// Measure time to 100ns

// Global Variables

const unsigned char MSG0[21] = "T0_Time.C           "; 
const unsigned char MSG1[21] = "                    ";     

unsigned long int TIME;

// Subroutine Declarations
#include <pic18.h>

// Subroutines
#include        "lcd_portd.c"

void interrupt IntServe(void)
{
   if (TMR0IF) {
      TIME = TIME + 0x10000;
      TMR0IF = 0;
      }
   }
 

         
// Main Routine

void main(void)
{
   unsigned char i;
   unsigned long int TIME1, TIME2;

   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;

   TIME = 0;


   while(1) {
      TIME1 = TIME + TMR0;
      Wait_ms(1000);
      TIME2 = TIME + TMR0;
      LCD_Move(1,0);  LCD_Out(TIME2 - TIME1, 10, 7);
      }      
   }