mc68hc908qf4 Freescale Semiconductor, Inc, mc68hc908qf4 Datasheet - Page 98

• Manufacturer Part Number: mc68hc908qf4
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Oscillator Module (OSC)
11.8 Input/Output (I/O) Registers
11.8.1 Oscillator Status Register
Data Sheet
98
Table 11-2
source.
The oscillator module contains these two registers:
The oscillator status register (OSCSTAT) contains the bits for switching from
internal to external clock sources.
ECGON — External Clock Generator On Bit
ECGST — External Clock Status Bit
1. Oscillator status register (OSCSTAT)
2. Oscillator trim register (OSCTRIM)
Address: $0036
This read/write bit enables external clock generator, so that the switching
process can be initiated. This bit is forced low during reset. This bit is ignored in
monitor mode with the internal oscillator bypassed.
This read-only bit indicates whether or not an external clock source is engaged
to drive the system clock.
Reset:
Read:
Write:
1 = External clock generator enabled
0 = External clock generator disabled
1 = An external clock source engaged
0 = An external clock source disengaged
Freescale Semiconductor, Inc.
For More Information On This Product,
shows how the OSCOPT bits are used to select the oscillator clock
OSCOPT1
Bit 7
R
R
0
Figure 11-4. Oscillator Status Register (OSCSTAT)
0
0
1
1
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= Reserved
Oscillator Module (OSC)
R
6
0
Table 11-2. Oscillator Modes
OSCOPT0
0
1
0
1
R
5
0
Internal Oscillator
External Oscillator
External RC
External Crystal
R
4
0
= Unimplemented
Oscillator Modes
R
3
0
MC68HC908QF4 — Rev. 1.0
R
2
0
ECGON
1
0
MOTOROLA
ECGST
Bit 0
0