Oren:
If you used an 8051 type processor with a counter to measure the period of the divider output that had clocking resolution of 1 uSec (1 mHz) then the accuracy would be something like 1 part in 327.

I got that number as follows:

200 mHz / 65536 = 3052 Hz (with divider of 16 bits).

1 / 3052 Hz = 327.68 uSec period (at output of the CPLD divider).


If you increased the divider to 24 bits then your accuracy would be about 1 part in 83886 with a 1 uSec timer resolution.

Also keep in mind that the accuracy that you achieve will also be affected by how accurate the crystal that drives the 8051 is. For extreme accuracy it may be necessary to utilize a calibrated crystal that is in a temperature controlled oven.

Michael KAras