/*
 *
 *  DOORKING TRANSMITTER CLONE v1.0
 *
 * This code will duplicate the digital output sequence for doorking transmitters
 * http://www.pagemac.com/azure/doorking.php
 *
 * Uses PIC12F629
 *
 * Made by Daniel Smith and Kevin Martin, 2012
 *
 */


#include "pic.h"
#include <pic12f629.h>
#include <xc.h>

  //__CONFIG(INTIO & WDTDIS & PWRTEN & MCLREN & BORDIS & UNPROTECT);  // for MCC18
  __CONFIG(FOSC_INTRCIO & WDTE_OFF & PWRTE_OFF & MCLRE_ON & BOREN_OFF & CP_OFF & CPD_OFF);  // for XC8

volatile char intflag;

// output a baseband bit
void outputbit(char in)
{
  // set timer for ~1ms
  TMR1H=0xfc;
  TMR1L=0x67;       //fc69
  intflag=0;
  GPIO5=in;     // set output pin
  T1CON=0x01;   //enable timer
  while (!intflag) ;
  T1CON=0x00;   //disable timer

  // set timer for ~2ms
  TMR1H=0xf8;
  TMR1L=0x75;   // f877
  intflag=0;
  GPIO5=0;      // clear output pin
  T1CON=0x01;   //enable timer
  while (!intflag) ;
  T1CON=0x00;   //disable timer
}

int main(void) {

  // configure the facility code and serial number here
  unsigned char fc=5;
  unsigned short sn=5555;
  unsigned char cbit;

  // set up the device
  TRISIO2=0;
  TRISIO4=1;
  TRISIO5=0;
  WPU=0;
  T1CON=0x00;
  INTCON=0xc8;      // enable IoC and timer interrupts
  IOCbits.IOCB4=1;  // enable interrupt on change for GPIO4 (button)
  GPIE=1;
  TMR1IE=1;


  while (1) {
    unsigned char outbyte;
    

     // check if button is pressed (active low)
    if (GPIO4) 
    {
      // button not pressed
      GPIO2=0;    //turn off led
      SLEEP();    // sleep to save power
      NOP();
      NOP();
      NOP();
    } 
    else    // button is pressed
    {
      GPIO2=1;    // turn on led

      // the output sequence is 24 manchester-encoded bits
      // the sequence has a start bit (1), 6 bit facility code, 14 bit serial num, and stop sequence (101)
      // a manchester 0 is 10, a manchester 1 is 01
      // data is sent MSB first
      
      // start bit
      outputbit(1);
      
      // facility code: 6 bits
      outbyte=fc<<2;
      for (cbit=6; cbit; cbit--) {
        if (outbyte & 0x80) {
          outputbit(0);
          outputbit(1);
        } else {
          outputbit(1);
          outputbit(0);
        }
        outbyte<<=1;
      }

      // serial number: 14 bits
      outbyte=sn>>6;
      for (cbit=8; cbit; cbit--) {
        if (outbyte & 0x80) {
          outputbit(0);
          outputbit(1);
        } else {
          outputbit(1);
          outputbit(0);
        }
        outbyte<<=1;
      }
      outbyte=(sn<<2)&0xff;
      for (cbit=6; cbit; cbit--) {
        if (outbyte & 0x80) {
          outputbit(0);
          outputbit(1);
        } else {
          outputbit(1);
          outputbit(0);
        }
        outbyte<<=1;
      }

      // stop sequence (manchester encoded: 010)
       outputbit(1);
       outputbit(0);

       outputbit(0);
       outputbit(1);

       outputbit(1);
       outputbit(0);


       // pause for 12ms (VERY IMPORTANT)
       // the gap between sequences is critical!
      TMR1H=0xd8;
      TMR1L=0x7d;       //fc69
      intflag=0;
      T1CON=0x01;   //enable timer
      while (!intflag) ;
      T1CON=0x00;   //disable timer
    }

  }
  
  return 0;
}

// interrupt vector
void interrupt isr(void) {
  if (TMR1IF) { // timer interrupt
    TMR1IF=0;
    intflag=1;
  }
  else if (GPIF) { // button press interrupt
    GPIO4;
    GPIO5 = 0;
    GPIF=0;
  }
}