//
// hello.HC-SR501.c
//
// HC-SR501 motion detector hello-world
//    9600 baud FTDI interface
//
// Neil Gershenfeld 11/16/15
// (c) Massachusetts Institute of Technology 2015
//
// This work may be reproduced, modified, distributed,
// performed, and displayed for any purpose. Copyright is
// retained and must be preserved. The work is provided
// as is; no warranty is provided, and users accept all 
// liability.
//

#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 bit_delay_time 102 // bit delay for 9600 with overhead
#define bit_delay() _delay_us(bit_delay_time) // RS232 bit delay
#define half_bit_delay() _delay_us(bit_delay_time/2) // RS232 half bit delay
#define char_delay() _delay_ms(10) // char delay


#define led_port PORTA
#define led_direction DDRA
#define out_pins PINB
#define out_pin (1 << PB0)
#define led_pin (1 << PA7)

#define MOSFET_port PORTA // MOSFET port
#define MOSFET_direction DDRA // MOSFET direction
#define brown (1 << PA0) // MOSFET output pins
#define black (1 << PA1) // "
#define yellow (1 << PA2) // "
#define orange (1 << PA3) // "
#define on_delay() _delay_us(50) // PWM on time
#define off_delay() _delay_us(10) // PWM off time
#define PWM_count 200 // number of PWM cycles

static uint8_t count;

//
// yellow, brown PWM pulse
//
void pulse_yellow_brown() {
   for (count = 0; count < PWM_count; ++count) {
      set(MOSFET_port, yellow);
      set(MOSFET_port, brown);
      on_delay();
      clear(MOSFET_port, yellow);
      clear(MOSFET_port, brown);
      off_delay();
      }
   }
//
// yellow, black PWM pulse
//
void pulse_yellow_black() {
   for (count = 0; count < PWM_count; ++count) {
      set(MOSFET_port, yellow);
      set(MOSFET_port, black);
      on_delay();
      clear(MOSFET_port, yellow);
      clear(MOSFET_port, black);
      off_delay();
      }
   }
//
// orange, brown PWM pulse
//
void pulse_orange_brown() {
   for (count = 0; count < PWM_count; ++count) {
      set(MOSFET_port, orange);
      set(MOSFET_port, brown);
      on_delay();
      clear(MOSFET_port, orange);
      clear(MOSFET_port, brown);
      off_delay();
      }
   }
//
// orange, black PWM pulse
//
void pulse_orange_black() {
   for (count = 0; count < PWM_count; ++count) {
      set(MOSFET_port, orange);
      set(MOSFET_port, black);
      on_delay();
      clear(MOSFET_port, orange);
      clear(MOSFET_port, black);
      off_delay();
      }
   }
//
// clockwise step
//
void step_cw() {
   pulse_yellow_brown();
   pulse_yellow_black();
   pulse_orange_black();
   pulse_orange_brown();
   }
//
// counter-clockwise step
//
void step_ccw() {
   pulse_orange_brown();
   pulse_orange_black();
   pulse_yellow_black();
   pulse_yellow_brown();
   }



int main(void) {
   //
   // main
   //
   // set clock divider to /1
   //
   CLKPR = (1 << CLKPCE);
   CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0);
   //
   //initialize led pin
   //
   output(led_direction,led_pin);
   //
   // initialize MOSFET pins
   //
   clear(MOSFET_port, brown);
   output(MOSFET_direction, brown);
   clear(MOSFET_port, black);
   output(MOSFET_direction, black);
   clear(MOSFET_port, yellow);
   output(MOSFET_direction, yellow);
   clear(MOSFET_port, orange);
   output(MOSFET_direction, orange);
   //
   // main loop
   //
   while (1) {
      //
      // wait for output high
      //
      while ((out_pins & out_pin) == 0)
         ;
      step_cw();
	  set(led_port,led_pin);
      //
      // wait for output low
      //
      while ((out_pins & out_pin) != 0)
         ;
      
	  clear(led_port,led_pin);
      }
   }