Specifications

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incorporate an LCD for use in portable electronics often have their own
microcontrollers integrated, for the purpose of receiving display update
messages from the system, and converting those messages into the electrical
signals that drive the display. Considering the additional integrated hardware
required to drive one of these displays, as well as the backlight for illumination,
an LCD will require much more power than any other electronic display suitable
for portable electronic devices. Due to the increased complexity of the display, as
well as the low demand for displays of a particular size and the combination of
factors that make each display unique, these are also the most expensive
displays that can be integrated into the design. The tradeoffs for the increased
complexity and power consumption are notable however, both for the developer
and the end user. LCD displays offer a perceived level of quality that cannot be
matched by competing technologies, presenting the feeling of a higher quality
product to the end user. Additionally, the integrated microcontroller element
allows for device communications on a standardized communications bus, using
an industry recognized protocol for device communications. This reduces the
need for additional driver hardware, as well as software configuration for status
messages being driven to the display. This also allows for the use of the display
in debugging, as the variety of messages that can be displayed allow for real-
time understanding of system status messages, machine-state indications, and
even measured data directly out of the system microcontroller. Such functionality
can be disabled for the end-user, but would provide an extremely useful utility
during the early stages of prototyping a design.
2.9.4 Display Conclusions
Based upon a thorough evaluation of available display technologies, the
conclusion of the design team is that a pre-built LCD module would be the most
effective addition to the overall system design. The combination of simplified
software development, increased perception of quality, versatility of display
readability in a variety of lighting environments, as well as the lack of a
requirement for additional driver hardware makes the LCD module a great
choice. While most handheld personal breathalyzer units make use of simple
seven-segment displays for communicating basic information with the end user,
the costs of mass production are not being factored into the design of our
prototype. As such, the increased per-unit cost of the LCD can be ignored for
prototyping and development purposes.
2.10 Alcohol Sensor
Without much explanations required, the alcohol sensor is the key component of
this unit and the project. Although different functionality and portability are always
desirable and are also understood that it is the easiest way to differentiate itself
to any other breathalyzer in the market. It still has a sole purpose of detecting the
blood alcohol content from a person who’s been intoxicated with alcohol and