/* Exercise 4.2 LED driver  */
/* 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


//A value for each bit in PORTA. We can feed in the number of the LED and it will give us the value to put into A
const unsigned char enable [4] = { 1, 2, 4, 8 } ;

//These are the patterns for the LEDs which were worked out from the datasheet.
//Note that to light a LED the bit on PORTB must be low I can use this array to convert from a digit to the 7 segments needed
const unsigned char patterns [10] = { 0xc0, 0xf9, 0xa4, 0xb0, 0x99, 0x92, 0x83, 0xf8, 0x80, 0x98 } ;
//                                      0     1     2     3     4     5     6     7     8     9


void setup_hardware (void)
{
    ANSELA = 0x00;              //Set PORTA to Digital Mode - Defaults to analogue mode
    ANSELB = 0x00;              //Set PORTB to Digital Mode - Defaults to analogue mode
    OPTION_REG = 0xC0;
    TRISA = 0xF0;               //Set bits 0-3 PORTA to be configured as an output
    TRISB = 0x00;               //Set all bits of PORTB to be configured as an output
}


//Performs a delay so we can hold the display for us to read it
void delay ( unsigned char size ) {
    unsigned char  i ;
    for ( i=0 ; i < size ; i= i + 1 ) ;
}


//This function takes two parameters, the value to be displayed and the number of the LED unit to use
void display ( unsigned char digit, unsigned char pos )
{
    LATB = patterns[digit];     //Set the pattern on the LED
    LATA = enable[pos];         //Turn on the required LED unit

    delay(10);
    LATA = 0;
}


int main (void)
{
    setup_hardware();

    while (1)                   //Loop forever
    {
        display(0, 0);          //Display the number 0 on segment 0
        display(1, 1);          //Display the number 1 on segment 1
        display(2, 2);          //Display the number 2 on segment 2
        display(3, 3);          //Display the number 3 on segment 3
    }

    return 0;
}