MC68HC908RK2 Datasheet, PDF (142/232 Pages) Motorola, Inc – Microcontroller Unit

Internal Clock Generator Module (ICG)
8.8.3 ICG Trim Register
Address: $0038
Bit 7
Read:
TRIM7
Write:
Reset: 1
6
5
4
3
2
1
TRIM6 TRIM5 TRIM4 TRIM3 TRIM2 TRIM1
0
0
0
0
0
0
Figure 8-13. ICG Trim Register (ICGTR)
Bit 0
TRIM0
0
TRIM7–TRIM0 — ICG Trim Factor Bits
These read/write bits change the size of the internal capacitor used
by the internal clock generator. By testing the frequency of the internal
clock and incrementing or decrementing this factor accordingly, the
accuracy of the internal clock can be improved to ±2 percent.
Incrementing this register by one decreases the frequency by
0.195 percent of the unadjusted value. Decrementing this register by
one increases the frequency by 0.195 percent. This register cannot
be written when the CMON bit is set. Reset sets these bits to $80,
centering the range of possible adjustment.
NOTE: It is recommended that the user preserve a copy of the contents of the
ICG trim register (ICGTR) in non-volitale memory.
Address $7FEF is reserved for an optional factory-determined ICG trim
value. Consult with a local Motorola representative for more information
and availability of this option.
Advance Information
142
Internal Clock Generator Module (ICG)
MC68HC908RK2 — Rev. 4.0
MOTOROLA