RS-232 Interrupts

andrey_g

Hello,

I wrote a simple interface for the inputs i get via RS-232 from my MCU.

In serialEvent i get the string, check the formatting, and if that's okay, i process it into a value and map to the screen.

In draw i output the received value in text form on the screen. The problem with that is that bytes incoming via RS-232 sometimes interrupt the process of erasing the text with a black box before writing another value on the screen. This results in artifacts like in the picture. How do you suggest i fix that?

void serialEvent(Serial myPort) 
{
  inString = myPort.readStringUntil('\n');
  if (inString != null) 
  {
    inString = trim(inString);

    stringSymbol = inString.substring(1, 2);
    if (stringSymbol.equals(":"))
    {
      allowTextF = true;
      sS = int(inString.substring(0, 1));

      inString = inString.substring(2);

      inByte = float(inString); 
      inByte = displayH - map(inByte, minValue[sS], maxValue[sS], 0, displayH);

      stroke(colors[sS]);
      line(xPos[sS] - 1, oldValue[sS], xPos[sS], inByte);
      oldValue[sS] = inByte;

      if (xPos[sS] >= displayW)
      { 
        background(0);
        for (int i = 0; i < nSignals; i++)
        {
          xPos[i] = 1;
        }
      }

      xPos[sS]++;
    }
    else allowTextF = false;
  }
}

void draw()
{
  stroke(0);
  fill(0);
  rect(displayW/2, displayH/2 - sS*(textAscent()+textDescent()), 100, textAscent()+textDescent());

  fill(colors[sS]);
  if (allowTextF == true)
  {
    text(inString, displayW/2, displayH/2 - sS*(textAscent()+textDescent()));
  }
}

GoToLoop

If draw() is meant to be updated based on serialEvent(), then you should just halt the former w/ noLoop();
and use redraw() & clear() inside the latter! 8-X

andrey_g

It took me a long time to get what you were suggesting, but disabling draw() altogether by putting noLoop() at the end of the setup() and then launching draw() manually with redraw() is a sound advice!