CLK question

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Hi,
I am working with a DSP and an atmega16 and was wondering if I could use one of the GPIO pins of the DSP along with one of its timers to clock the atmega16? and if so are there any disadvantages to doing this? Thanks in advance.

-X

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There shouldn't be any problems. It might make debugging and fault-finding harder.

Leon

Leon Heller G1HSM

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No problem, but keep a test point there so you can check with a scope whether the DSP is actually sending a clock to the AVR or not.

Using a clock derived from one device on another device has several advantages, the big one being the synchronous nature of the clocks, so you don't have to bother with stuff like clock detection and jitter.

The downside, like Leon said, is that if the DSP is having problems generating the clock, the AVR won't work either, so it can't tell you what's happening (I'm assuming the AVR is there for UI and control).

If you think education is expensive, try ignorance.

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I'd say that you'd want to have the master control the AVR's /RESET as well. Although AVRs claim "fully static operation", I have no idea what would happen if, say, the master was reset and the AVR's clock "paused" for some period of time. There are the warnings in the datasheets about changing clock speed more than a fraction of a percent at a time.

Lee

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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Paused clock shouldn't matter as long as reset is held asserted until the DSP is ready to go... I would put a pulldown resistor on the AVR's reset line and have the DSP push it high only once it's ready to go...

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thanks very much for the input,it is much appreciated. Will let you know how it works out.

-X