Specifications

46
Fig. 4.4: Custom LCD glass art generated for this project.
could not be upgraded.
Character displays come in many sizes and the contents of the display are incredibly
flexible. Four lines by twenty characters is the size of display that is of interest. It is big
enough to be informative and small enough to be comparable in price to custom glass. It
does, however, require 5VDC and 2.5mA to operate. Although the character display uses
more power, the flexibility of the display was desired. The TM204JAA7 [49] was the exact
part selected.
4.2 Construction
The construction of the designated alpha test units commenced May 2007. The alpha
units’ purpose was to verify the function of all hardware features and to build up the basic
device drivers and rudimentary OS. Only six devices were constructed. Details of the testing
and verification will be discussed in section 5.1. The alpha tests resulted in some changes
in the design and layout of the board. These changes were minor en ough to move to the
beta phase of testing. T his phase required the production of 75 units. During beta testing,
all features were to be implemented and tested. Further, 60 of these units were shipped to
a few producers and other interested parties for evaluation.