//////////////////////////////////////////////////////////////////////////
////                        Dallas Touch Driver                       ////
////                                                                  ////
////  present = touch_present()   Issues a reset and returns TRUE     ////
////                              if the touch device is there.       ////
////                                                                  ////
////  data = touch_read_byte()    Reads one byte from a touch device. ////
////                                                                  ////
////  ok = touch_write_byte(data) Writes one byte to a touch device   ////
////                              and returns TRUE if all went OK.    ////
////                              A FALSE indicates a collision with  ////
////                              another device.                     ////
////                                                                  ////
//////////////////////////////////////////////////////////////////////////
////        (C) Copyright 1996,1997 Custom Computer Services            ////
//// This source code may only be used by licensed users of the CCS C   ////
//// compiler.  This source code may only be distributed to other       ////
//// licensed users of the CCS C compiler.  No other use, reproduction  ////
//// or distribution is permitted without written permission.           ////
//// Derivative programs created using this software in object code     ////
//// form are not restricted in any way.                                ////
////////////////////////////////////////////////////////////////////////////

#ifndef TOUCH_PIN

#define TOUCH_PIN  PIN_B0
#bit    TOUCH_PIN_BIT = 6.0 

#endif


byte touch_read_byte() {
   byte i,data;

   for(i=1;i<=8;++i) {
     output_low(TOUCH_PIN);
     delay_us(14);
     output_float(TOUCH_PIN);
     delay_us(5);
     shift_right(&data,1,input(TOUCH_PIN));
     delay_us(100);
   }
   return(data);
}

byte touch_write_byte(byte data) {
   byte i;

   for(i=1;i<=8;++i) {
     output_low(TOUCH_PIN);
     delay_us(10);
     if(shift_right(&data,1,0)) {
       output_high(TOUCH_PIN);
       if(!TOUCH_PIN_BIT)
         return(0);
     } else {
       output_low(TOUCH_PIN);
       if(TOUCH_PIN_BIT)
         return(0);
     }
     delay_us(50);
     output_high(TOUCH_PIN);
     delay_us(50);
   }
   return(TRUE);
}

byte touch_present() {
    boolean present;

    output_low(TOUCH_PIN);
    delay_us(500);
    output_float(TOUCH_PIN);
    if(!input(TOUCH_PIN))
      return(FALSE);
    delay_us(65);
    present=!input(TOUCH_PIN);
    delay_us(240);
    if(present)
      return(TRUE);
    else
      return(FALSE);
}