MC68HC908GZ8 Datasheet, PDF (257/344 Pages) Motorola, Inc – Microcontrollers

Freescale Semiconductor, Inc.
System Integration Module (SIM)
SIM Bus Clock Control and Generation
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$FE00
SIM Break Status ^Read:
R
Register (SBSR) Write:
R
R
R
R
SBSW
R
Note⁽¹⁾
R
See page 271. _Reset:
0
0
0
0
0
0
0
0
1. Writing a logic 0 clears SBSW.
$FE01
SIM Reset Status ^{Read: POR}
PIN
COP
ILOP
ILAD MODRST LVI
0
Register (SRSR) Write:
See page 272. _POR:
1
0
0
0
0
0
0
0
SIM Break Flag Control Reg- ^Read: _BCFE
R
R
R
R
R
R
R
$FE03
ister (SBFCR) Write:
See page 273. _Reset:
0
$FE04
Interrupt Status ^{Read: IF6}
IF5
IF4
IF3
IF2
IF1
0
0
Register 1 (INT1) Write: R
R
R
R
R
R
R
R
See page 267. _Reset:
0
0
0
0
0
0
0
0
$FE05
Interrupt Status ^{Read: IF14}
IF13
IF12
IF11
IF10
IF9
IF8
IF7
Register 2 (INT2) Write: R
R
R
R
R
R
R
R
See page 267. _Reset:
0
0
0
0
0
0
0
0
$FE06
Interrupt Status ^Read:
0
Register 3 (INT3) Write: R
See page 267. _Reset:
0
0
IF20
IF19
IF18
IF17
IF16
IF15
R
R
R
R
R
R
R
0
0
0
0
0
0
0
= Unimplemented
R = Reserved
Figure 20-2. SIM I/O Register Summary
20.2 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 Figure 20-3. This clock originates from either an external oscillator or
from the on-chip PLL.
20.2.1 Bus Timing
In user mode, the internal bus frequency is either the crystal oscillator output
(CGMXCLK) divided by four or the PLL output (CGMVCLK) divided by four.
20.2.2 Clock Startup from POR or LVI Reset
When the power-on reset module or the low-voltage inhibit module generates a
reset, the clocks to the CPU and peripherals are inactive and held in an inactive
phase until after the 4096 CGMXCLK cycle POR timeout has completed. The RST
pin is driven low by the SIM during this entire period. The IBUS clocks start upon
completion of the timeout.
MC68HC908GZ8
MOTOROLA
System Integration Module (SIM)
For More Information On This Product,
Go to: www.freescale.com
Data Sheet
257