MC68HLC908QY4 Datasheet, PDF (96/182 Pages) Motorola, Inc – Microcontrollers

Oscillator Module (OSC)
11.8.2 Oscillator Trim Register (OSCTRIM)
Address: $0038
Bit 7
6
5
4
3
2
1
Read:
TRIM7
Write:
TRIM6
TRIM5
TRIM4
TRIM3
TRIM2
TRIM1
Reset: 1
0
0
0
0
0
0
Figure 11-5. Oscillator Trim Register (OSCTRIM)
Bit 0
TRIM0
0
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 approximately 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 4.0 MHz (1.0 MHz bus speed) ±25%.
MC68HLC908QY/QT Family Data Sheet, Rev. 3
96
Freescale Semiconductor