// Dallas 1-wire 16-bit CRC calculation. Developed from Maxim Application Note 27.
uint16_t crc16( uint8_t *data, uint8_t len)
{
      uint16_t crc=0;
      
      for (uint8_t i=0; i<len;i++) 
      {
            uint8_t inbyte = data[i];
            for (uint8_t j=0;j<8;j++) 
            {
                  uint8_t mix = (byte(crc)^ inbyte) & 0x01;
                  crc = crc >> 1;
                  if (mix) 
                        crc = crc ^ 0xA001;
                  
                  inbyte = inbyte >> 1;
            }
      }
      return crc;
}