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When is the function delay() a delay?

colporteur 

else if (MainDepartureState == LOW && MainArrivalState == LOW) {
        if (startupMain == HIGH) {
          // pulse turnout for Main train
          digitalWrite(Main_Turnout, HIGH);
          relayDelay();//<-----1
          digitalWrite(Main_Turnout, LOW);
          if (deBug == HIGH) {
            Serial.println("The Main Turnout Activated");
          }
          // Engage Motor for Main
          motors.setSpeedB(minSpeedB);  // Start Motor for Main
          motors.forwardB();
          PowerMain = LOW;
          startupMain = LOW;
          delay(300000);//<----2
          if (deBug == HIGH) {
            Serial.println("Motor Delay Complete");
          }

According to what I have read “The delay() function allows you to pause the execution of your Arduino code for a specified period.”

Why are the delays I am using not working or the values are so extreme? How can I best accomplish a delay?

I tried using the delay() function at point <----1 in my code and it failed miserably. I wanted to activate a relay by turning it on, waiting for relay to engage (delay(2000), then turn it off. The delay(2000) two seconds didn’t work. I wrote a little relay routine that accomplish what I wanted but why did delay(2000) not give me two seconds?

I am using delay() function at <----2 in the code but the value doesn’t reflect the actual delay. I needed to generate some wait time for the motor to engage and trigger a sensor. My desire was a three second delay(3000) but the delay(300000) was a value that actually worked. That would be 300 seconds yes/no?

I'm a code resurrectionist and not an actual programmer. I will try and muddle through discussions 

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  • in reply to Gough Lui

    I plan to make some PWM pin changes to hopefully eliminate the problem. I currently use pin 12 & 13. The plan is to use pin 44 & 46

    Code for Available PWM frequency for D44, D45 & D46:

    TCCR5B = TCCR5B & B11111000 | B00000001; // for PWM frequency of 31372.55 Hz

    Can you tell me if this change will cause any possible issues?

    Break....Break...

    What made you aware the void setup conflicted with the delay()

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  • in reply to colporteur

    delay() relies on micros() which relies on TIMER0.

    You can see the full code here:

    https://github.com/arduino/ArduinoCore-avr/blob/master/cores/arduino/wiring.c

    Jump to line 106 for delay() and then look at micros() right above it.

    Also also, notice how delay() is using milils() (with subtraction!) to do the actual delay time ... (which is similar to what you were trying to do in some sections of your code.)

    delay() isn't magic, it is just a loop.

  • in reply to colporteur

    I think that it helps if one can see names like "TCCR0B" and know inside that it is short for "Timer Control Counter Register" then that should immediately set-off alarm bells in one's head.

    Gough Lui said:
    Are you doing something else with the timer peripherals on the microcontroller that could interfere with the Arduino code?

    This is why I asked this in my first question ... I presume you didn't know the connection as PWM is based on a timer counter and reset threshold to generate the on/off waveform. Changing the frequency of PWM (your intention) was actually changing the frequency of the timer itself (which Arduino was relying on for delay/millis).

    I was aware of this mainly because there are some libraries out there that may improve GPIO/PWM performance that also break these functions as they reconfigure Timer0.

    As far as I know, most Arduino internal functions rely on Timer0 only. Timer5 is probably quite safe to use in that regard as that's not available on Uno/Leonardo which have only 3 timers and for which most libraries are written for. As a result, it seems unlikely to interfere, but there is always the possibility if you ever end up using library code that explicitly relies on Timer5 and modifies its parameters.

    - Gough

  • in reply to Gough Lui

    Scope, context and date are three parameters I use to evaluate results from an Internet search. The train motors were noisy using the default PWM settings. I assumed if tweaking this parameter the impacts would be listed. The search results solution I used provided no information on impacts.

    I have made the hardware changes to use another value. I have to update the code with the changes to test the board. Thank you for sharing your knowledge.