What is your interrupt source.? Does that pin has a pullup or pull down resistor.
Add a small value ceramic capasitor between an interrupt pin and ground.
Set all unconnected pins as output high.
Add a ferrite bed between power converter and arduino.
The interrupt source is a photo electric sensor. I do have a 1K pullup resistor on that line which seemed to improve the issue but not completely resolve it. Also have a small ceramic cap on there. Do you have any recommendations for the ferrite bead?
You did not show the important parts, like the relay. How is your relay powered, dd you add diodes to the relay coil and contacts?
I have put a diode at the relay and it does resolve the issue, but it isn’t practical in practice because this will be going in some of our vehicles and we can’t suppress every relay. I was excited that this did help, but hard to implement. Was hoping to get something in my device that could resolve the ripple.
Did you build this circuit, or did you buy a module?
If you built it, is it on a PCB with a ground plane?
Does the relay have a Back EMF suppression diode fitted across its coil?
I built this circuit on a PCB which does have a ground plane. Same answer to Dr. regarding the suppression diode.
Thank you all for your help! Would putting an inductor/choke on the VIN help suppress? Should I just poll the pin for changes rather then go the interrupt route? Maximum velocity is 4800 pulses per minute.