Datasheet

Enhanced Serial Communications Interface (ESCI) Module
MC68HC908QB8 Data Sheet, Rev. 3
112 Freescale Semiconductor
13.3.1 Data Format
The SCI uses the standard mark/space non-return-to-zero (NRZ) format illustrated in Figure 13-3.
Figure 13-3. SCI Data Formats
13.3.2 Transmitter
Figure 13-4 shows the structure of the SCI transmitter.
Figure 13-4. ESCI Transmitter
BIT 5BIT 0 BIT 1
BIT 0 BIT 1 BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7 BIT 8
BIT 2 BIT 3 BIT 4 BIT 6 BIT 7
PARITY
OR DATA
BIT
PARITY
OR DATA
BIT
NEXT
START
BIT
NEXT
START
BIT
STOP
BIT
STOP
BIT
8-BIT DATA FORMAT
(BIT M IN SCC1 CLEAR)
9-BIT DATA FORMAT
(BIT M IN SCC1 SET)
START
BIT
START
BIT
PEN
PTY
STOP876543210START
11-BIT
TRANSMIT
T8
SCTE
SCTIE
TCIE
SBK
TC
PARITY
GENERATION
MSB
ESCI DATA REGISTER
LOAD FROM SCDR SHIFT ENABLE
PREAMBLE
(ALL ONES)
BREAK
(ALL ZEROS)
TRANSMITTER
CONTROL LOGIC
SHIFT REGISTER
TC
SCTIE
TCIE
SCTE
M
ENSCI
LOOPS
TE
TXINV
INTERNAL BUS
÷ 4
PRE-
SCALER
SCP1
SCP0
SCR1
SCR2
SCR0
BAUD
DIVIDER
÷ 16
SCI_TxD
PRE-
SCALER
PDS1
PDS2
PDS0
PSSB3
PSSB4
PSSB2
PSSB1
PSSB0
LINT
TRANSMITTER
INTERRUPT REQUEST
BUSCLKX4
OR
BUS CLOCK