Preliminary Design Report
9
User Interface
The user interface is the system through which the device communicates with the user,
prompting the user for input, receiving commands, and providing information about the
dispenser’s status. It consists of a keypad, barcode scanner, on/off switch, and LCD screen. The
level 2 block diagram for the user interface is show in Fig. 3.
Figure 3: Level 2 Functional Block Diagram for User Interface
