//
//
// desk.c
//
// Charlieplexed array activated by step response sensor
//
// Adapted from code by Neil Gershenfeld and Matt Blackshaw
// 12/14/14
//

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

#define output(directions,pin) (directions |= pin) // set port direction for output
#define input(directions,pin) (directions &= (~pin)) // set port direction for input 
#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 charge_delay() _delay_us(1) // charge delay 1
#define settle_delay() _delay_us(100) // settle delay
#define char_delay() _delay_ms(10) // char delay

//#define activate 436 //sense value with FabISP attached
#define activate 515 // sense value without FabISP
//#define remain 440 // sense value for desk to remain lit with FabISP
#define remain 525 // sense value for desk to remain lit without FabISP
#define on_delay 700 // cycles for desk to remain lit after activated

//Step Response Pins
#define charge_port PORTA // set port A for for charge pin (PA7)
#define charge_direction DDRA // set data direction register for charge pin

#define charge_pin (1 << PA7) // set charge pin (shield in step response circuit)
#define sense_pin (1 << PA6) // set sense pin 

//Charlieplexing Pins
#define led_delay() _delay_ms(1) // LED delay
#define led_port PORTA // set port A for LED pins
#define led_direction DDRA // set data direction register for LED pins

#define A (1 << PA1) // row 1
#define B (1 << PA2) // row 2
#define C (1 << PA3) // row 3
#define D (1 << PA4) // row 4

void flash(uint8_t from, uint8_t to, uint8_t delay) {
   //
   // source from, sink to, flash
   //
   static uint8_t i;
   set(led_port,from);
   clear(led_port,to);
   output(led_direction,from);
   output(led_direction,to);
   for (i = 0; i < delay; ++i)
       led_delay();
   input(led_direction,from);
   input(led_direction,to);
   }

void flash_multi(uint8_t from1, uint8_t from2, uint8_t from3, uint8_t to, uint8_t delay) {
	//
	// achieve better brightness by turning multiple 
	// LED's on at the same time
	//
	static uint8_t i;
	set(led_port,from1);
	set(led_port,from2);
	set(led_port,from3);
	clear(led_port,to);
	output(led_direction,from1);
	output(led_direction,from2);
	output(led_direction,from3);
	output(led_direction,to);
	for (i = 0; i < delay; ++i)
		led_delay();
	input(led_direction,from1);
	input(led_direction,from2);
	input(led_direction,from3);
	input(led_direction,to);
}

void led_cycle(uint8_t number, uint8_t delay) {
   //
   // cycle through LEDs
   //
   uint8_t i;
   for (i = 0; i < number; ++i) {
      flash(A,B,delay);
      flash(A,C,delay);
      flash(A,D,delay);
      flash(B,A,delay);
      flash(B,C,delay);
      flash(B,D,delay);
      flash(C,A,delay);
      flash(C,B,delay);
      flash(C,D,delay);
      flash(D,A,delay);
      flash(D,B,delay);
      flash(D,C,delay);
   }
}

void led_on(uint8_t number, uint8_t delay) {
   //
   // cycle through multiplte LED's at a time
   //
   uint8_t i;
      for (i = 0; i < number; ++i) {
      flash_multi(B,C,D,A,delay);
	  flash_multi(A,C,D,B,delay);
	  flash_multi(A,B,D,C,delay);
	  flash_multi(A,B,C,D,delay);
	  }
}

int check_pin(unsigned char pin) {
   unsigned char up_lo,up_hi,down_lo,down_hi;
   int up_value, down_value, value;
   
   //
   // set the A/D pin
   //
      ADMUX = (0 << REFS1) | (0 << REFS0) //Vcc ref on t44
      | (0 << ADLAR) // right adjust
	  | (1 << MUX2) | (1 << MUX1) | (0 << MUX0); //PA6 on t44

   //
   // settle, charge, and wait
   //
   settle_delay();
   set(charge_port, charge_pin);
   charge_delay();
   
   //
   // initiate conversion
   //
   ADCSRA |= (1 << ADSC);
   
   //
   // wait for completion
   //
   while (ADCSRA & (1 << ADSC))
	   ;

   //
   // save result
   //
   up_lo = ADCL;
   up_hi = ADCH;

   //
   // settle, discharge, and wait
   //
   settle_delay();
   clear(charge_port, charge_pin);
   charge_delay();
      
   //
   // initiate conversion
   //
   ADCSRA |= (1 << ADSC);
   
   //
   // wait for completion
   //
   while (ADCSRA & (1 << ADSC))
	   ;

   //
   // save result
   //
   down_lo = ADCL;
   down_hi = ADCH;
   
   //
   // process result
   //
   up_value = 256*up_hi + up_lo;
   down_value = 256*down_hi + down_lo;
   value = (up_value + (1023 - down_value))/2.0;

   return value;
   }

int main (void) {

	//
	// set clock divider to /1
	//
	CLKPR = (1 << CLKPCE);
	CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0);
	
	//
	// initialize output pins
	//
	clear(charge_port, charge_pin);
	output(charge_direction, charge_pin);
	
	//
	// intialize A/D
	//
      ADMUX = (0 << REFS1) | (0 << REFS0) //Vcc ref t44
      | (0 << ADLAR) // right adjust
	  | (1 << MUX2) | (1 << MUX1) | (0 << MUX0); //PA6 t44
	  ADCSRA = (1 << ADEN) // enable
		| (1 << ADPS2) | (1 << ADPS1) | (1 << ADPS0); // prescaler /128

	//
	//main loop
	//
	while(1) {
		int value = check_pin(sense_pin);
		int i=0;
		int bright = 0.8*on_delay;

		while (value < activate) { // threshold for sensing proximity
			i=i++;
			if (i==1){
				led_cycle(1,40); // LED initialization sequence
				led_on(1,50);
			}
			
			int t=0;
			while(t < on_delay){
				t=t++;
				if ( t < bright){
					//
					// hold LED's on for specified time
					//
					led_on(1,1);
					value = check_pin(sense_pin); // checking for user activity
					if (value < remain) { 
						t = 0; // restart timer if user is active
					}
				}
				else if ( t > bright){ 
					//
					// dim lights to indicate imminent deactivation
					//
					led_cycle(1,1);
					value = check_pin(sense_pin); // checking for user activity
					if (value < remain) { 
						t = 0; // restart timer if user is active
					}
				}
			}
		}
	}
}