Probleme mit LCDUhr

/*****************************************************
This program was produced by the
CodeWizardAVR V1.24.2c Evaluation
Automatic Program Generator
© Copyright 1998-2004 Pavel Haiduc, HP InfoTech s.r.l.
http://www.hpinfotech.ro
e-mail:office@hpinfotech.ro

Project :
Version :
Date    : 13.05.2005
Author  : Freeware, for evaluation and non-commercial use only
Company :
Comments:


Chip type           : AT90S8515
Clock frequency     : 3,686411 MHz
Memory model        : Small
External SRAM size  : 0
Data Stack size     : 128
*****************************************************/

#include <90s8515.h>

// Alphanumeric LCD Module functions
#asm
   .equ __lcd_port=0x15 ;PORTC
#endasm
#include <lcd.h>
#include <stdio.h>
char timer;
char seconds=-1;
char minutes=0;
char hours=0;
char szTemp[16+1];
void watch();
// Timer 0 overflow interrupt service routine
interrupt [TIM0_OVF] void timer0_ovf_isr(void)
{
// Reinitialize Timer 0 value
TCNT0=0xC7;
// Place your code here
if (timer>0) timer--;
}

// Declare your global variables here

void main(void)
{
// Declare your local variables here

// Input/Output Ports initialization
// Port A initialization
// Func7=In Func6=In Func5=In Func4=In Func3=In Func2=In Func1=In 
Func0=In
// State7=T State6=T State5=T State4=T State3=T State2=T State1=T 
State0=T
PORTA=0x00;
DDRA=0x00;

// Port B initialization
// Func7=Out Func6=Out Func5=Out Func4=Out Func3=Out Func2=Out Func1=Out 
Func0=Out
// State7=1 State6=1 State5=1 State4=1 State3=1 State2=1 State1=1 
State0=1
PORTB=0xFF;
DDRB=0xFF;

// Port C initialization
// Func7=Out Func6=Out Func5=Out Func4=Out Func3=Out Func2=Out Func1=Out 
Func0=Out
// State7=0 State6=0 State5=0 State4=0 State3=0 State2=0 State1=0 
State0=0
PORTC=0x00;
DDRC=0xFF;

// Port D initialization
// Func7=In Func6=In Func5=In Func4=In Func3=In Func2=In Func1=In 
Func0=In
// State7=T State6=T State5=T State4=T State3=T State2=T State1=T 
State0=T
PORTD=0x00;
DDRD=0x00;

// Timer/Counter 0 initialization
// Clock source: System Clock
// Clock value: 57,600 kHz
TCCR0=0x03;
TCNT0=0xC7;

// Timer/Counter 1 initialization
// Clock source: System Clock
// Clock value: Timer 1 Stopped
// Mode: Normal top=FFFFh
// OC1A output: Discon.
// OC1B output: Discon.
// Noise Canceler: Off
// Input Capture on Falling Edge
TCCR1A=0x00;
TCCR1B=0x00;
TCNT1H=0x00;
TCNT1L=0x00;
OCR1AH=0x00;
OCR1AL=0x00;
OCR1BH=0x00;
OCR1BL=0x00;

// External Interrupt(s) initialization
// INT0: Off
// INT1: Off
GIMSK=0x00;
MCUCR=0x00;

// Timer(s)/Counter(s) Interrupt(s) initialization
TIMSK=0x02;

// Analog Comparator initialization
// Analog Comparator: Off
// Analog Comparator Input Capture by Timer/Counter 1: Off
// Analog Comparator Output: Off
ACSR=0x80;

// LCD module initialization
lcd_init(16);

// Global enable interrupts
#asm("sei")

while (1)
      {
      // Place your code here
      if (timer==0) watch();
      };
}
void watch(void)
{
  timer=10000;
  seconds++;
         if (seconds>59)
     {
       seconds=0;
       minutes++;
       }
        else if (minutes>59)
     {
        minutes=0;
          hours++;
        }
        else if (hours>23)
        {
         hours=0;
       }

       sprintf(szTemp,"Time:   %02d:%02d:%02d",hours,minutes,seconds);
       lcd_gotoxy(0,0);
       lcd_puts(szTemp);

}


Die LCD Uhr gibt leider keinen Sekunden takt aus und zählt hoch!

Vielleicht kann mir da einer weiter helfen!

Gruß