//
// Rev counter
//

#include <P16f84.h>
#include <displays.h>

//
// Define software version strings

const unsigned char VersionString1[]="V1.02";
const unsigned char VersionString2[]="19/02/2006";

#include "RevCount-vars.h"

// FUNCTION PROFORMAS

void clearLCD();		//Clear LCD display
void LCDNum();			//Output 5-digit revCount number to LCD
void Interrupt();		//Interrupt handler


//Time delay
void waitTime(unsigned int time);


//MAIN
//

void main ()
{

//Initialise Port A

 TRISA=0x17;			//Set all bits of Port A to input
  
// Initialize the LCD with startup message

 waitTime(1000);		//Wait a bit
 LCD(-2);			//2-line display, 8-bit, 5x7 format
 clearLCD();			//Initialize & clear screen
 LCDPrintAt(0,0);		//2nd message
 LCDString("RevMaster");	//Hello to the world
 LCDPrintAt(0,1);		//2nd line
 LCDString (VersionString1);	//Display software version
 waitTime(32767);		//Wait some more
 LCDPrintAt(0,1);		//2nd line
 LCDString (VersionString2);	//Display software date
 waitTime(32767);		//Wait some more
 
 LCDPrintAt(0,1);		//2nd line
 zeros=5;			//assume 1ppr and therefore 1 trailing zero
 scale=6;			//...and scale result by 6
 if (PA.B0==0)
 {
  LCDString("06");		//6 marks per rev
  zeros=5;			//...therefore 1 trailing zero
  scale=1;			//...and scale by 1
 }
 else if (PA.B1==0)
 {
  LCDString("60");		//60 marks per rev
  zeros=6;			//...therefore 0 trailing zeros
  scale=1;			//...and scale by 1
 }
 else LCDString("00");		//60 marks per rev
 LCDString(" PPR    ");		//
 waitTime(32767);		//Wait a bit
 
 LCDPrintAt(0,1);		//2nd message
 LCDString("     0 RPM");	//assume 1 mark per rev
 LCD(0x104);			//Force reverse cursor for number printing
 
//Initialise Port B and Interrupt settings

 TRISB=0x01;			//Set bits 1 to 7 of Port B to output,
 				//bit 0 to input
 OPTION_REG=0x85;		//Pull ups on B, TMR0 internal, 64 prescale
 INTCON|=(1<<T0IE)|(1<<GIE)|(1<<INTE);
 				//Enable interrupts for TMR0 & INTE
 
// MAIN CONTROL LOOP - Select major mode & execute that mode's behaviour
 
 while(1)			//Loop forever
 {
  if (timeInt)			//If there has been a 1/10th second interrupt
  {
   timeInt=0;			//Clear the int flag
   actual=countHi;
   actual=(actual<<8)+countLo;
   				//Get the count value
   countLo=0;			//Clear the count value
   countHi=0;
   actual=actual*scale;		//Scale the value by 1 or 6
   LCDNum();			//Print the value
   LCDPrintAt(16,1);		//Lose the cursor
  }
 }
};




//
// Waittime function - waits for a specified delay period.
//

void waitTime(unsigned int time)
{
 while(time--)	;		//Repeat loop time times
};

//
// LCD Clear function
//

void clearLCD()
{
 LCD(0x108);			//Display off
 LCD(0x101);			//Clear display, cursor home
 LCD(0x10f);			//Display on, cursor on, flash cursor
 LCD(0x180);			//Print position 0,0
};

//
// LCDNum function - prints 4 digit revCount to LCD display (backwards)
// Includes decimal point if the point parameter is within range of digits
//

void LCDNum()
{
 char digits;
 LCD((int)zeros-1+0x180+0x40);	//Print position zeros,0
 for(digits=5; digits; digits--)
 {
  LCD((actual%10)+'0');		//Print Nth digit 
  actual/=10;			//lose Nth digit
 }
};

//
//Interrupt handler
//Interrupt generated every 1/50 secs by timer 0
//and every time a pulse is detected on Port B bit 0
//

const int QuickInt=1;		// Flag use of quick interrupts

void Interrupt()
{
 #asm
 btfss INTCON,INTF		; If tacho interrupt...
 goto noTach
 incfsz countLo			; Increment low count
 goto clearTach
 incf countHi			; Increment high count if necessary
clearTach:
 bcf INTCON,INTF		; Clear tacho interrupt...
noTach:
 btfss INTCON,T0IF		; If timer interrupt...
 goto noTimer
 decfsz sec			; Decrement seconds count
 goto clearTimer
 movlw 1
 movwf timeInt			; Signal a timer interrupt
 movlw 50
 movwf sec			; Re-prime the timer
clearTimer:
 bcf INTCON,T0IF		; Clear timer interrupt...
noTimer:
 #asmend
}