mc68hc908kx8 Freescale Semiconductor, Inc, mc68hc908kx8 Datasheet - Page 115

• Manufacturer Part Number: mc68hc908kx8
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

12.4.2 Transmitter
Figure 12-5
12.4.2.1 Character Length
The transmitter can accommodate either 8-bit or 9-bit data. The state of the M bit in SCI control register 1
(SCC1) determines character length. When transmitting 9-bit data, bit T8 in SCI control register 3 (SCC3)
is the ninth bit (bit 8).
12.4.2.2 Character Transmission
During an SCI transmission, the transmit shift register shifts a character out to the TxD pin. The SCI data
register (SCDR) is the write-only buffer between the internal data bus and the transmit shift register. To
initiate an SCI transmission:
Freescale Semiconductor
$0013
$0014
$0015
$0016
$0017
$0018
$0019
Addr.
1. Enable the SCI by writing a 1 to the enable SCI bit (ENSCI) in SCI control register 1 (SCC1).
2. Enable the transmitter by writing a 1 to the transmitter enable bit (TE) in SCI control register 2
3. Clear the SCI transmitter empty bit by first reading SCI status register 1 (SCS1) and then writing
4. Repeat step 3 for each subsequent transmission.
(SCC2).
to the SCDR.
SCI Baud Rate Register
Register Name
SCI Control Register 1
SCI Control Register 2
SCI Control Register 3
SCI Status Register 1
SCI Status Register 2
shows the structure of the SCI transmitter.
SCI Data Register
See page 125.
See page 127.
See page 129.
See page 130.
See page 132.
See page 133.
See page 133.
MC68HC908KX8 • MC68HC908KX2 • MC68HC08KX8 Data Sheet, Rev. 2.1
(SCDR)
(SCBR)
(SCC1)
(SCC2)
(SCC3)
(SCS1)
(SCS2)
Reset:
Reset:
Reset:
Reset:
Reset:
Reset:
Reset:
Read:
Read:
Read:
Read:
Read:
Read:
Read:
Write:
Write:
Write:
Write:
Write:
Write:
Write:
Figure 12-4. SCI I/O Register Summary
LOOPS
SCTIE
SCTE
Bit 7
R8
R7
T7
U
0
0
1
0
0
0
0
= Unimplemented
ENSCI
TCIE
TC
R6
T8
T6
U
6
0
0
1
0
0
0
0
SCRIE
TXINV
SCRF
SCP1
R5
T5
R
5
0
0
0
0
0
0
0
Unaffected by reset
SCP0
IDLE
ILIE
R4
T4
M
R
R
4
0
0
0
0
0
0
0
= Reserved
WAKE
ORIE
OR
TE
R3
T3
R
3
0
0
0
0
0
0
0
SCR2
NEIE
ILTY
RE
NF
R2
T2
2
0
0
0
0
0
0
0
Functional Description
U = Unaffected
SCR1
RWU
FEIE
PEN
BKF
FE
R1
T1
1
0
0
0
0
0
0
SCR0
PEIE
Bit 0
PTY
SBK
RPF
PE
R0
T0
0
0
0
0
0
0
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