Integrating physical devices with IOTA — Adding a user interface

The third part in a series of beginner tutorials on integrating physical devices with the IOTA protocol.

Introduction

This is the third part in a series of beginner tutorials on integrating physical devices with the IOTA protocol. In this tutorial we will be using an Liquid Crystal Display (LCD) to provide a simple Graphical User Interface (GUI) for our IOTA payment system.

If you haven’t read the first tutorial in this series, you should read it before continuing as it forms the foundation for the project we are building on in this tutorial.

The Use Case

Now that we have our new IOTA powered refrigerator payment system up and running as described in the first tutorial, we should take a step back and look at any improvements that could be made to our system. If we look at it from the user (hotel guest) point of view, one problem that stand out is that there is no indicator telling him the current status of his refrigerator service, and thereby no indication as to if or when he needs to add additional funds in case he wants to prolong the service. We also have some issues related to the printed QR Code. In case the hotel owners wants to change the IOTA payment address for one or more refrigerators he would have to physically replace the printed QR code for each refrigerator in his hotel. Another problem related to the printed QR code is that a bad actor in theory could replace the official printed QR code with a fake QR code, sending any future refrigerator payments to the wrong address. We also have and issue related to managing the price of the refrigerator service. How can the hotel owner display an up-to-date price of his refrigerator service with respect to the volatile IOTA market price? A logical solution to these problems would be to provide the guest