▲Datasheet
http://extremeelectronics.co.in/avr-projects/avr-project-relay-timer-with-atmega8-avr-mcu/
▲Example
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/******************************************************
A Simple Device Timer project designed using ATmega8
AVR MVU. The Timer is usefully for keeping a device
"ON" for a specific period of time. After the set time
elapse the timer automatically turns the load off.
The Timer uses a standard 16x2 lcd module for user interface
UI. User can set the time using a 3 button keypad.
After that Timer is started. While count down is in
progress, the time left is displayed on screen.
The program use our LCD driver library more details
of which can be found in Web site.
Use avr-gcc + AVR Studio to compile.
Author: Avinash Gupta
E:Mail: me@avinashgupta.com
Web: www.eXtremeElectronics.co.in
*** THIS PROJECT IS PROVIDED FOR EDUCATION/HOBBY USE ONLY ***
*** NO PROTION OF THIS WORK CAN BE USED IN COMMERIAL ***
*** APPLICATION WITHOUT WRITTEN PERMISSION FROM THE AUTHOR ***
EVERYONE IS FREE TO POST/PUBLISH THIS ARTICLE IN
PRINTED OR ELECTRONIC FORM IN FREE/PAID WEBSITES/MAGAZINES/BOOKS
IF PROPER CREDIT TO ORIGINAL AUTHOR IS MENTIONED WITH LINKS TO
ORIGINAL ARTICLE
Copyright (C) 2008-2009 eXtreme Electronics, India.
******************************************************/
#include <avr/io.h>
#include <avr/interrupt.h>
#include "lcd.h"
//Connection of Load
#define LOAD_DDR DDRC //데이터방향(Direction) C포트에서
#define LOAD_PORT PORTC //어느포트를 사용할지 결정
#define LOAD_POS PC0
//Global variable for the clock system
volatile unsigned int clock_millisecond=0;
volatile char clock_second=0;
volatile char clock_minute=0;
volatile char clock_hour=0;
void Wait(uint8_t n)
{
uint8_t i,temp;
temp=n*28;
for(i=0;i<temp;i++)
_delay_loop_2(0);
}
void LoadOn()
{
LOAD_PORT|=(1<<LOAD_POS);
}
void LoadOff()
{
LOAD_PORT&=(~(1<<LOAD_POS));
}
main()
{
while(1)
{
LOAD_DDR|=(1<<LOAD_POS);
LoadOff();
//Enable Pullups on Keypad
PORTB|=((1<<PB2)|(1<<PB1)|(1<<PB0));
int8_t hr,min; //Target Time
hr=min=0;
//Initialize the LCD Subsystem
InitLCD(0);
//Clear the display
LCDClear();
//Set up the timer1 as described in the
//tutorial
TCCR1B=(1<<WGM12)|(1<<CS11)|(1<<CS10);
OCR1A=250;
//Enable the Output Compare A interrupt
TIMSK|=(1<<OCIE1A);
//Enable interrupts globally
sei();
LCDClear();
LCDWriteString(" Welcome ");
LCDWriteStringXY(0,1," Relay Timer ");
Wait(4);
LCDClear();
LCDWriteString("Set Time - 00:00");
LCDWriteStringXY(0,1," Start ^");
uint8_t selection=1;
uint8_t old_pinb=PINB;
while(1)
{
while((PINB & 0b00000111) == (old_pinb & 0b00000111));
//Input received
if(!(PINB & (1<<PINB2)) && (old_pinb & (1<<PB2)))
{
//Selection key Pressed
selection++;
if(selection==3)
selection =0;
}
if(!(PINB & (1<<PINB1)) && (old_pinb & (1<<PB1)))
{
//Up Key Pressed
if(selection == 1)
{
//Hour is selected so increment it
hr++;
if(hr == 100)
hr =0;
}
if(selection == 2)
{
//Min is selected so increment it
min++;
if(min == 60)
min =0;
}
if(selection == 0)
{
//Start Selected
break;
}
}
if(!(PINB & (1<<PINB0)) && (old_pinb & (1<<PB0)))
{
//Down Key Pressed
if(selection == 1)
{
//Hour is selected so decrement it
hr--;
if(hr == -1)
hr =99;
}
if(selection == 2)
{
//Min is selected so decrement it
min--;
if(min == -1)
min =59;
}
if(selection == 0)
{
//Start Selected
break;
}
}
old_pinb=PINB;
//Update Display
LCDClear();
LCDWriteString("Set Time - 00:00");
LCDWriteStringXY(0,1," Start ");
//Hour
LCDWriteIntXY(11,0,hr,2);
//Minute
LCDWriteIntXY(14,0,min,2);
if(selection == 0)
LCDWriteStringXY(0,1,">");
if(selection == 1)
LCDWriteStringXY(11,1,"^");
if(selection == 2)
LCDWriteStringXY(14,1,"^");
_delay_loop_2(0);
_delay_loop_2(0);
_delay_loop_2(0);
_delay_loop_2(0);
_delay_loop_2(0);
_delay_loop_2(0);
_delay_loop_2(0);
_delay_loop_2(0);
}
//Start the Load
LoadOn();
//Now start the timer
clock_hour = hr;
clock_minute = min;
clock_second =0;
LCDClear();
LCDWriteString(" Power Off In ");
while(1)
{
LCDWriteIntXY(4,1,clock_hour,2);
LCDWriteString(":");
LCDWriteIntXY(7,1,clock_minute,2);
LCDWriteString(":");
LCDWriteIntXY(10,1,clock_second,2);
if((clock_hour == 0) && (clock_minute == 0) && (clock_second == 0))
{
//Time Out
LoadOff();
LCDClear();
LCDWriteString("Load Turned Off");
while(1)
{
LCDWriteStringXY(0,1,"*Press Any Key*");
Wait(1);
LCDWriteStringXY(0,1," ");
Wait(1);
if((~PINB) & 0b00000111)
break;
}
break;
}
_delay_loop_2(0);
_delay_loop_2(0);
_delay_loop_2(0);
_delay_loop_2(0);
}
//Continue again
}
}
//The output compate interrupt handler
//We set up the timer in such a way that
//this ISR is called exactly at 1ms interval
ISR(TIMER1_COMPA_vect)
{
clock_millisecond++;
if(clock_millisecond==1000)
{
clock_second--;
clock_millisecond=0;
if(clock_second==-1)
{
clock_minute--;
clock_second=59;
if(clock_minute==-1)
{
clock_hour--;
clock_minute=59;
}
}
if( clock_hour == 1 && clock_minute==0 && clock_sec)
{
//1번LED가 켜진다
}
}
}
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