#define FREQ        250   // Sampling frequency

// ----------------------- Variables for servo signal generation -------------
unsigned int  period; // Sampling period
unsigned long add = 10,loop_timer;
unsigned long now, difference;

unsigned long pulse_length_esc1 = 1000,
        pulse_length_esc2 = 1000,
        pulse_length_esc3 = 1000,
        pulse_length_esc4 = 1000;


void setup() {
  // put your setup code here, to run once:

// Set pins #4 #5 #6 #7 as outputs
    DDRD |= B11110000;
     period = (1000000/FREQ) ; // Sampling period in µs
     applyMotorSpeed();
    // Initialize loop_timer
    loop_timer = micros();

    // Turn LED off now setup is done
    digitalWrite(13, LOW);

}

void loop() {
  // put your main code here, to run repeatedly:
  
    pulse_length_esc1 = 1000;
    digitalWrite(13, HIGH); 
    applyMotorSpeed();
    delay(500);
    pulse_length_esc1 = 4000;
    digitalWrite(13, LOW); 
    applyMotorSpeed();
    delay(500);
  
  

}