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12435 Discussions

how to choose clock frequency for nios components

Altera_Forum
Honored Contributor II
835 Views

Dear All, 

I'm here to ask for a fundamental. When I add a component in a NIOS system often have doubts about the right clock to connect to. I mean, there are some modules that provide outputs to drive external device(jtag uart, lcd, epcs devices....etc). Devices requires correct timing at least in terms of maximum switching speed. 

I understand that is not realistic to have always all the components in the system clocked with the same clock, so for example clock crossing bridges are povided. But I wuold like to know wich is the correct clock frequency for modules. I mean, where to find the informations about clock selection for jtag uart or epcs controller?  

Thanks a lot in advance.
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4 Replies
Altera_Forum
Honored Contributor II
96 Views

Hi, 

It depends on the components to use. 

It's always simpler to have all of them on the same clock, unless you're obliged to do otherwise: 

- need pll clock compensation for different parts of a big design. 

- have camera or VGA or other that already have a different clock. 

- need different performance and power savings strategies on different components 

that's as far as I know, and I guess the list can be completed...
Altera_Forum
Honored Contributor II
96 Views

thank WASS, 

I was actually asking information on how to find informations about NIOS components clock requirments.
Altera_Forum
Honored Contributor II
96 Views

Did you took a look at the Embedded Peripherals IP user guide : 

http://www.altera.com/literature/ug/ug_embedded_ip.pdf 

You'll find details for every peripheral, you can "ctl+f" the word "clock", or fully read the peripheral you're interested in.
Altera_Forum
Honored Contributor II
96 Views

:) but not the clock details... 

let's do the case of the Optrex16207 LCD controller core. I don't see any reference to the component clock selection.
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