Another traffic light project

Question

I have a school project, where I'm going to make a traffic light system on a pls. I want to try it out on an Arduino first, just to get the hang of it.

To make it a little bit more advanced than I have found on the internet, I want to make the lights go in "emergency mode" if the green lights in both directions are on at the same time. It will then go into a yellow blink.

My idea is something like this:

// Yellow blinking if fault in the system or operator activates it
int killState = digitalRead(Kill);
int resState = digitalRead(Res);
if (killState == HIGH /*|| greenlights in both directions */) {
 while (resState == LOW;) { // Yellow blink as long as system is not reset
  BLINK();
 }
}

I guess I need a variable or two that tells what state the lights are in, but I'm stuck. Any good solutions out there?

Another thing is the reset button. I haven't put much effort in it, but I want it to go into the starting point.

The link to the complete script can be found here.

Answer 1

For starters, take a close look at this line:

while (resState == LOW;)

That is not the correct syntax. But the real issue is how is this while loop terminated? The value is never set again?

Cheers!

Answer 2

You could do something simple to test if both red and green are on, eg.

if (digitalRead (RED_PIN) == HIGH && digitalRead (GREEN_PIN) == HIGH)
  {
  digitalWrite (RED_PIN, LOW);  // turn off red
  digitalWrite (GREEN_PIN, LOW);  // turn off green
  while (true)
    {
    digitalWrite (YELLOW_PIN, HIGH);
    delay (500);
    digitalWrite (YELLOW_PIN, LOW);
    delay (500);
    }  // end of while
  }  // end of it

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If you have other questions please post your code and not a snippet - however I suggest you try to get further on your own. This is obviously an exercise, and the more you try to work it out yourself the more you will learn.