//ECE 476 Final Project
//Ultrasonic ParKontroller
//Mauricio Rodriguez Saenz (mar97), James Juwon Lee (jjl49)
//Spring 2007

#include <Mega32.h>
#include <delay.h>
#include <stdio.h>

#define begin {
#define end   }

#define terminator 15			//Hex value for the enter key
#define LCDwidth 16				//LCD fits 16 characters
char lcd_buffer[17];

int pulse_counter;		//counts continuous pulses that did not get a pong

int light_timer;		//var used to flash LEDs

int pong_timer;			//counts how many cycles it took to receive a pong

int count;				//counter used to create pulses for the ping

int v1, v2, v3, v4, v5, v6, v7;	//vars used to determine a running average of the distance measured

int avg;				//holds running average value of distance measured

int total_count;		//debugging var used for LCD display

int dist;				//value of distance measured

char c;					//debugging var used for LCD display

int timer;				//used to create sound pulses

//#asm
//        .equ __lcd_port=0x15
//#endasm

//#include <lcd.h> // LCD driver routines

//procedure that flashes LEDs
void light_flashing(void);

//This interrupt works with timer2
//It runs at 160 kHz and on Compare on Match it clears OC2 on compare
interrupt [TIM2_COMP] t2_compare(void)
begin
		//divides the interrupt by four to create 40 kHz pulses that drive the emitter
		//Usually sends 5 pulses at a time to enhance functionality
		//although sometimes it works better with less or more pulses
		//set the output of PORTB.0 to high
		//only PORTB.0 is set as an output
    	if((count==0) || (count==4) || (count==8) || (count==12) || (count==16))// || (count==20))
		begin
			PORTB = 0xff;

		end
		//clears PORTB.0
		if((count==2) || (count==6) || (count==10) || (count==14) || (count==18))// || (count==22))
		begin
		   	PORTB = 0xfe;

        if (count==2)
        begin
			//after first high we set the timer to run
		   	pong_timer = 0;
       	end
		   	TCNT1 = 0;
		end
		count++;
		//after an approriate waiting time for the pong we reset vars to send pulses again
		//we wait 4.375 mSec
		if(count==700)
		begin
			count = 0;
      		pulse_counter++;
		end

    pong_timer++;

end

//Procedure that flases LEDs according to the distance of the object to the sensors
//We have 6 different ranges
//Limited by the minimum and maximum distance that can be read
void light_flashing(void)
begin
	light_timer++;
	if ((avg>0) && (avg <= 15))
  	begin
  		PORTA = 0x3f;
  	end

  	else if ((avg > 15) && (avg <= 20))
  	begin
  		PORTA = 0x1f;
  	end

	else if ((avg > 20) && (avg <= 25))
  	begin
  		PORTA = 0x0f;
  	end

  	else if ((avg > 25) && (avg <= 30))
  	begin
  		PORTA = 0x07;
  	end

  	else if ((avg > 30) && (avg <= 35))
  	begin
  	 	PORTA = 0x03;
  	end

  	else if (avg > 35)
  	begin
  	 	PORTA = 0x01;

  	end
end

//Procedure that emits sound according to the distance of the object to the sensors
//We have 6 different ranges
//Limited by the minimum and maximum distance that can be read
//We produce the beeping sound by setting and clearing TCCR0
//When set TCCR0 runs at approximately 4 kHz toggling OC0
void sound_gen(void)
begin
		if(timer==0)
		begin
		  	TCCR0=0;
		end
		if((avg>0) && (avg <= 15))
		begin
			if(timer==3)
			begin
				TCCR0 = 0x1c;
			end
			timer++;
			if(timer>=6)
			begin
		 		timer = 0;
			end
		end
		if((avg>15) && (avg <= 20))
		begin
			if(timer==5)
			begin
				TCCR0 = 0x1c;
			end
			timer++;
			if(timer>=10)
			begin
		 		timer = 0;
			end
		end
		if((avg>20) && (avg <= 25))
		begin
			if(timer==6)
			begin
				TCCR0 = 0x1c;
			end
			timer++;
			if(timer>=12)
			begin
		 		timer = 0;
			end
		end
		if((avg>25) && (avg <= 30))
		begin
			if(timer==7)
			begin
				TCCR0 = 0x1c;
			end
			timer++;
			if(timer>=14)
			begin
		 		timer = 0;
			end
		end
		if((avg>30) && (avg <= 35))
		begin
			if(timer==8)
			begin
				TCCR0 = 0x1c;
			end
			timer++;
			if(timer>=16)
			begin
		 		timer = 0;
			end
		end
		if(avg>35)
		begin
			if(timer==9)
			begin
				TCCR0 = 0x1c;
			end
			timer++;
			if(timer>=18)
			begin
		 		timer = 0;
			end
		end

end


void main(void)
begin

  	TCCR2=0x09;			//16 MHz clock and CTC = 160 kHz
	OCR2 = 49;

	TCCR0 = 0;
	OCR0 = 7;

	//Only timer2 is enabled to interrupt
	//in this way we ensure that timer0 does not interfere with our main timer
	TIMSK = 0x80;


	DDRB = 0x01;	//PortB is an input, except for PORTB.0
	PORTB = 0x00;
	

	DDRA = 0xff;	//PortA is an output
	PORTA = 0;

  	pulse_counter = 0;

	light_timer = 0;
	
 	pong_timer = 0;

    count = 0;

    c=1;

    v1=0;
    v2=0;
    v3=0;
    v4=0;
    v5=0;
    v6=0;
    v7=0;

    total_count = 0;

    timer = 0;

	//This code we keep at hand for debugging
	/*
	lcd_init(LCDwidth);      	//initialize the display
	lcd_clear();
	*/
	//PushState = NoPush;

	//Example LCD display
	/*
		lcd_clear();

		lcd_gotoxy(0,1);
		sprintf(lcd_buffer,"%-i",value);
		lcd_puts(lcd_buffer);

		lcd_gotoxy(0,0);
		lcd_putsf("DONE!! HIT C");
	*/

	//lcd_init(LCDwidth);      	//initialize the display
   	//lcd_clear();

	#asm
	sei
	#endasm

	while(1)
	begin

		//Only goes in if all 5 pulses have been sent
		//reason being that when emiting the pulses the receiver gets some noise that 
		//could be taken as a receive signal
		if ((count>=40) && (PINB.1))
		begin

			//first thing we do is store the number of cycles that elapsed before receiving pong
			v1=pong_timer;
			//resolution comes out to 16 kHz or 6.25 micros per tick
			// 6.25 microSec * 340 m/Sec = .2125 cm
			v1 = ((int)(((double)v1)*.2125)/2.0);     //distance calculated in cm
			
			pulse_counter = 0;

			//calculation of running average with previous 7 readings
			avg = (v1+v2+v3+v4+v5+v6+v7)/7;
			v2 = v1;
			v3 = v2;
			v4 = v3;
			v5 = v4;
			v6 = v5;
			v7 = v6;
			total_count++;

			//With the average calculated we emit sound
			sound_gen();
			
			//Debugging code that displays useful info on LCD
			/*
			if ((c==1) && (total_count==7))
			begin
				lcd_clear();
				lcd_gotoxy(0,0);
				sprintf(lcd_buffer,"%-i",dist);
				lcd_puts(lcd_buffer);
				lcd_gotoxy(0,1);
				sprintf(lcd_buffer,"%-i",v1);
				lcd_puts(lcd_buffer);

				lcd_gotoxy(0,0);
				lcd_putsf("Distance = ");
				lcd_gotoxy(11,0);
				sprintf(lcd_buffer,"%-i",avg);
				lcd_puts(lcd_buffer);
				c++;
				total_count = 0;
			end
			/*
			if ((c==2) && (total_count==7))
			begin
				lcd_gotoxy(8,0);
				sprintf(lcd_buffer,"%-i",avg);
				lcd_puts(lcd_buffer);
				c++;
				total_count = 0;
			end

			if ((c==3) && (total_count==7))
			begin
				lcd_gotoxy(14,0);
				sprintf(lcd_buffer,"%-i",avg);
				lcd_puts(lcd_buffer);
				c++;
				total_count = 0;
			end
			*/

			light_flashing();
		end

		//After 20 pulses without a pong it goes into OFF mode
		if(pulse_counter >= 20)
		begin
			PORTA = 0x00;
			TCCR0 = 0;
		end

   end // end while
end  //end main