corresponding LPUART_CTRL[TIE] or
LPUART_CTRL[TCIE] local interrupt masks are cleared.
When a program detects that the receive data register is full (LPUART_STAT[RDRF] =
1), it gets the data from the receive data register by reading LPUART_DATA. The
LPUART_STAT[RDRF] flag is cleared by reading LPUART_DATA.
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
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
1336 NXP Semiconductors
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