Is faster really more problematic?

BebopALot

Folks I am writing code to generate on/off signals at 12.5us on/ 12.5us off. Is it more reliable to write and execute such a program at 50MHz rather than 75MHz? Does the SX get really hot at 75MHz and possibly miss critical commands? I would prefer to keep mine at 75MHz, but if that produces too much heat and a zero compare is missed in decsz command then my accuracy goes haywire. Would it be beneficial to check an overflow bit every now and then or run it more slowly? Or are these concerns more theoretical than anything?

Thank you, B.

Bean

You are probably experiencing the dreaded "read/modify/write" problem.
Basically when you set an I/O pin it may not read back that state for a cycle to two at very fast clock rates.

Bean.

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Nate

I would run the SX as slow as possible that allows you to keep up with all inputs and outputs.··Slower=less power and EMI issues.· If the 12.5us signal is the most·demanding part of your program (I am assuming it is not, as you are asking about using 50/75 MHz clocks), I would even consider droping down to a 4 MHz clock.

Nate

Post Edited (Nate) : 2/1/2006 10:00:30 AM GMT

BebopALot

Thanks Nate and Bean, that makes a lot of sense. I guess too much power and speed can mess you up a bit. Thank you.

LoopyByteloose

If you really need or want the 75Mhz, go with 3.3volt power. Less headaches for the speedy.

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