I have a question I see the drawing you have shows a 50:1 coming from the plasma cutter voltage divider. What if your plasma cutter has a 1:1 output how do you suggest wiring to the thc. Would you still install the cap?

 

I am building the THC controller and have hit a snag with the screen I have the screen you have stated and uploaded the gui file from the site, but I keep getting the same error message on the screen "File Version is Too low" I am not so good on Gui and I am stuck I have tried different SD cards but still get the same error

 

Jeramiah, in one of your posts in this forum topic, you stated that if anyone could integrate your THC into a GRBL machine, you would like to know how they did it. Well, I have done it...
You can check out the new source code (with due credit to you, of course!) at my GitHub fork of your repository.

Basically, I re-wrote your code into an ISR -- the program monitors the ARC-OK signal and, when received, triggers an interrupt to assume control of the Z-axis during the cut. When not actively cutting, the program simply passes the Z-axis pulses on to the stepper motor driver from the GRBL controller un-altered.

I also changed the plasma voltage mapping you used (to accomodate Everlast's 0-3 volt arc voltage range) to map(analogRead(PLASMA_INPUT_PIN) + CalibrationOffset, 0, 1023, 0, 16500), so now it works on the Everlast 62i/ 82i/102i cutters without having to resort to full arc voltage and a home-brew voltage divider.

In the process of re-writing your code, I fixed many minor coding issues that kept the Nextion display from being updated and -- as a side result -- kept values from being stored in the EEPROM. Nextion has changed a lot of their firmware, and I believe that they simply changed the methods you used to pass values to the display; the EEPROM issues were caused by a conflict between data types.

I changed the EEPROM address allocation routine to use pointers to assign and pass the EEPROM addresses instead of the values themselves, then passed that pointer to other functions (EEPROM.readInt(*addressPage1) instead of EEPROM.readInt(addressPage1); this saved on memory usage, too.

As for the Nextion functions, most of them require that values passed to them be cast to uint32_t instead of just passing the native int value -- once I cast them properly, and put the serial initialization code into the "Splash Screen" pre-initialize event code (you forgot to in the HMI file in your repository), the display functioned properly and showed/ stored data as it should.

As I said, the THC works well now -- with only one issue that I am trying to figure out. At the very end of the cut, when the THC is passing control back to GRBL, it seems to want to dive into the metal -- I believe that it relates to your code block

Code:

  //after cut reset height
  pos = 0;
  //do move
  stepper.moveTo(pos);
  while (stepper.distanceToGo() != 0) {
    stepper.run();
  }

at the end of the height following routine. I saw no initialization of the torch height by the THC at the start of the interrupt, so I believe that it simply doesn't know where to reset the height to when it finishes.

Here is a short video of this THC in action, attached to this post. I've also attached a wiring diagram for an entire Mega 2560-based GRBL machine, complete with limit switches & this THC.