#include <pic.h>
#include <string.h>
#include "delay.h"

__CONFIG(HS & WDTDIS & MCLREN & PWRTDIS & BORDIS & LVPDIS & UNPROTECT);

unsigned char rec_byte = '0';

void interrupt isr(void) @ 0x04
{
  unsigned char x;

  if(RCIF)            // serial rx interrupt?
  {
    if (OERR == 1)                              // overrun, reset UART
    { 
      CREN = 0;                                 // disable UART
      CREN = 1;                                 // re-enable UART
    }      
    else if (FERR == 1)                         // framing error (break?)
      x = RCREG;                                // read and discard byte
    rec_byte = RCREG;
  }
}

void init_pic16f628a()
{
  PORTA   = 0x00;    // Initialize PORTA
  PORTB   = 0x00;    // Initialize PORTB
  CMCON   = 0x07;    // comparators off
  TRISA   = 0x00;    // PORTA Outputs
  TRISB   = 0x00;    // PORTB Outputs
}

void init_usart(void)				
{

  TRISB  |= 0x02;               // Make RX pin an input  (RB1)
  TRISB  &= 0xFB;               // Make TX pin an output (RB2)
  SPBRG   = 129;			    // BaudRate=9600 @ 20Mhz as Table
                                // +0.16% error at this BaudRate

  // PIE1  : EEIE CMIE RCIE TXIE —--- CCP1IE TMR2IE TMR1IE	
  PIE1 = 0b00110000;            // replaces stuff below
  // TXIE    = 1;                  // enable serial tx interrupt
  // RCIE    = 1;                  // enable serial rx interrupt

  GIE     = 1;                  // enable global interrupts

  // TXSTA : CSRC TX9  TXEN SYNC —--- BRGH   TRMT   TX9D
  TXSTA=0b00100100;		        // Asynch,8bits,tx enb

  // RCSTA : SPEN RX9  SREN CREN ADEN FERR   OERR   RX9D
  RCSTA=0b10010000;		        // Cont receive enb	
} 

// send a single char
void usart_write_char(unsigned char ucChar)				
{	
	TXREG = ucChar;
	while(TRMT==0);		// Wait for TX to finish
}

void main()
{
  init_pic16f628a();
  init_usart();
  while(1)
  { 
	//while(!RCIF);	// Wait until data recieved
	//rec_byte=RCREG;	// Store for later

	usart_write_char(rec_byte);	// Transmit
    delay(200);
  }
}