Chapter 20 Serial Communication Interface (S12SCIV5)
MC9S12XE-Family Reference Manual Rev. 1.19
Freescale Semiconductor
737
NOTE
If the value of T8 is the same as in the previous transmission, T8 does not
have to be rewritten.The same value is transmitted until T8 is rewritten
In 8-bit data format, only SCI data register low (SCIDRL) needs to be
accessed.
When transmitting in 9-bit data format and using 8-bit write instructions,
write first to SCI data register high (SCIDRH), then SCIDRL.
20.4
Functional Description
This section provides a complete functional description of the SCI block, detailing the operation of the
design from the end user perspective in a number of subsections.
shows the structure of the SCI module. The SCI allows full duplex, asynchronous, serial
communication between the CPU and remote devices, including other CPUs. The SCI transmitter and
receiver operate independently, although they use the same baud rate generator. The CPU monitors the
status of the SCI, writes the data to be transmitted, and processes received data.
Table 20-13. SCIDRH and SCIDRL Field Descriptions
Field
Description
SCIDRH
7
R8
Received Bit 8
— R8 is the ninth data bit received when the SCI is configured for 9-bit data format (M = 1).
SCIDRH
6
T8
Transmit Bit 8
— T8 is the ninth data bit transmitted when the SCI is configured for 9-bit data format (M = 1).
SCIDRL
7:0
R[7:0]
T[7:0]
R7:R0
— Received bits seven through zero for 9-bit or 8-bit data formats
T7:T0
— Transmit bits seven through zero for 9-bit or 8-bit formats
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
