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Topic: RFI with standalone atmega328 (Read 828 times) previous topic - next topic


You're kind of in the universe now where you need an oscilloscope to look at what
is actually going on. The truth is it's not easy to track down the real culprits via
guesswork alone. There are multiple problems your system can be having,

- long wires acting like antennas.
- high source impedances on signals, which compounds problem #1.
- really nasty spikes in environment meaning all I/O lines will have to have EMI
  filters added.
- may be necessary to try different types of EMI filters.
- noise getting onto sensors, meaning best to add filters out there.
- noise conducted in from the power mains through whatever power supply you're using.
- not enough existing filtering on your bd [eg, bypass and electrolytic caps].
- bd would work better in shielded box.
- on and on.


Both the digital cable TV boxes in my house (one in bedroom, one in living room) are sensitive to the sparking from a hand operated mechanical charcoal starter we use to light candles. One click and the TV screen freezes with random pixelation weirdness and about two seconds later all is well. The one in the living room also does that when the microwave door is closed and started. And these cable boxes are all metal encased devices made by Motorola, not some fly by night company.

RFI can be a strange animal to live with.



How are your sensors/devices hooked up? Perhaps isolating them with optoisolators as well as the extra  supply decoupling will solve that, if you can't optoisolate perhaps just getting some toiroidal cores and passing your longer wires a few times thru can limit the interference
also not sure how good of an idea but to ground your ckt ground to earth ground may suppress some interference,  just make sure that the supply you are using will not be harmed by that


RFI is my Arch Nemesis!

Over the years (with exception to my desktop PSU) I've had horrible dealings with RFI, light switches, ovens anything that arcs.

So i've been converting all things electronic that run on DC to run from DC, eg, the Modem 11dc from an AC switching adapter, well that AC was causing a small unwanted amount of noise, So i hooked it up to a 12v small lead acid battery (there's a DC > DC regulator inside the modem rated for 22volts) so now i get a cleaner Data Transfer signal, Tesla was a genius but he never stopped ONCE to think about people who work with microcontrollers and IC's lol..

There's a sound / clap sensor circuit I made years ago, everytime you clapped the mic picked up the sound using a flip flop, triggered a relay, but the relay caused a spark causing the circuit to turn off again! what a badly designed circuit! - I had to run it off a 9v battery to make it work properly.


Lol I've never had a problem with rfi, my arch nemesis is static electricity and the atleast 5 ics it has destroyed are maimed costing me alot of time

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