Can't get timing/trigger quite right

Using Arduino Programming Questions
1

Hi all, I've been working on this all day. My brain is fried. I can't seem to get the logic right. If anyone can advise, I would appreciate it SOOOO much.

Project:
Input: beam break sensor
Output: servo

Expected result:

  1. beam is broken and stays broken for more than 5 seconds, servo rotates
  2. beam is broken for less than 5 seconds, servo doesn't rotate

Actual result:

  1. If i start with breaking beam for less than 5 seconds, works as expected
  2. If I follow that with breaking the beam for longer than 5 s, works as expected.
  3. If I follow THAT by breaking for less than 5, it still moves the servo
/* 
  Reward with candy when piano has been pracited enough
*/
#include <Servo.h>

#define SENSORPIN 4
int servoPin = 7;
unsigned long previousMillis = 0;
const long interval = 5000; //the value is a number of milliseconds, ie 1 second
Servo myservo;
int angle = 0;   // servo position in degrees

// variables will change:
int sensorState = 0, lastState=0;         // variable for reading the pushbutton status

void setup() {
  pinMode(servoPin, OUTPUT); // initialize the servo as an output
  pinMode(SENSORPIN, INPUT); // initialize the sensor pin as an input
  digitalWrite(SENSORPIN, HIGH); // turn on the pullup
  
  Serial.begin(9600);
  myservo.attach(servoPin);
}

void loop(){
  sensorState = digitalRead(SENSORPIN);  // read the state of the pushbutton value
  unsigned long currentMillis = millis(); //amount of time passed since program started
  myservo.write(0); 
  if (!sensorState && lastState) { //beam broken, start counting how long the beam is broken
    Serial.println("Practice has started"); 
    previousMillis;
  }

  if (sensorState && !lastState && (currentMillis - previousMillis >= 5000)) { //beam UNbroken and we've practiced enough
    //previousMillis;
    Serial.println("Good job!");
    myservo.write(180);
    delay(1000);
    myservo.write(0);
    delay(1000);
    myservo.write(180);
    delay(1000);
    myservo.write(0); 
    previousMillis = currentMillis;
    } 
 
  lastState = sensorState;
}
2

Displaying previousMillis and currentMillis might show the answer. Does the millis() become too big for the unsigned long(s) to contain?

3

Maybe...
previousMillis = currentMillis;

Also... your current servo logic only triggers when the beam becomes "unbroken" after 5 seconds - is that what is should do? or should it trigger after 5 seconds of being broken regardless?

4

Good question. Either method would work. Either I practice for 30 minutes or more. and I'm alerted that I reached the time I wanted to OR I practice and then find out as a surprise if I reached time or not. :slight_smile:

I've tried previousMillis = currentMillis; everywhere so I'm wondering if it's an order of operations thing. I should probably write down the combinations I've tried because I feel like I've tried them all. :smile:

5

This needs to happen from the time the beam is first broken. In here...

6

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