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

fungus


yeah oddly enough the startup code was the only thing I had to adjust by 2 seconds and then everything worked better than ever. I have no idea why that is. Anyone have any ideas?


Can you try something smaller then 47uF...?

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Docedison

Why Smaller?, If anything at all a bigger cap... 100 - 470uF would be better and probably as big as is required. anything larger would serve little purpose. If you have the board wired Exactly as shown (A Star topology) then the only other thing I might suggest would be 1N4004 diodes across the motors cathode to the positive side, anode to ground. The star wiring method insures that all currents return INDIVIDUALLY to a common point so that ground current isn't "Shared" along with the noise due to "Daisy Chained" grounding. Because I am rather conservative (from painful experience) I develop all my circuitry on breadboards, a practice I've used for 40 years... All of what I design works right when I make a PCB from my final breadboard design. I use breadboards for design not so much because they are easier but because they are about the worst possible device to use for low noise high current loads... If I can make it work there I know (Again from painful experience) it will work about 99.5% of the time. Murphy is always present... And he was an Optimist.

Bob
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dhenry

Quote
Can you try something smaller then 47uF...?


Or even 4.7uf?

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Why Smaller?


We covered that in the 1st day of the class.

MarkT

The timing change suggests something different is happening at power-up-reset - the bootloader looks at the serial to check for an upload, potentially this could be affected by noise on that line, which in turn might be affected by capacitance, ground-plane, etc.

If you are using the 328p standalone it won't have anything connected to the RX pin (pin 0), so it will be floating and sensitive to the environment - try a 10k pull-up resistor from pin 0 to +5V maybe ?
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fungus


Why Smaller?, If anything at all a bigger cap... 100 - 470uF would be better and probably as big as is required. anything larger would serve little purpose.


To see if the start-up delay is proportional to the size of that capacitor.
No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

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