Chapter 20 Serial Communication Interface (S12SCIV5)
MC9S12XE-Family Reference Manual Rev. 1.19
Freescale Semiconductor
733
20.3.2.7
SCI Status Register 1 (SCISR1)
The SCISR1 and SCISR2 registers provides inputs to the MCU for generation of SCI interrupts. Also,
these registers can be polled by the MCU to check the status of these bits. The flag-clearing procedures
require that the status register be read followed by a read or write to the SCI data register.It is permissible
to execute other instructions between the two steps as long as it does not compromise the handling of I/O,
but the order of operations is important for flag clearing.
Read: Anytime
Write: Has no meaning or effect
1
RWU
Receiver Wakeup Bit
— Standby state
0 Normal operation.
1 RWU enables the wakeup function and inhibits further receiver interrupt requests. Normally, hardware wakes
the receiver by automatically clearing RWU.
0
SBK
Send Break Bit
— Toggling SBK sends one break character (10 or 11 logic 0s, respectively 13 or 14 logics 0s
if BRK13 is set). Toggling implies clearing the SBK bit before the break character has finished transmitting. As
long as SBK is set, the transmitter continues to send complete break characters (10 or 11 bits, respectively 13
or 14 bits).
0 No break characters
1 Transmit break characters
Module Base + 0x0004
7
6
5
4
3
2
1
0
R
TDRE
TC
RDRF
IDLE
OR
NF
FE
PF
W
Reset
1
1
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 20-10. SCI Status Register 1 (SCISR1)
Table 20-10. SCICR2 Field Descriptions (continued)
Field
Description
Because
of
an
order
from
the
United
States
International
Trade
Commission,
BGA-packaged
product
lines
and
part
numbers
indicated
here
currently
are
not
available
from
Freescale
for
import
or
sale
in
the
United
States
prior
to
September
2010:
S12XE
products
in
208
MAPBGA
packages
