user2815: So there is this pretty generic part of my project that involves triggering an ISR that will flip a boolean value. I have set up the software side like so: 
void setup() {
  attachInterrupt(digitalPinToInterrupt(2), displayConvergence, FALLING);
}

void loop() {
  if(flashConvergence) {
    //Do stuff that takes several seconds 
    delay(3000);
    flashConvergence = false;
  }
}

void displayConvergence() {
  if (!flashConvergence) {
    flashConvergence = true;
  }
}

The schematic is as follows:

simulate this circuit – Schematic created using CircuitLab
But the behavior of my circuit surprised me as the pin interrupt would get triggered randomly at a frequency at (guessing here) 3 times a second. 
Weird, I thought. I fiddled around and found that when the boost converter's 180V is not connected to any load, the interrupt service triggers as expected, as in it starts working correctly. So I thought perhaps the issue was some noise introduced by the boost converter. 
I modified the circuit by adding a capacitor across the switch: 

simulate this circuit
I tried 1 uF at first, but that didn't help and neither did 10 uF. However, when I tried 100 uF (I thought decoupling capacitors are usually 0.1uF to 1 uF, is the value I am using too big?), things seem to be working as expected with the exception that when I hold the switch in the closed position for a long time, then let it go back in the open position, the interrupt service can be triggered randomly for a short period right after I let go of the switch. 
Is my initial assumption that the ISR is triggering randomly due to EMI from the boost converter correct? Perhaps there are other causes I am not looking at? Is there a way to make this work 100% (as in solve the issue right after the switch is put in the open position)? 
Thanks for the help!

user2815: It has come to my attention I never posted a followup to this but I was actually able to solve this problem by shielding the wire going from the switch to the arduino. The switch's wire was about 2 to 3 inches long and I wrapped aluminum foil around it, which shielded the signal from what I suspected was EMI induced by the switching converters.


2815: <p>So there is this pretty generic part of my project that involves triggering an ISR that will flip a boolean value. I have set up the software side like so: </p>

<pre class="lang-c prettyprint-override"><code>void setup() {
  attachInterrupt(digitalPinToInterrupt(2), displayConvergence, FALLING);
}

void loop() {
  if(flashConvergence) {
    //Do stuff that takes several seconds 
    delay(3000);
    flashConvergence = false;
  }
}

void displayConvergence() {
  if (!flashConvergence) {
    flashConvergence = true;
  }
}
</code></pre>

<p>The schematic is as follows:</p>



<p><img src="https://i.stack.imgur.com/ZE3pg.png" alt="schematic"></p>



<p><sup><a href="/plugins/schematics?image=http%3a%2f%2fi.stack.imgur.com%2fZE3pg.png">simulate this circuit</a> &ndash; Schematic created using <a href="https://www.circuitlab.com/" rel="nofollow">CircuitLab</a></sup></p>

<p>But the behavior of my circuit surprised me as the pin interrupt would get triggered randomly at a frequency at (guessing here) 3 times a second. </p>

<p>Weird, I thought. I fiddled around and found that when the boost converter's 180V is not connected to any load, the interrupt service triggers as expected, as in it starts working correctly. So I thought perhaps the issue was some noise introduced by the boost converter. </p>

<p>I modified the circuit by adding a capacitor across the switch: </p>



<p><img src="https://i.stack.imgur.com/adfpO.png" alt="schematic"></p>



<p><sup><a href="/plugins/schematics?image=http%3a%2f%2fi.stack.imgur.com%2fadfpO.png">simulate this circuit</a></sup></p>

<p>I tried 1 uF at first, but that didn't help and neither did 10 uF. However, when I tried 100 uF (I thought decoupling capacitors are usually 0.1uF to 1 uF, is the value I am using too big?), things seem to be working as expected with the exception that when I hold the switch in the closed position for a long time, then let it go back in the open position, the interrupt service can be triggered randomly for a short period right after I let go of the switch. </p>

<p>Is my initial assumption that the ISR is triggering randomly due to EMI from the boost converter correct? Perhaps there are other causes I am not looking at? Is there a way to make this work 100% (as in solve the issue right after the switch is put in the open position)? </p>

<p>Thanks for the help!</p>
 2815: <p>It has come to my attention I never posted a followup to this but I was actually able to solve this problem by shielding the wire going from the switch to the arduino. The switch's wire was about 2 to 3 inches long and I wrapped aluminum foil around it, which shielded the signal from what I suspected was EMI induced by the switching converters.</p>

<p><a href="https://i.stack.imgur.com/MWI5S.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/MWI5S.png" alt="Poor Man&#39;s EMI Shielding"></a></p>
