#include <xc.h>
#include <string.h>
#include <stdio.h>
#include <htc.h>

#define _XTAL_FREQ   20000000

void InitUART(void);
void SendByteSerially(unsigned char Byte);
unsigned char ReceiveByteSerially(void);
void SendStringSerially(const unsigned char* st);


void main()
{

    GIE  = 1;                           // Enable global interrupts
    PEIE = 1;                           // Enable Peripheral Interrupts


    InitUART();
    TRISA = 0x00;
    PORTA = 0x00;

    while(1)
    {




    }
}


void interrupt ISR(void)
{
    if(RCIF)  // If UART Rx Interrupt
    {
        if(OERR) // If over run error, then reset the receiver
        {
            CREN = 0;
            CREN = 1;
        }

        SendByteSerially(RCREG);    // Echo back received char
    }
}

void InitUART(void)
{
    TRISC6 = 1;                     // TX Pin
    TRISC7 = 1;                     // RX Pin

    SPBRG = ((_XTAL_FREQ/16)/9600) - 1;
    BRGH  = 1;                      // Fast baudrate
    SYNC  = 0;                      // Asynchronous
    SPEN  = 1;                      // Enable serial port pins
    CREN  = 1;                      // Enable reception
    SREN  = 0;                      // No effect
    TXIE  = 0;                      // Disable tx interrupts
    RCIE  = 1;                      // Enable rx interrupts
    TX9   = 0;                      // 8-bit transmission
    RX9   = 0;                      // 8-bit reception
    TXEN  = 0;                      // Reset transmitter
    TXEN  = 1;                      // Enable the transmitter
}


void SendByteSerially(unsigned char Byte)  // Writes a character to the serial port
{
    while(!TXIF);  // wait for previous transmission to finish
    TXREG = Byte;
}

unsigned char ReceiveByteSerially(void)   // Reads a character from the serial port
{
    if(OERR) // If over run error, then reset the receiver
    {
        CREN = 0;
        CREN = 1;
    }

    while(!RCIF);  // Wait for transmission to receive

    return RCREG;
}

void SendStringSerially(const unsigned char* st)
{
    while(*st)
        SendByteSerially(*st++);
}