How to Use a PC's Parallel Port to Communicate with 2-Wire Devices

By: Brian Vasquez

Abstract: The purpose of this application note is to show how to build a quick, simple, and cheap 2-wire (I²C-compatible) interface using a PC's parallel port. This application note was specifically written for those who just received or just ordered Dallas Semiconductor device samples and realized that they now need a way to communicate with the 2-Wire devices. Although many solutions exist, the one presented here does not require a microcontroller, firmware, nor any difficult to procure ICs. To further aid in the task at hand, Windows® 95/98 software is provided to eliminate the headaches associated with the daunting task of trying to debug both hardware and software simultaneously. Being given the software, along with a couple debugging tools, all efforts can be applied solely to getting the hardware up andrunning as quick as possible.