LEDs blinking duration and without motion

Using Arduino LEDs and Multiplexing
9

@ HKJ-lygte , change the logic around. Do the comparison with subtraction, that way the millis() roll over has no effect. Now it has.

const byte InputPin = 3;
const byte LedPin =  13;

unsigned long timer;

void setup() {
  //Serial.begin(9600);
  pinMode(LedPin, OUTPUT);
  pinMode(InputPin, INPUT);
}

void loop() {
  // When PIR active, store millis()
  if (digitalRead(InputPin)){
    timer = millis();
  }

  // When millis() has not advanced more then 300ms from timer
  digitalWrite(ledPin, millis() - timer < 300);
}

PS 300ms is afwfully short.

@Umair_Khalid_Khan In what mode is the PIR? Retriggerable or Non-retriggerable?