Another Millis Timer off question...

Projects Programming
18

Although I am a fan of state machines using switch/case the requirement here is easily met using very simple logic.

const byte welderPin = 13;
const byte gasPin = 12;
const byte buttonPin = A3;
byte currentButtonState = HIGH;
byte previousButtonState = HIGH;
unsigned long currentTime;
unsigned long postFlowStartTime;
unsigned long postFlowPeriod = 5000;
boolean postFlowInProgress = false;

void setup()
{
  Serial.begin(115200);
  digitalWrite(welderPin, HIGH);
  digitalWrite(gasPin, HIGH);
  pinMode(gasPin, OUTPUT);
  pinMode(welderPin, OUTPUT);
  pinMode(buttonPin, INPUT_PULLUP);
  digitalWrite(welderPin, HIGH);
  digitalWrite(gasPin, HIGH);
}

void loop()
{
  currentTime = millis();
  previousButtonState = currentButtonState;
  currentButtonState = digitalRead(buttonPin);
  if (currentButtonState != previousButtonState)
  {
    if (currentButtonState == LOW) //button became pressed
    {
      digitalWrite(welderPin, LOW); //turn on the welder
      digitalWrite(gasPin, LOW); //turn on the gas
      postFlowInProgress = false;  //allow for welder restart during post flow period
    }
    else    //button became released
    {
      digitalWrite(welderPin, HIGH);   //turn off the welder
      postFlowStartTime = currentTime;
      postFlowInProgress = true;
    }
  }
  if (postFlowInProgress)
  {
    if (currentTime - postFlowStartTime >= postFlowPeriod)
    {
      digitalWrite(gasPin, HIGH); //turn off the gas
      postFlowInProgress = false;
    }
  }
}