rtc.c

基于MEGA8的电子钟源代码

/******************************************/
  
/*  目标MCU:MEGA8   晶振:内部RC(INT) 8MHZ */
/******************************************/
//说明：ATMEGA8只有在使用内部RC振荡器，T2使用异步时钟的
//      情况下，外接的32.768KHZ的晶振才起作用。
#include<iom8v.h>
#include<macros.h>
#define fosc 8000000
#define baud 19200
unsigned char hour;
unsigned char minute;
unsigned char second;
unsigned char day;
unsigned char month;
unsigned int year;
unsigned char mon[12]={31,28,31,30,31,30,31,31,30,31,30,31};

/* 			调整时间 			 */
void putchar(unsigned char c)
	{	 
     while (!(UCSRA&(1<<UDRE)));
	 UDR=c;    
	}
/*  		字符输入函数 		 */	
unsigned char getchar(void)
  	{
	 while(!(UCSRA& (1<<RXC)));
     return UDR;
	}		
/*			字符串输出函数	   	 */	
void puts(char *s)
	{
	while (*s)
		{
		putchar(*s);
		s++;
		}	
    putchar(0x0a);//回车换行
	putchar(0x0d);
	}
/*			UART初始化				*/	
void uart_init(void)
{
// OSCCAL=read_flash(osc_address);
 UCSRB=(1<<RXEN)|(1<<TXEN)|(1<<RXCIE);//允许发送和接收
 UBRRL=(fosc/16/(baud+1))%256;
 UBRRH=(fosc/16/(baud+1))/256;
 UCSRC=(1<<URSEL)|(1<<UCSZ1)|(1<<UCSZ0);//8位数据+1位STOP位
}

void time(void)
	 {
	  if (second<60)
	  	  return;
	  else
	    {
		 second-=60;
		 if (minute<59)
		    minute++;
		 else
		   {
		    minute=0;
			if (hour<23)
			   hour++;
			  else
			    { hour=0;   
			       if(day<=mon[month-1])
				     { day++;	
					 if(((((year%4)==0)&&((year%100)!=0))||((year%400)==0))&&(month==4))
					  mon[1]=28;	}  
					     else
						 {
						   day=0;
						    if(month<13)
							  month++;
							    else
							        year++;
									if((((year%4)==0)&&((year%100)!=0))||((year%400)==0))
								       mon[1]=29;
						 }	
					}
				}
			}			 
		} 		 	  
	
//初始化
void timer2_init(void)
{
 TCCR2 = 0x00;
 ASSR  = 1<<AS2; //异步时钟
 TCNT2 = 0xE0; //定时时间1秒
 TCCR2 = (1<<CS22)|(1<<CS21)|(1<<CS20); //分频比1024,0x07
}
#pragma interrupt_handler timer2_ovf_isr:iv_TIMER2_OVF
void timer2_ovf_isr(void)
{
 TCNT2 = 0xE0;
 second++;
}
void put_time(void)
 {
  putchar(year/1000+0x30);
  putchar(year/100+0x30);
  putchar(year/10+0x30);
  putchar(year%10+0x30);
  putchar(':');
   putchar(month/10+0x30);
  putchar(month%10+0x30);
  putchar(':');
  putchar(day/10+0x30);
  putchar(day%10+0x30);
  putchar(':');
  putchar(hour/10+0x30);
  putchar(hour%10+0x30);
  putchar(':');
  putchar(minute/10+0x30);
  putchar(minute%10+0x30);
  putchar(':');
  putchar(second/10+0x30);
  putchar(second%10+0x30);  
 }
//UART接收中断 
#pragma interrupt_handler uart0_rx_isr:iv_USART_RXC
void uart0_rx_isr(void)
{
 unsigned i;
 i=UDR;
 if (i=='t')
   {
    year=(getchar()-0x30)*1000;
	year=(getchar()-0x30)*100;
	year=(getchar()-0x30)*10;
	year=year+(getchar()-0x30);
	month=(getchar()-0x30)*10;
	month=month+(getchar()-0x30);
	day=(getchar()-0x30)*10;
	day=day+(getchar()-0x30);
    hour=(getchar()-0x30)*10;
	hour=hour+(getchar()-0x30);
	minute=(getchar()-0x30)*10;
	minute=minute+(getchar()-0x30);
	second=(getchar()-0x30)*10;
	second=second+(getchar()-0x30);
   }
} 
//main程序
void main(void)
{
 unsigned char second_old;
 uart_init(); 
 timer2_init();
 TIMSK =1<<TOIE2;

 SEI();
 while(1)
   {
    if (second!=second_old)
        {
		 time();
		 second_old=second;
		 put_time();
		}
   }	
}