The programmable DC motor controller with LCD project presented in Chapter 2, Programmable DC Motor Controller with LCD, is an example of a low design version of a Human Machine Interface (HMI). An HMI allows a human operator to operate a robot or intelligent machine using a control panel. The operator interacts with the DC motor HMI using a pair of electrical slide switches to turn the electromechanical machine on or off. The LCD provides a visual display of the DC motor's operating states of on or off. The disadvantage to an electromechanical-based HMI device is the mechanical wear of the electrical slide switch contacts. Deterioration of the slide switch contacts will not allow proper signal level detection (+5V or 0V) by the Arduino to operate the DC motor correctly. A solution to this problem is to use a software-based HMI design. An example of a software-based HMI design is shown in the following screenshot. In this example of HMI design, the electromechanical...