ARM IM-AD1 - Manual (Page 55)

Reference Design Example
ARM DUI 0163B Copyright © 2001-2003. All rights reserved. 4-9
4.2.1 Oscillator divisor registers
The oscillator registers control the frequency of the clocks generated by the two clock
generators on the logic module.
Before writing to the oscillator registers, you must unlock them by writing the value
0x0000A05F to the LM_LOCK register. After writing the oscillator register, relock them
by writing any value other than 0x0000A05F to the LM_LOCK register.
The reference divider (R[6:0]) and VCO divider (V[8:0]) are used to calculate the
output frequency as follows:
Table 4-5 on page 4-10 describes the oscillator register bits.
Note
You can calculate values for the clock control signals using the ICS525 calculator on
the Integrated Circuit Systems web site at:
http://www.icst.com/
Frequency = 48MHz ·
(V[8:0] +8)
(R[6:0] +2) · OD