MC68HC711PH8 Motorola, MC68HC711PH8 Datasheet - Page 119

• Manufacturer Part Number: MC68HC711PH8
• Description: High-density Complementary Metal Oxide Semiconductor (HCMOS) Microcomputer Unit
• Manufacturer: Motorola

6.6.2
The contents of this register determine the clock rate for MI BUS.
S2B[12:0] — SCI baud rate/ MI BUS clock rate selects
Use the following formula to calculate MI BUS clock rate. Refer to the table of baud rate control
values (see Table 5-1) for example rates:
where the baud rate control value (BR) is the contents of S2BDH/L (BR = 1, 2, 3,... 8191).
The clock rate generator is disabled if BR = 0, or if neither the receiver nor transmitter is enabled
(both RE and TE in SCCR2 are cleared).
Writes to the baud rate registers will only be successful if the last (or only) byte written is SCBDL.
The use of an STD instruction is recommended as it guarantees that the bytes are written in the
correct order.
Note:
6.6.3
WOMS2 — Wired-OR mode for MI BUS pins (PG0, PG1)
MIE2 — Motorola interface bus enable 2
When MIE2 is set, the SCI2 registers, bits and pins assume the functionality required for MI BUS.
MC68HC11PH8
SCI2/MI baud high (S2BDH)
SCI2/MI baud low (S2BDL)
SCI2/MI control 1 (S2CR1)
1 (set)
0 (clear) –
1 (set)
0 (clear) –
ST4XCK may be the output of the PLL circuit or it may be the EXTAL input of the MCU.
Selection is made by the MCS bit in the PLLCR (see Section 2.5).
S2BDH, S2BDL — MI BUS clock rate control registers
S2CR1 — MI BUS control register 1
–
–
TXD2 and RXD2 are open drains if operating as outputs.
TXD2 and RXD2 operate normally.
MI BUS is enabled for this subsystem.
The SCI functions normally.
MOTOROLA INTERCONNECT BUS (MI BUS)
Address
Address
$0050 B2TST B2SPL B2RST S2B12 S2B11 S2B10 S2B9
$0051
$0052
MI BUS clock rate
S2B7
bit 7
bit 7
Ñ
WOMS2 MIE2
S2B6
bit 6
bit 6
S2B5
bit 5
=
bit 5
---------------------------- -
16
ST 4 XCK
S2B4
bit 4
bit 4
Ñ
2 BR
S2B3
bit 3
bit 3
Ñ
S2B2
bit 2
bit 2
Ñ
S2B1
bit 1
bit 1
Ñ
S2B8 0000 0000
S2B0 0000 0100
bit 0
bit 0
PT2
MOTOROLA
0000 0000
on reset
on reset
State
State
TPG
6-9
6