Specifications

80
Seen below is Figure 3.2.1-5, a diagram of the hand held unit I²C bus. In this
diagram, the Microcontroller will act as the bus master, driving the SCL line with
a clock frequency set as a function of the desired transaction speed mode, and
will both drive and sample the SDA line to send display data to the LCD display
device, as well as read the digital output from the differential pressure sensor
ADC.
Figure 3.2.1-5 Hand Held Unit I²C Bus Diagram
3.2.2 Wireless
The target development board is equipped with a Texas Instruments CC2500
2.4Ghz wireless transceiver chip, providing a physical layer to implement
wireless communications with other devices. Also provided by Texas Instruments
is a low power, proprietary wireless communications stack called SimpliciTI. This
software stack occupies a small segment of program flash memory (<8KB), while
providing a broad range of configuration options for the network topology,
including peer-to-peer, access-point based packet routing, and packet repeater
relay.
The provided SimplciTI software defines a basic application programming
interface that establishes functions for data send and receive, ping, device link
and initialization, and radio frequency selection. The software also provides a
way to define a persistent hardware address, so that communications with other
similar devices can be easily prevented. This will be the interface of choice for
passing status and authentication messages back and forth between the hand
held unit and the automobile control box.
3.2.3 Programming
Programming the MSP430 target board is accomplished via the provided USB
debugging interface. This interface provides a back channel MSP430 application