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Altera_Forum
Honored Contributor
Honored ContributorVarible clock rate
Hello together I have a verilog-module that is working with an external 25 MHz clock. Now in my application I would like to work with a variable clock rate. Some other logic modules in the FPG...
Altera_ForumHonored Contributor
Honored ContributorHi Geri,
for whatever rate value you choose, the final rate will tend to be correct over time despite the irregular nature of enable. This is a matter of accum. resolution and design toloerances but 32 bits is pretty high for most. You can if you wish use a dedicated accum for a given ratio e.g. for 20MHz on 25MHz you have two choices: generic high resolution accum: modulo 2 above then: 20 = 25 * incr/2^32 then incr = 2^32 * 20/25 = 2^32 * 0.80000... option 2: dedicated accum: i.e. incr = 20, accum 0~24 or incr = 4, accum = 0~4 (in effect a divider)
