MC68HC908QC16_07 Datasheet, PDF (105/274 Pages) Freescale Semiconductor, Inc – Microcontrollers

Registers
ECGST — External Clock Status Bit
This read-only bit indicates whether an external clock source is engaged to drive the system clock.
1 = An external clock source engaged
0 = An external clock source disengaged
10.8.2 Oscillator Trim Register (OSCTRIM)
Read:
Write:
Reset:
Bit 7
6
5
4
3
2
1
TRIM7 TRIM6 TRIM5 TRIM4 TRIM3 TRIM2 TRIM1
1
0
0
0
0
0
0
Figure 10-5. Oscillator Trim Register (OSCTRIM)
Bit 0
TRIM0
0
TRIM7–TRIM0 — Internal Oscillator Trim Factor Bits
These read/write bits change the internal capacitance used by the internal oscillator. By measuring the
period of the internal clock and adjusting this factor accordingly, the frequency of the internal clock can
be fine tuned. Increasing (decreasing) this factor by one increases (decreases) the period by
approximately 0.2% of the untrimmed oscillator period. The oscillator period is based on the oscillator
frequency selected by the ICFS bits in OSCSC.
MC68HC908QC16 • MC68HC908QC8 • MC68HC908QC4 Data Sheet, Rev. 3
Freescale Semiconductor
105