How to detect zero crosing with Arduino Uno

Projects Programming
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I would appreciate if someone could help me.

Here is my connection to Arduino:

1600×1200 166 KB

wires, yellow and red are for AC current. Other 3 in my arduino, orange pin 2, blue ground and red 5V power.

I am using h11aa1 optoisolator.

Here is my code:

const uint8_t ledPin = 13;                          // Digital output pin that has the on board LED
const uint8_t zeroPin = 2;                          // Digital input pin to which the zero crossing detector is connected

uint8_t zeroCounter = 0;
bool zeroState = 0;
bool ledState = 0;

void setup() {
  Serial.begin(9600);
  pinMode( ledPin , OUTPUT );                       // Enable output driver for LED pin
  pinMode( zeroPin , INPUT );
}

void loop() {

 Serial.println(digitalRead(zeroPin));
  while ( digitalRead(zeroPin) == zeroState ) { // Wait for the state of the zero crossing detector to change
  zeroState != zeroState;
  zeroCounter++;
  if ( zeroCounter == 50 ) {         // Every 50 zero crossings change the LED state
  Serial.println(zeroState);
    ledState != ledState;
    digitalWrite( ledPin , ledState );
    zeroCounter = 0;
  }
  };
}

I get always 1 for digitalRead(zeroPin) and because of it Serial.println(zeroState) will never run...

Anyone can help me make this work?