Delaying Activation Controller

Projects Programming
1

I am trying to program my arduino uno to switch on an LED when an object is at a certain range from an IR sensor for more than 2 seconds and to shut off as soon as the object moves out of this determined range. It should also be able to switch the LED on again if the object is in the required range for more than 2 seconds.

The code that I have placed here has been my best attempt of about 200 different variations. The problem is that once the object is within the correct range my sensor will actually turn on the LED but once the object moves out of range the while loop keeps running... (and i keeps increasing by 1 obviously)

I tested this code several times using a potentiometer and a threshold value and it worked fine... If you need any more information let me know.

// These constants won't change:
const int analogPin = A0; // pin that the sensor is attached to
const int ledPin = 13; // pin that the LED is attached to

void setup() {
// initialize the LED pin as an output:
pinMode(ledPin, OUTPUT);
// initialize serial communications:
Serial.begin(9600);
}

void loop() {
float analogValue = analogRead(analogPin);
int i;
i=0;
float voltage=analogValue*.00488;
// if the analog value is high enough, start adding to i:
while (voltage > 1.85 && voltage<1.96) {
i=i+1;
Serial.println(i);
analogValue = analogRead(analogPin);
float voltage=analogValue*.00488;
delay(1000);
Serial.println(voltage,2);
if (i>2){
digitalWrite(ledPin, HIGH);

}
}

if (i==0){
digitalWrite(ledPin, LOW);

Serial.println(voltage,2);
delay(1000);
}
}

2

To post:

  1. Use CTRL-T in the Arduino IDE to autoformat your code.
  2. Paste the autoformatted code between code tags (the </> button) so that we can easily see your code.

You have declared the variable voltage twice as:

 float voltage=analogValue*.00488;

so your while loop uses the voltage declared and computed outside the loop. The value computed inside the loop will never affect the while loop, which is now an infinite loop.

3

I appreciate your time and effort vaj. In the future I will try to autoformat all of my code. I removed the voltage calculation from inside the loop but that obviously didn't fix the issue. So I am exploring 'break' and 'return' actions now.

4

I guess I didn't make myself clear, or perhaps you need to read some books and tutorials about C and C++.

float voltage=analogValue*.00488;

declares a variable called voltage as being of type float, and does a calculation to provide it a value. It is the equivalent of

float voltage ;
voltage=analogValue*.00488;

You have done this twice, once outside the loop and again inside the loop. Consequently, you have TWO variables called voltage. The 'while' statement of the loop uses the first 'voltage' variable which never changes value

It is good to explore 'break' and 'return', but the solution to your current problem is simple. Inside the loop, use

voltage=analogValue*.00488;

so that you calculate the voltage but do NOT create a second variable.