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Functional description
As long as C2[SBK] is set, the transmitter logic continuously loads break characters into
the transmit shift register. After the software clears C2[SBK], the shift register finishes
transmitting the last break character and then transmits at least one logic 1. The automatic
logic 1 at the end of a break character guarantees the recognition of the start bit of the
next character.
When queuing a break character, it will be transmitted
following the completion of the data value currently being
shifted out from the shift register. This means that, if data is
queued in the data buffer to be transmitted, the break character
preempts that queued data. The queued data is then transmitted
after the break character is complete.
46.5.1.5 Idle characters
An idle character contains all logic 1s and has no start, stop, or parity bit. Idle character
length depends on C1[M], C1[PE], BDH[SBNS] and C4[M10]. The preamble is a
synchronizing idle character that begins the first transmission initiated after setting
C2[TE].
If C2[TE] is cleared during a transmission, the transmit data output signal becomes idle
after completion of the transmission in progress. Clearing and then setting C2[TE] during
a transmission queues an idle character to be sent after the dataword currently being
transmitted.
When queuing an idle character, the idle character will be
transmitted following the completion of the data value currently
being shifted out from the shift register. This means that if data
is queued in the data buffer to be transmitted, the idle character
preempts that queued data. The queued data is then transmitted
after the idle character is complete.
If C2[TE] is cleared and the transmission is completed, the
UART is not the master of the TXD pin.
1298
NOTE
Note
KV4x Reference Manual, Rev. 2, 02/2015
Preliminary
Freescale Semiconductor, Inc.
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