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Topic: timing and decoupling (Read 1 time) previous topic - next topic

fungus


hey thanks for all the replies. ok so i fixed the timing...but i don't understand why it works. basically the startup time changed by 2 seconds after I put in the decoupling capacitors.


Only the startup? It's fine after that?
No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

dhenry

Quote
everything seems to be running very smoothly now. here is a terrible fritzing of my circuit


Sounds like your "running very smoothly" isn't exactly smooth, :)

Low temperature will greatly impact the oscillator (internal rc or crystal) but that's in matters of ms, not seconds.

treebykooba

hey thanks for all the replies. ok so i fixed the timing...but i don't understand why it works. basically the startup time changed by 2 seconds after I put in the decoupling capacitors. in the startup() i had a delay of 5500 to allow a digital video frame to boot up....now i changed that 5500 to 3500 and everything is rock solid.

but i'm timing this all based on how the atmega circuit is in sync with a digital video frame. it's very cold in my studio now...could the cold have anything to do with startup time? maybe it was the video frame that started up faster and the arduino was actually the same the whole time? unlikely i know....but just thought i'd ask. anyway...everything seems to be running very smoothly now. here is a terrible fritzing of my circuit...i still haven't got down the schematics view section of fritzing:

http://www.jeremycouillard.com/circuit2.jpg

2 of the .1 caps next to the motors are actually soldered onto the body of the motor. i got that idea from here: http://www.pololu.com/docs/0J15/9

pwillard

Time to *show* us what you really did with a picture or schematic I think.

fungus


So my question is...will the off timing be consistent? So I can just adjust the code accordingly? My loop probably takes about half a second longer now or so it seems. Or would it be less predictable? I assume it's because of the 47uf cap on the power rails...it's taking a bit of time to charge/decharge.


It's not supposed to charge/discharge under normal use.

If it is charging/discharging then it's either not in the right place for a decoupling capacitor or your power supply isn't supplying enough current for whatever it is you're building.

No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

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