[quote=“TomWS, post:8, topic:13792, full:true”]
Well, one problem you are going to have with that is that the pulse width of the PUL pin is between 5-8 microseconds long. There is no way you’ll capture that reliably by reading the pin. You may get a reliable interrupt when the pin changes state and be able to infer that it pulsed, but you won’t be able to read it with Arduino C code.[/quote]
I think you may be right. I haven’t given up on something like this, but decided to focus on the need to have stuff first, not the nice to have.
Apparently renovating a bathroom was needed to have, because that’s what I did in my free time the past month.
I have hooked up the Arduino to the plasma in the sketchiest way ever, just to grab some voltage measurements to see what the noise looks like so I can start piecing together a Digikey order. Turns out 18ga thermostat wire fits right into the CNC port terminals perfect!
I was expecting noise, especially without using any shieldling, but this was way worse than I expected. I had added a voltage divider outside of the machine because 16:1 could have sent 6.5v and the Arduino needs to read <5v. I thought I did the math right to get 5v max. (V+ and V- are the pins on the Everlast)
I was expecting a signal around 4v, whereas this is averaging .7v. After some more research, I had made two errors:
- My plasma was set to 50:1 ratio, not 16:1. Oops.
- The internal circuit inside the plasma is not a voltage divider, its a T Attenuator.
Since I forgot all the DiffEQ for that years ago, I used a circuit simulator. The circuit I created, would theoretically send 6mV to the Arduino. That probably explains why there are so many 0’s in my data and everything else is just noise. The ADC in the Arduino measures ~5mV/count.
So I think I need to go to 16:1 and change to something like this and try again. (A0 is the Arduino Analog in)
Just trying to see what the raw signal looks like, I plan to add filtering, shielding, etc. Hopefully I am not way off track!