relay_timer

/*
Copyright 2011 Dustin L. Westaby

----------------------------------------------------------------------
        Timed Relay Control for ATtiny2313
----------------------------------------------------------------------
Title:      relay_timer.c
Author:     Dustin Westaby
Date Created:   03/06/11
Last Modified:  03/15/11
Purpose:  Control program for relays. See included sch file for
          circuit info. Timing is input on DIP switches with 30ms
          resolution. From 0 to 420ms.
Note: Relays are connected for NC operation.  Program only engages
      relays for a brief period of time.

Compiled with AVR-GCC WinAVR

Revisions List:
03/06/11  Initial program
03/07/11  Added input to start program
03/10/11  Added timing select with 4pos DIP switch
03/15/11  Small modifications for final circuit

----------------------------------------------------------------------
*/

//--------------------------------------
//          Global Variables           |
//--------------------------------------
#define F_CPU 8000000UL  /* 8 MHz Internal Oscillator */

enum { ON, OFF };

//--------------------------------------
//              Includes               |
//--------------------------------------
#include <avr/io.h>
#include <util/delay.h>
#include <inttypes.h>

//--------------------------------------
//          Delay Subroutines          |
//--------------------------------------
void delay_ms(uint16_t ms) {
    while ( ms )
    {
        _delay_ms(1);
        ms--;
    }
}

void delay_us(uint16_t us) {
    while ( us )
    {
        _delay_us(1);
        us--;
    }
}

//--------------------------------------
//          Relay Subroutines          |
//--------------------------------------
void relay1(int command)
{
    if (command==ON)
        PORTB = (1<<PB0);
    else
        PORTB = (0<<PB0);

}

void relay2(int command)
{
    //PD3 is LED indicator
    if (command==ON)
        PORTD = (1<<PD5)|(1<<PD3);
    else
        PORTD = (0<<PD5)|(0<<PD3);

}

int button_is_pressed()
{

    // the button is pressed when bit is clear
    if (bit_is_clear(PIND, PD4))
    {
        delay_us(800);
        if (bit_is_clear(PIND, PD4)) return 1;
    }

    return 0;
}

int get_timer_selection()
{
    //resolution of 4 bit DIP selection is 30ms
    //30ms resolution was chosen due to the accuracy limitations of the AVR's RC oscilator clock
    int resolution;
    int timer_number;
    resolution = 30;
    timer_number = 0;

    //0000 = 0
    //0001 = 30*
    //0010 = 60*
    //0011 = 90
    //0100 = 120*
    //0101 = 150
    //0110 = 180
    //0111 = 210
    //1000 = 240*
    //1001 = 270
    //1010 = 300
    //1011 = 330
    //1100 = 360
    //1101 = 390
    //1110 = 420
    //1111 = 450

    // the switch is ON when bit is clear (grounded)
    if (bit_is_clear(PINB, PB1))
        timer_number+=resolution;

    if (bit_is_clear(PINB, PB2))
        timer_number+=resolution*2;

    if (bit_is_clear(PINB, PB3))
        timer_number+=resolution*4;

    if (bit_is_clear(PINB, PB4))
        timer_number+=resolution*8;

    return timer_number;
}

void ioinit (void)
{

    //PD4 is an input and requires a pull up resistor
    //PB1, PB2, PB3, PB4 are inputs and require pull-up resistors
    //All others outputs
    DDRB =  0b11100001;
    PORTB = 0b00011110;
    DDRD =  0b11101111;
    PORTD = 0b00010000;
    DDRA =  0b11111111;
    PORTA = 0b00000000;

}

//--------------------------------------
//               Main                  |
//--------------------------------------
int main (void)
{

    ioinit ();


    //start with relays off
    //relays are connected for NC operation, relays off = power on
    relay1(OFF);
    relay2(OFF);

    while(1)
    {

        //wait for button press to start
        while (!button_is_pressed());

        //run instant power program
        relay1(ON);
        relay2(ON);
        delay_ms(get_timer_selection());
        relay1(OFF);
        relay2(OFF);

        //don't let program run again for 5 seconds
        delay_ms(5000);

    }


    while(1);                       // Ending infinite loop

}