carlhako

// led_blink.c
// for 7 segment led digit display

#include <stdio.h>
#include <stdlib.h>

#define F_CPU 14745600

#include <avr/io.h>
#include <inttypes.h>
#include <avr/interrupt.h>

#include "../libnerdkits/delay.h"



// PIN DEFINITIONS:
/*

MCU - PIN - SEG
------------
PC0 - 1  - E
PC1 - 2  - D
PC2 - 4  - C
PC3 - 6  - B
PC4 - 7  - A
PC5 - 9  - F
PB5 - 10 - G

PD6 - Button 1

Letters to binary register
--------------------------
E - 00000001 - 1
D - 00000010 - 2
C - 00000100 - 4
B - 00001000 - 8
A - 00010000 - 16
F - 00100000 - 32
G - 00100000 - 32

Segments
--------
 A
F B
 G
E C
 D

Which segments make up numbers
------------------------------
# - SEG		DDRC PB5
0 - ABCDEF	63
1 - BC		12
2 - ABGED	27	on
3 - ABGCD	30	on
4 - FGBC		44	on
5 - AFGCD	54	on
6 - AFEDCG	55	on
7 - ABC		28
8 - AFGEDCB	63	on
9 - ABFGC	60	on

E - AFGED	51 	on


*/


void realtimeclock_setup() {
  // setup Timer0:
  // CTC (Clear Timer on Compare Match mode)
  // TOP set by OCR0A register
  TCCR0A |= (1<<WGM01);
  // clocked from CLK/1024
  // which is 14745600/1024, or 14400 increments per second
  TCCR0B |= (1<<CS02) | (1<<CS00);
  // set TOP to 143
  // because it counts 0, 1, 2, ... 142, 143, 0, 1, 2 ...
  // so 0 through 143 equals 144 events
  OCR0A = 143;
  // enable interrupt on compare event
  // (14400 / 144 = 100 per second)
  TIMSK0 |= (1<<OCIE0A);
}

// the_time will store the elapsed time
// in hundredths of a second.
// (100 = 1 second)
//
// note that this will overflow in approximately 248 days!
//
// This variable is marked "volatile" because it is modified
// by an interrupt handler.  Without the "volatile" marking,
// the compiler might just assume that it doesn't change in
// the flow of any given function (if the compiler doesn't
// see any code in that function modifying it -- sounds
// reasonable, normally!).
//
// But with "volatile", it will always read it from memory
// instead of making that assumption.
volatile int16_t the_time;

SIGNAL(SIG_OUTPUT_COMPARE0A) {
  // when Timer0 gets to its Output Compare value,
  // one one-hundredth of a second has elapsed (0.01 seconds).
  the_time++;
}


int main() {

realtimeclock_setup();

  // turn on interrupt handler
  sei();

  DDRB |= (1<<PB1); //pins used to switch between screen 1,2,3,4
  DDRB |= (1<<PB2); // set to high to supply current
  DDRB |= (1<<PB3);
  DDRB |= (1<<PB4);

  DDRD &= ~(1<<PC5); // set PC5 as input



 volatile int8_t min = 0; // var used for minute
 volatile int8_t sec = 0; // var used for seconds


//int8_t i;

  while(1) {

  if (the_time > 100) {
	  sec++;
	  the_time -= 100;
  }
  if (sec > 60) {
	  min++;
	  sec -= 60;
  }


  //PORTB &= ~((1<<PB1)  | (1<<PB2) | (1<<PB3) | (1<<PB4)); // turn all displays off
  PORTB |= (1<<PB4); // turn on seconds display
  display(sec % 10); // display remainder of seconds after / 10
  PORTB &= ~(1<<PB4); // turn off seconds display

  PORTB |= (1<<PB3); // turn on tens seconds display
  display(sec / 10); // display seconds / 10
  PORTB &= ~(1<<PB3); // turn off tens seconds display

  if (min > 0) { // if mins is 0 nothing will be displayed, instead of 0
	PORTB |= (1<<PB2); // turn on minuts display
	display(min % 10); // display remainder of min after / 10
	PORTB &= ~(1<<PB2); // turn off minuts display
  }

  if (min > 9) { // mins needs to be > 10 for this display to show anything
	PORTB |= (1<<PB1);// turn on 2nd minuts display
	display(min / 10); // display mins / 10
	PORTB &= ~(1<<PB1);// turn off 2nd minuts display
  }

  }

  return 0;
}


void display(uint8_t num) {

	switch(num) { // switch pins to output based on variable num
		case 0:
			DDRC = 63;  //set pins as output, once set as output default is set to low which is what we want.
			break;

		case 1:
			DDRC = 12;
			break;

		case 2:
			DDRC = 27;
			DDRB |= (1<<PB5); //1 segment is on PB also use of bitshift here or pins that power displays will be set to high impendence causing no power.
			break;

		case 3:
			DDRC = 30;
			DDRB |= (1<<PB5);
			break;

		case 4:
			DDRC = 44;
			DDRB |= (1<<PB5);
			break;

		case 5:
			DDRC = 54;
			DDRB |= (1<<PB5);
			break;

		case 6:
			DDRC = 55;
			DDRB |= (1<<PB5);
			break;

		case 7:
			DDRC = 28;
			break;

		case 8:
			DDRC = 63;
			DDRB |= (1<<PB5);
			break;

		case 9:
			DDRC = 60;
			DDRB |= (1<<PB5);
			break;

		default: // if invalid number is passed to function E is displayed.
			DDRC = 51;
			DDRB |= (1<<PB5);

	}

	delay_ms(1); // leave leds lit for 1ms, without this leds are dull;

	DDRC &= ~((1<<PC0)|(1<<PC1)|(1<<PC2)|(1<<PC3)|(1<<PC4)|(1<<PC5)); // set all pins to high impedence or input to clear display
	DDRB &= ~(1<<PB5);
}