Freescale Semiconductor, Inc.
Serial Communications Interface (SCI)
5.10 Additional SCI subsystems
In addition to the subsystem described in the above paragraphs (SCI1),
the MC68HC11P2 has two other, similar, SCI modules (SCI2, SCI3).
These two systems are identical to that described, with the following
exceptions:
SCI2 and SCI3 share I/O with four port H pins:
Alternate
function
Pin
PH4
PH5
PH6
PH7
RXD2
TXD2
RXD3
TXD3
The SCI2 transmit and receive functions are enabled by TE2 and RE2
respectively, in S2CR2; similarly, the SCI3 transmit and receive
functions are enabled by TE3 and RE3 respectively, in S3CR2.
SCI1 functions and data are handled by a register block at
$0070–$0077. The corresponding registers for SCI2 and SCI3 are at
addresses $0050–$0057 and $005A–$005F respectively, as shown in
the following sections.
SCI2 and SCI3 share the same baud rate register (at $0050/51).
In addition to their SCI functions, these two subsystems are also used
for MI BUS, controlled by bit 5 of their respective SCCR1 registers. Refer
to Motorola Interconnect Bus (MI BUS) for full details of MI BUS
operation.
5.10.1 SCI2
SCI2 shares I/O with two of port H’s pins: receive pin RXD2/PH6 and
transmit pin TXD2/PD7. The SCI receive and transmit functions are
enabled by RE and TE respectively, in S2CR2.
Technical Data
MC68HC11P2 — Rev 1.0
Serial Communications Interface (SCI)
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