// Generate a frequency with Timer0

// Global Variables

const unsigned char MSG0[21] = "T0_Freq.C           "; 
const unsigned char MSG1[21] = "N =                 "; 

unsigned int N = 8513 - 50;

// Subroutine Declarations
#include <pic18.h>

// Subroutines
#include        "lcd_portd.c"

void interrupt IntServe(void)
{
   if (TMR0IF) {
      TMR0 = -N;
      RC0 = !RC0;
      TMR0IF = 0;
      }
   }
         
// Main Routine

void main(void)
{
   unsigned char i;

   TRISA = 0;
   TRISB = 0xFF;
   TRISC = 0;
   TRISD = 0;
   TRISE = 0;
   ADCON1 = 0x0F;

   LCD_Init();                  // initialize the LCD

   LCD_Move(0,0);  for (i=0; i<20; i++) LCD_Write(MSG0[i]);
   LCD_Move(1,0);  for (i=0; i<20; i++) LCD_Write(MSG1[i]);

   Wait_ms(100);

// set up Timer0 for PS = 1
   T0CS = 0;
   T0CON = 0x88;
   TMR0ON = 1;
   TMR0IE = 1;
   TMR0IP = 1;
   PEIE = 1;
// turn on all interrupts
   GIE = 1;

   while(1) {
      LCD_Move(1,8);  LCD_Out(N, 5, 0);
      }      
   }