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Troubleshooting why Arduino logical operators doesn't compute

colporteur

image

How would you write the expression to test sensors Departure (A or B) HIGH AND Arrival (A or B) HIGH?

The first else if statement shown below doesn't work. Departure A OR Departure B HIgh AND Arrival A OR Arrival B High. The OR doesn't work. Only when both Departure A AND B are HIGH the serial print. The same applies to the third else if statement both Departure A and B have to be low for the statement to function. What am I coding wrong for the OR?

      if ((digitalRead(s1DeparturePinA) == LOW || digitalRead(s1DeparturePinB) == LOW) &&
          (digitalRead(s1ArrivalPinA) == HIGH || digitalRead(s1ArrivalPinB) == HIGH))
        {
         Serial.println(F("Train on siding 1 status DEPARTURE")); 
         delay(1);
        }
      else if ((digitalRead(s1DeparturePinA) == HIGH || digitalRead(s1DeparturePinB) == HIGH)&&
               (digitalRead(s1ArrivalPinA) == HIGH || digitalRead(s1ArrivalPinB) == HIGH))
        {
          Serial.println(F("Train on siding 1 status IN TRANSIT"));
          delay(1);
        }
      else if ((digitalRead(s1DeparturePinA) == HIGH || digitalRead(s1DeparturePinB) == HIGH) &&
               (digitalRead(s1ArrivalPinA) == LOW || digitalRead(s1ArrivalPinB) == LOW))
        {
          Serial.println(F("Train on siding 1 status ARRIVAL"));
          delay(1);
          s1ArrivalDetect = LOW;
        }
      else if ((digitalRead(s1DeparturePinA) == LOW || digitalRead(s1DeparturePinB) == LOW) && 
               (digitalRead(s1ArrivalPinA) == LOW || digitalRead(s1ArrivalPinB) == LOW) &&
                s1ArrivalDetect == LOW)
        {
          Serial.println(F("Train on siding 1 status STOP"));
          delay(1);       
        trainOneOut = LOW; //train selection flip_flop L=train on siding 2
        s1ArrivalDetect = HIGH;
        digitalWrite(l1_TurnoutL, LOW);  //unset departure and arrival turnouts for train1
        digitalWrite(s1_Power, LOW);        //unset power on for train1
        digitalWrite(l1_TurnoutR, HIGH);  //set departure and arrival turnouts for train2
        digitalWrite(s2_Power, HIGH);        //set power on for train2
        }
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  • I would use some kind of linear encoder. If in your case you only have to detect the arrival and departure always in the same direction, the logic is reduced to detecting the rising edge of one sensor and the falling edge of the other.

    You can use interrupt service routines to detect both the rising edge transition and the falling edge transition.

    image


     has a good project on the subject.

    The Logical Project
    Intro I always had a lot of fun designing digital circuits that used Boolean logic, but these days it is rare to see designs with lots of discrete gates. With this little project I'm going to have some…
    By in Digital Fever > Blog
    14 comments


    I based on the same for this project that you see in the video. In this case I needed to detect the direction of movement, it's a different case but it uses the same quadrature encoder principle using a DIY magnetic linear encoder with two magnetic reed switches and a magnet.

    In this blog you can get the complete source code for this solution.

    VenTTracker #06 -  Window Sensor Prototype
    One of the main components of our ventilation routine monitoring project is the sensor for the status of doors, windows and blinds. During this week we have given a boost to the creation of that sensor…
    By in Design For A Cause 2021 > Blog
    2 comments

Reply

  • I would use some kind of linear encoder. If in your case you only have to detect the arrival and departure always in the same direction, the logic is reduced to detecting the rising edge of one sensor and the falling edge of the other.

    You can use interrupt service routines to detect both the rising edge transition and the falling edge transition.

    image


     has a good project on the subject.

    The Logical Project
    Intro I always had a lot of fun designing digital circuits that used Boolean logic, but these days it is rare to see designs with lots of discrete gates. With this little project I'm going to have some…
    By in Digital Fever > Blog
    14 comments


    I based on the same for this project that you see in the video. In this case I needed to detect the direction of movement, it's a different case but it uses the same quadrature encoder principle using a DIY magnetic linear encoder with two magnetic reed switches and a magnet.

    In this blog you can get the complete source code for this solution.

    VenTTracker #06 -  Window Sensor Prototype
    One of the main components of our ventilation routine monitoring project is the sensor for the status of doors, windows and blinds. During this week we have given a boost to the creation of that sensor…
    By in Design For A Cause 2021 > Blog
    2 comments

Children
  • in reply to javagoza

    I like the debounce idea for use on reading the sensors. I reviewed your application and got lost. Not a programmer. I then went in search of simplified code examples. I'm thinking of trying to assemble code for a test first to see if I can get a working model. I need some of that anti-aging formula to grasp this stuff:)

  • in reply to colporteur

    For example 

    In setup set the two ISRs

    // detect rising edge for switch A
attachInterrupt(digitalPinToInterrupt(s1ArrivalPinA), isrArrivalSwitchRising, RISING);

// detect falling edge for departure
attachInterrupt(digitalPinToInterrupt(s1DeparturePinB), isrDepartureSwitchFalling, FALLING);

    Then define the two ISR, two functions

    void isrArrivalSwitchRising() {
   state = TRAIN_ARRIVED 
}

void isrDepartureSwitchFalling() {
   state = TRAIN_DEPARTED 
}

    and in your loop method check for state changes

    if (state==TRAIN_ARRIVED) {
   state == TRAIN_PARKED;
   doMyArrivingStuff();
}

if(state==TRAIN_DEPARTED) {
   state == TRAIN_RUNNING;
   doMyDepartureStuff();
}

  • in reply to javagoza

    Did you hear that? That was my head hitting the desk:) I'm envious of the knowledge, yet my age creates limits on what I can use or retain.

    attachInterrupt(digitalPinToInterrupt(s1ArrivalPinA), isrArrivalSwitchRising, RISING);

    This call, if the sensor input s1ArrivalPinA is RISING (i.e. HIGH) run the isr routine? I will get this a little bits at a time.

  • in reply to colporteur

    When the input signal goes from low to high the processor will call that subroutine once, meanwhile you do not have to do anything, only wait, it is not necessary to be polling the state of the port. When the event occurs, the interruption is triggered, the processor stops doing what it was doing and calls that ISR. That's why the ISR has to be a routine that runs quickly, we can't consume many processor cycles in that routine.

    it's a good idea to do a debounce as I do in my project, here for simplicity I'm not dealing with bouncing.

  • in reply to javagoza

    It may appear I am picking and choosing topics. I confess I am, but it is not random, I have an end goal in mind. I'm a requirement guy. Is it nice to do or is there a requirement? I had to go look up the acronym ISR. It struck a cord with me. I'm just not sure if it fits.

    The operation of the train would be based on the state of the sensor. In my case would the ISR be looking for changes in the sensor states and perform an action based on the state? That essentially describes what I am trying to do.

    The sensors are HIGH when active (i.e. train parked over top) and go low when the train moves away.

    I thought I had the logic worked out with just two sensors, Departure and Arrival. The gap between the train cars caused some anomalies. With Two departure and two arrival sensors, the gap in the train cars is eliminated. I was looking to do a simple OR but it doesn't appear to be as simple as I thought.

  • in reply to colporteur

    My proposal was not to focus on the state of the sensors but on the change of state, that from my point of view simplifies the logic.

    An Arrival is a change of state of the Arrival sensor signal from low to high (RISING).

    And one Departure is a state change of the departure sensor signal from high to low (FALLING).

    Everything that happens in between I don't care.

    Not all pins can trigger interrupts. In your case, I think you are using an Arduino MEGA board, it has 6 pins (2, 3, 18, 19, 20, 21) with the possibility of enabling interrupts in case I2C is not used with pins 20 and 21. In that case you would have 4 pins only enabled for interruptions.

    https://www.arduino.cc/reference/en/language/functions/external-interrupts/attachinterrupt/