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);

}