//Original code by Neil Gershenfeld, modified by Vaibhav Saxena

#include <avr/io.h>
#include <util/delay.h>

#define output(directions,pin) (directions |= pin) // set port direction for output
#define set(port,pin) (port |= pin) // set port pin
#define clear(port,pin) (port &= (~pin)) // clear port pin
#define pin_test(pins,pin) (pins & pin) // test for port pin
#define bit_test(byte,bit) (byte & (1 << bit)) // test for bit set
#define position_delay() _delay_ms(1000)

#define PWM_port PORTA
#define PWM_direction DDRA
#define PWM_pin_0 (1 << PA6)
#define PWM_pin_1 (1 << PA7)

#define loop_count 30

int main(void) {
   //
   // main
   //
   uint8_t i;
   //
   // set clock divider to /1
   //
   CLKPR = (1 << CLKPCE);
   CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0);
   //
   // set PWM pins to output
   //
   clear(PWM_port, PWM_pin_0);
   output(PWM_direction, PWM_pin_0);
   clear(PWM_port, PWM_pin_1);
   output(PWM_direction, PWM_pin_1);
   //
   // main loop
   //
   while (1) {
      for (i = 0; i < loop_count; ++i) {
         set(PWM_port,PWM_pin_0);
         set(PWM_port,PWM_pin_1);
         _delay_us(700);
         clear(PWM_port,PWM_pin_0);
         clear(PWM_port,PWM_pin_1);
         _delay_us(19300);
         }
      for (i = 0; i < loop_count; ++i) {
         set(PWM_port,PWM_pin_0);
         set(PWM_port,PWM_pin_1);
         _delay_us(1100);
         clear(PWM_port,PWM_pin_0);
         clear(PWM_port,PWM_pin_1);
         _delay_us(18900);
         }
      for (i = 0; i < loop_count; ++i) {
         set(PWM_port,PWM_pin_0);
         set(PWM_port,PWM_pin_1);
         _delay_us(1500);
         clear(PWM_port,PWM_pin_0);
         clear(PWM_port,PWM_pin_1);
         _delay_us(18500);
         }
       for (i = 0; i < loop_count; ++i) {
         set(PWM_port,PWM_pin_0);
         set(PWM_port,PWM_pin_1);
         _delay_us(1900);
         clear(PWM_port,PWM_pin_0);
         clear(PWM_port,PWM_pin_1);
         _delay_us(18100);
         }
       for (i = 0; i < loop_count; ++i) {
         set(PWM_port,PWM_pin_0);
         set(PWM_port,PWM_pin_1);
         _delay_us(2300);
         clear(PWM_port,PWM_pin_0);
         clear(PWM_port,PWM_pin_1);
         _delay_us(17700);
         }
       for (i = 0; i < loop_count; ++i) {
         set(PWM_port,PWM_pin_0);
         set(PWM_port,PWM_pin_1);
         _delay_us(2700);
         clear(PWM_port,PWM_pin_0);
         clear(PWM_port,PWM_pin_1);
         _delay_us(17300);
         }
      for (i = 0; i < loop_count; ++i) {
         set(PWM_port,PWM_pin_0);
         set(PWM_port,PWM_pin_1);
         _delay_us(2300);
         clear(PWM_port,PWM_pin_0);
         clear(PWM_port,PWM_pin_1);
         _delay_us(17700);
         }
      for (i = 0; i < loop_count; ++i) {
         set(PWM_port,PWM_pin_0);
         set(PWM_port,PWM_pin_1);
         _delay_us(1900);
         clear(PWM_port,PWM_pin_0);
         clear(PWM_port,PWM_pin_1);
         _delay_us(18100);
         }
      for (i = 0; i < loop_count; ++i) {
         set(PWM_port,PWM_pin_0);
         set(PWM_port,PWM_pin_1);
         _delay_us(1500);
         clear(PWM_port,PWM_pin_0);
         clear(PWM_port,PWM_pin_1);
         _delay_us(18500);
         }
      for (i = 0; i < loop_count; ++i) {
         set(PWM_port,PWM_pin_0);
         set(PWM_port,PWM_pin_1);
         _delay_us(1100);
         clear(PWM_port,PWM_pin_0);
         clear(PWM_port,PWM_pin_1);
         _delay_us(18900);
         } 
      for (i = 0; i < loop_count; ++i) {
         set(PWM_port,PWM_pin_0);
         set(PWM_port,PWM_pin_1);
         _delay_us(700);
         clear(PWM_port,PWM_pin_0);
         clear(PWM_port,PWM_pin_1);
         _delay_us(19300);
         }  
      }
   }