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// Pin numbers are defined by the corresponding LED colors
#define YELLOW_PIN 10
// The delay amounts are declared in ms; 1 s = 1000 ms
int red_on = 2000;
// Declaring the timer function to count 1 ms of delay instead of calling the delay function
int delay_timer (int milliseconds){
 int count = 0;
 while(1)
 {
 if(TCNT0 >= 15) // Checking if 1 millisecond has passed
 {
The number of counts 
needed to reach 1 ms = 
(1,000 μs/64 μs) – 1 = 
15.625 -1 ≈ 15. Experiment 2 Lab Manual
© Dept. of EEE, Faculty of Engineering, American International University-Bangladesh (AIUB) 3
 TCNT0=0;
 count++; 
 if (count == milliseconds) //checking if required milliseconds delay has passed
 {
 count=0;
 break; // exits the loop
 }
 }
 }
 return 0;
}
void setup() {
 //define pins connected to LEDs as outputs
 pinMode(RED_PIN, OUTPUT); 
 
 //set up the timer using timer registers
 TCCR0A = 0b00000000;
 TCCR0B = 0b00000101; //setting pre-scaler for timer clock
 TCNT0 = 0;
}
void loop() {
 //to make the red LED turned on
 digitalWrite(RED_PIN, HIGH); 
 delay_timer(red_on); 
 
 //turning off the red LED
 digitalWrite(RED_PIN, LOW);
 delay_timer(red_on); 
 }