MC908AP32CFBE Datasheet, PDF (158/324 Pages) Freescale Semiconductor, Inc – The following revision history table summarizes changes contained in this document. For your convenience, the page number designators have been linked to the appropriate location.

Serial Communications Interface Module (SCI)
11.4.1 Data Format
The SCI uses the standard non-return-to-zero mark/space data format illustrated in Figure 11-3.
8-BIT DATA FORMAT
BIT M IN SCC1 CLEAR
PARITY
BIT
NEXT
START
START
BIT BIT 0 BIT 1 BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7 ^STOP BIT
BIT
START
9-BIT DATA FORMAT
BIT M IN SCC1 SET
PARITY
BIT
NEXT
START
BIT BIT 0 BIT 1 BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7 BIT 8 STOP BIT
BIT
Figure 11-3. SCI Data Formats
11.4.2 Transmitter
Figure 11-4 shows the structure of the SCI transmitter.
The baud rate clock source for the SCI can be selected via the configuration bit, SCIBDSRC. Source
selection values are shown in Figure 11-4.
INTERNAL BUS
÷4
PRE- BAUD
SCALER DIVIDER
÷ 16
SCI DATA REGISTER
SCIBDSRC
FROM
CONFIG2
CGMXCLK
BUS CLOCK
A
B
SL
X
SL = 0 => X = A
SL = 1 => X = B
SCP1
SCP0
SCR1
SCR2
SCR0
11-BIT
TRANSMIT
SHIFT REGISTER
H876543210L
TxD
TXINV
M
PEN
PARITY
PTY
GENERATION
T8
DMATE
DMATE
SCTIE
SCTE
DMATE
SCTE
SCTIE
TC
TCIE
SCTE
SCTIE
TC
TCIE
Figure 11-4. SCI Transmitter
TRANSMITTER
CONTROL LOGIC
SBK
LOOPS
ENSCI
TE
MC68HC908AP Family Data Sheet, Rev. 4
158
Freescale Semiconductor