System Integration Module (SIM)
Technical Data
MC68HC908AB32
—
Rev. 1.0
112
System Integration Module (SIM)
MOTOROLA
8.3 SIM Bus Clock Control and Generation
The bus clock generator provides system clock signals for the CPU and
peripherals on the MCU. The system clocks are generated from an
incoming clock, CGMOUT, as shown in
. This clock can come
from either an external oscillator or from the on-chip PLL.
See
Section 9. Clock Generator Module (CGM)
Figure 8-3. CGM Clock Signals
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$FE00
SIM Break Status Register
(SBSR)
Read:
R
R
R
R
R
R
SBSW
R
Write:
Note
Reset:
0
0
0
0
0
0
0
0
Note: Writing a logic 0 clears SBSW.
$FE01
SIM Reset Status Register
(SRSR)
Read:
POR
PIN
COP
ILOP
ILAD
0
LVI
0
Write:
POR:
1
0
0
0
0
0
0
0
$FE03
SIM Break Flag Control
Register
(SBFCR)
Read:
BCFE
R
R
R
R
R
R
R
Write:
Reset:
0
= Unimplemented
R
= Reserved
Figure 8-2. SIM I/O Register Summary
PLL
OSC1
CGMXCLK
÷
2
BUS CLOCK
GENERATORS
SIM
CGM
SIM COUNTER
MONITOR MODE
CLOCK
SELECT
CIRCUIT
CGMVCLK
BCS
÷
2
A
B S
*
CGMOUT
*
When S = 1,
CGMOUT = B
USER MODE
PTC3
Summary of Contents for MC68HC908AB32
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