Specifications

brownout reset and low voltage detect circuits. Therefore, allowing the user to

assert what happens when a circuit is in low voltage mode. The PIC18F has

many different advantages but would be overkill as a microcontroller from a stand

not quite enough for the design needed to perform the task needed.

2.2.3.2 Texas Instruments MSP430

The MSP430 series of microcontrollers by TI are recognized industry-wide as

being an ideal platform for any kind of embedded or sensor network design. They

are based on a low-power, 16-bit RISC microprocessor design, and carry a

feature rich set of characteristics ideal for a wide range of design purposes. A list

of features is as follows.

Low voltage power supply requirements (1.8 VDC – 3.6 VDC)

Internal clock frequency up to 16MHz

Universal Serial Interface, configurable as either I2C, SPI, or UART for

RS232 serial communications

Available Analog-to-Digital converters with 10/12/16 bits of resolution

Two 16-bit timers

Low power modes provide minimal power draw in standby, as little as

700nA

Another very appealing feature of the MSP430 is the availability of inexpensive,

easily configurable development boards that can actually be inserted into a real

design, and allow for easy programming and debug from any PC with USB. The

EZ430 development kits also come in a variety of flavors, offering MSP430

microcontrollers with a variety of features, including one that offers an integrated

2.4GHz transceiver for wireless communications with other similarly configured

boards.

Figure 2.2.3.2-1 shows how the small board containing the digital I/O lines,

wireless communications hardware, and the microcontroller, can be easily

removed from the USB Debug module, and placed directly into our design. The

EZ430-RF2500 variant would simplify our design by offering a wireless

communications interface between the portable breathalyzer unit and the

automobile control box. This would reduce the amount of physical design

necessary, as we would no longer require a physical connection between the

units for the purposes of communication. A turnkey wireless solution would also

serve to reduce the time spent in hardware communications debug, since the

wireless transceiver and chip antenna have already been tested and validated by

Texas Instruments upon arrival. Also available with this development kit is a

battery board that allows for an easy mobile power implementation, before a