Specifications
65
There were some other LCD screens we as a group were looking into. One if the main
design issues we ran across when making our decision for the LCD was: Did we want to
use a alpha numeric display or did we want to use just a simple 7 segment display? We
decided on using the alphanumeric display because unlike the 7-segment display we
can display characters, which would be a great feature for our users because they
would not have to try to figure out what this number means on the screen. Instead it will
show up as a short phrase and then tell the user the number or value associated with
that phrase. We completely ruled out a display using moving characters and motion
picture because it would be very nice to have but it would outweigh the benefits of using
this type of device. First of all it draws more power, which we wanted to keep at a
minimum. Also, dimensions of the screen would not be ideal for displaying a message.
We were looking for something rectangular, which we can fit complete thoughts on.
Most of the motion displays were square, which showed the messages more awkward
and was not user friendly. In the end we decided because of these design issues to go
with the alphanumeric displays. It is a very simple display and I think that it would be a
great design to use in with our display.
5.6 Microcontroller
From our research, our group has decided that the line of microcontrollers most suitable
for our project would be the MSP430 line of microcontrollers from Texas Instruments.
The C programming language, which all of our group members are familiar with, will be
used to write all of the code to program the microcontroller. The power supply for the
microcontroller will come from the 5 VDC USB connections from our power inverter
output.
Some of the distinguishing features of the MSP430 line that will work well with our
design are its low power consumption and its ability to respond quickly when in use. All
of the microcontrollers from MSP430, while not in use, will go into a stand-by mode that
draws virtually no power from the battery. When the microcontroller does need to be
used, it has a response time of less than a microsecond, making the real time
responses that it needs to make more accurate. These aspects of the MSP430
microcontrollers are depicted in the image below.
Figure 53 – MSP430 Mpower Consumption
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