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Topic: RFI with standalone atmega328 (Read 827 times) previous topic - next topic

gtr_stitch

So, weird things are going on. I out together a standalone arduino for my simple home security system. Didn't feel like having my board hooked up to it all the time. Anyways, when I was using the board, I had no problems whatsoever. But now with a standalone unit, there seems to be some very strange interference. It was running, and I went to the kitchen to make dinner. I have a gas stove with one of those automatic igniters. When it was igniting the flame, I notice my arduino alarm kept going off. I checked this over and over, and everytime the igniter sparked, the alarm went off. I know the voltage that runs those sparks is high, so I thought maybe some weird rfi or emp. That's not where the weird stops. Whenever the microwave door is shut, the same thing happens...
Anyone have any idea wth is going on?? Kinda freaked out here...

gtr_stitch

I should specify...whenever the microwave door is closed, it sets it off. Even weirder, I have an LCD display to show if there is motion outside or if someone opens a door downstairs. Whenever one of these weird occurrences...occur...the display doesn't show anything. The piezo speaker is the only thing that goes off.

oric_dan

Do you have long unshielded wires connecting everything in the house?

Grumpy_Mike

Yes this is not weird it is perfectly normal. Impulse interference is caused by sparks, the door switch sounds like it is arcking.
The cure is, supprise surprise, more decoupling on power supplies, and surge suppression on long leads.

gtr_stitch

Ahh I see. I do have a pretty lengthy cat5 cable connecting the reed switch and pir to the arduino. Maybe adding a capacitor to that length of wire could suppress any surge? Its bundled up and maybe has some kind of inductance going on which could pick up the impulse. As far as power source....i have the standalone set connected to my arduino boards 5v output. I can still use my boards for projects and power my system until I feel like digging out a 5v regulator. What kinda still bugs me is that the LCD doesn't show what tripped. But the piezo is part of an interrupt so I can have that sound and blink an indicator led, so maybe the impulse is short enough to trigger the interrupt but not long enough for it to register on

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