Datasheet

MC68HC908QY4•MC68HC908QT4•MC68HC908QY2•MC68HC908QT2•MC68HC908QY1•MC68HC908QT1
112 Oscillator Module (OSC) MOTOROLA
Oscillator Module (OSC)
NON-DISCLOSURE AGREEMENT REQUIRED
8.9.2 Oscillator Trim Register (OSCTRIM)
TRIM7–TRIM0 — Internal Oscillator Trim Factor Bits
These read/write bits change the size of the internal capacitor 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 appoximately 0.2% of the
untrimmed period (the period for TRIM = $80). The trimmed frequency
is guaranteed not to vary by more than ±5% over the full specified
range of temperature and voltage. The reset value is $80, which sets
the frequency to 12.8 MHz (3.2 MHz bus speed) ±25%.
Address: $0038
Bit 7654321Bit 0
Read:
TRIM7 TRIM6 TRIM5 TRIM4 TRIM3 TRIM2 TRIM71 TRIM0
Write:
Reset:10000000
Figure 8-4. Oscillator Trim Register (OSCTRIM)