Datasheet

Serial Communications Interface Module (SCI)
MC68HC908AP Family Data Sheet, Rev. 4
156 Freescale Semiconductor
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.
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.
Table 11-1. Pin Name Conventions
Generic Pin Names: RxD TxD
Full Pin Names:
PTB3/RxD PTB2/TxD
Addr. Register Name Bit 7 654321Bit 0
$0013
SCI Control Register 1
(SCC1)
Read:
LOOPS ENSCI TXINV M WAKE ILTY PEN PTY
Write:
Reset:00000000
$0014
SCI Control Register 2
(SCC2)
Read:
SCTIE TCIE SCRIE ILIE TE RE RWU SBK
Write:
Reset:00000000
$0015
SCI Control Register 3
(SCC3)
Read: R8
T8 DMARE DMATE ORIE NEIE FEIE PEIE
Write:
Reset:UU000000
$0016 SCI Status Register 1 (SCS1)
Read: SCTE TC SCRF IDLE OR NF FE PE
Write:
Reset:11000000
$0017 SCI Status Register 2 (SCS2)
Read:
BKF RPF
Write:
Reset:00000000
$0018
SCI Data Register
(SCDR)
Read: R7 R6 R5 R4 R3 R2 R1 R0
Write: T7 T6 T5 T4 T3 T2 T1 T0
Reset: Unaffected by reset
$0019
SCI Baud Rate Register
(SCBR)
Read: 0 0
SCP1 SCP0 R SCR2 SCR1 SCR0
Write:
Reset:00000000
= Unimplemented
R = Reserved U = Unaffected
Figure 11-1. SCI I/O Register Summary