MC68HC11PH8 Datasheet, PDF (107/264 Pages) Motorola, Inc – High-density Complementary Metal Oxide Semiconductor (HCMOS) Microcomputer Unit

5.8
SCI2
In addition to the subsystem described in the above paragraphs (SCI1), the MC68HC11PH8 has
another, similar, SCI module (SCI2). This system is identical to SCI1, with the following
exceptions:
– SCI2 shares I/O with two port G pins:
Pin
Alternate
function
PG0
RXD2
PG1
TXD2
5
– The SCI2 transmit and receive functions are enabled by TE2 and RE2
respectively, in S2CR2.
– SCI1 functions and data are handled by a register block at $0070–$0077.
The corresponding registers for SCI2 are at addresses $0050–$0057, as
described in the following sections.
– The SCI2 baud rate register is at address $0050/51.
– In addition to the SCI functions,SCI2 is also used for MI BUS, controlled by
bit 5 of S2CR1. Refer to Section 6 for full details of MI BUS operation.
5.8.1 S2BDH, S2BDL — SCI2 baud rate control registers
SCI2/MI baud high (S2BDH)
SCI2/MI baud low (S2BDL)
Address bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1
$0050 B2TST B2SPL B2RST S2B12 S2B11 S2B10 S2B9
$0051 S2B7 S2B6 S2B5 S2B4 S2B3 S2B2 S2B1
bit 0
State
on reset
S2B8 0000 0000
S2B0 0000 0100
The contents of this register determine the baud rate for SCI2. For details of the bits and the
corresponding baud rates, see Section 5.6.1. This register also controls the MI BUS clock rate
(see Section 6).
MC68HC11PH8
SERIAL COMMUNICATIONS INTERFACE
TPG
MOTOROLA
5-15