/* Exercise 8.3 Reaction Timer */
/* Created David Miles April 2006 */
/* Updated Ben Rowland Febuary 2014 */

#include <xc.h>

// CONFIG1
#pragma config FOSC = HS        // Oscillator Selection (HS Oscillator, High-speed crystal/resonator connected between OSC1 and OSC2 pins)
#pragma config WDTE = OFF       // Watchdog Timer Enable (WDT disabled)
#pragma config PWRTE = OFF      // Power-up Timer Enable (PWRT disabled)
#pragma config MCLRE = ON       // MCLR Pin Function Select (MCLR/VPP pin function is MCLR)
#pragma config CP = OFF         // Flash Program Memory Code Protection (Program memory code protection is disabled)
#pragma config CPD = OFF        // Data Memory Code Protection (Data memory code protection is disabled)
#pragma config BOREN = ON       // Brown-out Reset Enable (Brown-out Reset enabled)
#pragma config CLKOUTEN = OFF   // Clock Out Enable (CLKOUT function is disabled. I/O or oscillator function on the CLKOUT pin)
#pragma config IESO = OFF       // Internal/External Switchover (Internal/External Switchover mode is disabled)
#pragma config FCMEN = OFF      // Fail-Safe Clock Monitor Enable (Fail-Safe Clock Monitor is disabled)

// CONFIG2
#pragma config WRT = OFF        // Flash Memory Self-Write Protection (Write protection off)
#pragma config VCAPEN = OFF     // Voltage Regulator Capacitor Enable (All VCAP pin functionality is disabled)
#pragma config PLLEN = OFF      // PLL Enable (4x PLL disabled)
#pragma config STVREN = ON      // Stack Overflow/Underflow Reset Enable (Stack Overflow or Underflow will cause a Reset)
#pragma config BORV = LO        // Brown-out Reset Voltage Selection (Brown-out Reset Voltage (Vbor), low trip point selected.)
#pragma config LVP = OFF        // Low-Voltage Programming Enable (High-voltage on MCLR/VPP must be used for programming)

#define _XTAL_FREQ 19660800	// Defines the hardware crystal frequency allowing the delay function to work correctly

#define SPEED 500               // Used to trim the delay loops

#include "lcdlib.h"

const unsigned char banner1 [14] = {'R','e','a','c','t','i','o','n',' ','G','a','m','e',0x00};
const unsigned char banner2 [14] = {'*','*','*','*','*','*','*','*',' ','*','*','*','*',0x00};
const unsigned char start1 [] = {'P','r','e','s','s',' ','t','h','e',0x00};
const unsigned char start2 [] = {'b','u','t','t','t','o','n',' ','t','o',' ','s','t','a','r','t',0x00};
const unsigned char ready [] = {'R','e','a','d','y','.','.',0x00};
const unsigned char score [] = {'Y','o','u',' ','s','c','o','r','e','d',' ',0x00};

int time_count = 0 ;
unsigned char timer_active = 0 ;
unsigned char counter = 0;


void setup_hardware (void)
{
    ANSELA = 0x00;              //Set PortA to use digital inputs
    ANSELB = 0x00;
    TRISA = 0x01;               //PORTA bit 0 set to input, other pins set to outputs
    TRISB = 0x00;               //PORTB set to all outputs

    INTCON = 0b10100000;        //Configure the INTCON register to enable timer interrupts
    OPTION_REG = 0b01000100 ;   //Configure the timer to use the prescaler
}


//returns the debounced state of the bottom bit of PORTA
unsigned char key ( void )
{
    unsigned char count = 0;
    unsigned char oldv, newv;

    oldv = PORTA & 1 ;
    while ( count < 20 )
    {
        newv = PORTA & 1 ;
        if ( oldv == newv )
        {
            count++ ;
        }
        else
        {
            count = 0 ;
            oldv = newv ;
        }
    }
    return oldv ;
}


//repeatedly calls key until it is down
void keywait ( void )
{
    while ( key() == 0 );
}


//repeatedly calls key until it is up
void upwait ( void )
{
    while ( key() == 0 );
}


void tmrHandler( void )
{
    if (timer_active != 0)          //increment the timer if it has been set to active
    {
        time_count = time_count + 1 ;
    }
}


//This is the interrupt handler It is called when the PICmicro detects an interrupt.
//It checks the status bits to find out who caused the interrupt and then calls that handler
void interrupt isr( void )
{
    if(INTCON & 0b00000100)         //if the timer has overflowed bit 2 of INTCON is set high
    {
        INTCON = INTCON & 0b11111011;          //clear the bit to turn off this interrupt
        counter = counter + 1;
        if ( counter > 2 )
        {
            counter = 0;
            tmrHandler();           //call the handler  function
        }
    }
}


void big_delay ( int size )
{
    int i, j;
    for (i = 0; i < size; i = i + 1)
    {
        for (j = 0; j < SPEED; j = j + 1);
    }
}


void display_value ( int value )
{
  unsigned char hunds, tens, units ;

  /*  first get the digits  */

  units = value % 10 ;
  value = value / 10 ;
  tens = value % 10 ;
  value = value / 10 ;
  hunds = value % 10 ;

  /*  now display them      */

  lcd_print_ch ( '0' + hunds ) ;
  lcd_print_ch ( '0' + tens ) ;
  lcd_print_ch ( '0' + units ) ;
}



int main (void)
{
    setup_hardware();
    lcd_start();

    lcd_cursor (0, 0);
    lcd_print (banner1);
    lcd_cursor (0, 1);
    lcd_print (banner2);
    big_delay (1000);

    while (1)                   //Loop forever
    {
        lcd_clear ();           //turn off LEDS
        PORTA = 0x00;

        lcd_print(start1);      //display the start message
        lcd_cursor(0, 1);
        lcd_print(start2);

        keywait();              //wait for keypress
        lcd_clear();
        big_delay(2000);

        PORTA = 0x1e;           //light the LEDS
        time_count = 0;         //clear the counter
        timer_active = 1;       //start it running
        keywait ();             //wait for the button
        timer_active = 0;       //stop the timer
        lcd_clear ();

        display_value ( time_count );
        keywait ();
    }

    return 0;
}