Serial Communications Interface Module (SCI)
11.3 Pin Name Conventions
The generic names of the SCI I/O pins are:
•
•
RxD (receive data)
TxD (transmit data)
SCI I/O (input/output) lines are implemented by sharing parallel I/O port pins. The full name of an SCI
input or output reflects the name of the shared port pin. Table 11-1 shows the full names and the generic
names of the SCI I/O pins. The generic pin names appear in the text of this section.
Table 11-1. Pin Name Conventions
Generic Pin Names:
Full Pin Names:
RxD
TxD
PTB3/RxD
PTB2/TxD
NOTE
When the SCI is enabled, the TxD pin is an open-drain output and requires
a pullup resistor to be connected for proper SCI operation.
Addr.
Register Name
Bit 7
LOOPS
0
6
ENSCI
0
5
TXINV
0
4
3
WAKE
0
2
ILTY
0
1
PEN
0
Bit 0
PTY
0
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
M
0
SCI Control Register 1
(SCC1)
$0013
SCTIE
TCIE
0
SCRIE
0
ILIE
0
TE
RE
0
RWU
0
SBK
0
SCI Control Register 2
(SCC2)
$0014
$0015
0
0
R8
T8
DMARE
DMATE
ORIE
NEIE
FEIE
PEIE
SCI Control Register 3
(SCC3)
U
U
0
0
0
0
0
0
SCTE
TC
SCRF
IDLE
OR
NF
FE
PE
$0016 SCI Status Register 1 (SCS1) Write:
Reset:
1
1
0
0
0
0
0
0
Read:
$0017 SCI Status Register 2 (SCS2) Write:
Reset:
BKF
RPF
0
0
0
0
0
0
0
0
Read:
R7
T7
R6
T6
R5
T5
R4
T4
R3
T3
R2
T2
R1
T1
R0
T0
SCI Data Register
(SCDR)
$0018
$0019
Write:
Reset:
Read:
Write:
Reset:
Unaffected by reset
0
0
0
0
SCP1
0
SCP0
R
0
SCR2
0
SCR1
0
SCR0
0
SCI Baud Rate Register
(SCBR)
0
= Unimplemented
R = Reserved
U = Unaffected
Figure 11-1. SCI I/O Register Summary
MC68HC908AP Family Data Sheet, Rev. 4
156
Freescale Semiconductor
FREESCALE [ Freescale ]
