hi i am a beginner with micro so i wanted to try to build a clock and here is the code

sbit LCD_RS at RB4_bit;
sbit LCD_EN at RB5_bit;
sbit LCD_D4 at RB0_bit;
sbit LCD_D5 at RB1_bit;
sbit LCD_D6 at RB2_bit;
sbit LCD_D7 at RB3_bit;

sbit LCD_RS_Direction at TRISB4_bit;
sbit LCD_EN_Direction at TRISB5_bit;
sbit LCD_D4_Direction at TRISB0_bit;
sbit LCD_D5_Direction at TRISB1_bit;
sbit LCD_D6_Direction at TRISB2_bit;
sbit LCD_D7_Direction at TRISB3_bit;

  char txt2[10];
  char txt1[10];
  int  x=0;
  int y=0;
   void main(){lcd_cmd( _LCD_CURSOR_OFF);
   TRISB =0;
   T0CON =0b10001111;
    Lcd_Init();
    while(tmr0h < 0b000011111){}
    while(tmr0l < 0b01000011){}
    x++;
    T0CON =0b00001111;
    tmr0h=0;
    tmr0l=0;
  if(x==60){x=0;y++;}
  lcd_out (1,1,"time is ");
  inttostr(x,txt1);
  inttostr(y,txt2);
  ltrim(txt1);
  ltrim(txt2);
  lcd_out(2,1,"m=");
  lcd_out_cp(txt2);
  lcd_out(2,9,"s=");
  lcd_out_cp(txt1);


}

i don't know what is wrong but every time i come near a timer i mess up could some one please help me i am using a 18f452 pic and a 4 MHz cristeal

 

can any one help me please

 

Hi mhghost, I saw your other thread too.

I think the very first thing you need to do is work out HOW to get exact seconds, and make sure that works.

Personally I prefer the simplicity and tunability of a Bresenham type system, which can make perfect seconds from any xtal speed.

This page has a lot of C examples;
http://romanblack.com/one_sec.htm

Here is one, to give actual seconds from a TMR0 and your 4MHz xtal;

  // uses 1 variable; unsigned long bres
  // gets here every TMR0 int (every 256 ticks)

  bres += 256;         // add 256 ticks to bresenham total

  if(bres >= 1000000)  // if reached 1 second!
  {
    bres -= 1000000;   // subtract 1 second, retain error
    do_1sec_event();   // update clock, etc
  }

That code goes inside your TMR0 overflow interrupt, and TMR0 prescaler set to 1:1.

For now I would concentrate on getting the interrupt and that code working, and just make it toggle a LED every second.

Then you can compare that to a household clock, and if the flashing LED is keeping good time you can then add more code, to count seconds and minutes.

 

thanks man

i will try it