MC68HC908LB8_05 Datasheet, PDF (130/234 Pages) Freescale Semiconductor, Inc – M68HC08 Microcontrollers

Oscillator Module (OSC)
Table 13-2. Oscillator Modes
OSCOPT1
0
0
1
1
OSCOPT0
0
1
0
1
Oscillator Modes
Internal Oscillator
External Oscillator
External RC
External Crystal
13.8 Input/Output (I/O) Registers
The oscillator module contains these two registers:
1. Oscillator status register (OSCSTAT)
2. Oscillator trim register (OSCTRIM)
13.8.1 Oscillator Status Register
The oscillator status register (OSCSTAT) contains the bits for switching from internal to external clock
sources.
Address: $0036
Bit 7
6
5
4
3
2
1
Read:
R
R
R
R
R
R
ECGON
Write:
Reset:
0
0
0
0
0
0
0
R
= Reserved
Figure 13-4. Oscillator Status Register (OSCSTAT)
Bit 0
ECGST
0
ECGON — External Clock Generator On Bit
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 when the internal oscillator is
bypassed.
1 = External clock generator enabled
0 = External clock generator disabled
MC68HC908LB8 Data Sheet, Rev. 1
130
Freescale Semiconductor