Speed of operation and ease of use are primarily contained within the software component of the expansion card. The consumer must be satisfied with the interface and find it intuitive to use. At the same time, the software (both application and device) should be streamlined to increase efficiency and speed of operation. Both of these parameters affect the most critical aspect of the design (other than the accuracy of the GPS, which is out of our control), the battery life.

Our expansion module will draw power from both the Visor and its own onboard battery. Because the Visor is a PDA meant for portability and lasting battery life, our design must be efficient enough that the Visor’s batteries stay in tact for approximately the same amount of time as for Visor usage without our expansion module. Handspring claims that “normal use” will result in its 4 AAA batteries lasting “one month.” Though these are unspecific guidelines, and the exact battery life is different for different users, our target battery life should compete with this number. As we determine the exact GPS we will use, more information on battery life should be known.

Schedule

There are three components of the project, each intertwining with the other two:

Software – will be handled by Paul Niemczyk. This includes both the application software and the device drivers to control the expansion module and the receiver CPU.
Handspring expansion module – The interface will be handled by David Marshall. This includes designing the ROM that the Handspring will read for data about the expansion card (for plug & play and software purposes) and integrating serial to parallel data conversion.
GPS CPU – The CPU on the GPS receiver needs to be programmed to deliver the proper information, with the correct timing, to the expansion module when the Visor requests the information. The system level code and timing will handled by Tim Wilson

An approximate schedule will be (based on ten weeks available, starting the week of Sunday, February 13, 2000):

Week # Description 1 Cost analysis of components. Buy GPS receiver, serial-parallel converter, obtain software upgrades for Visor API development (available within one week). 2 Study of hardware specs for GPS, Handspring, software. 3 Timing diagram for communication between GPS, Visor, module hardware 4 ROM design, GPS to module hardware wired, driver software for GPS to module communication. 5 Bi-directional communication between expansion module and Visor, driver software for this communication (two weeks). 6 Send out ROM and expansion board design for manufacturing (two weeks) 7 Final device drivers written. 8 (Manufactured ROM received). Application software written. 9 Application software and testing of module. 10 Application software completed, testing completed, final report written 11 Project demonstrations.

Parts

Motorola Encore SL GPS receiver board$45

Motorola 4 bit Serial-parallel converter (2 of them)$9 (x2)

ROM processing, module manufacturing$~55

PCMCIA converter (for easy wiring to breadboard)$4

Motorola GPS antenna (may not be required)$~18

Parts Cost:$140

Labor

(100 anticipated hours/partner) X (3 partners) X ($50/hour) X (2.5)

Labor Cost:$37,500

Total Cost

Total Cost = Parts + LaborTotal:$37,640


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