Specifications

Two major problems arose during this phase. The ﬁrst bug showed itself during the

ﬁrst few days of testing. After operating for a full day or when an SD card was inserted

into the device, th e system would crash. An easy ﬁx for this is to trip the b attery reset

and the s ystem would start up again. But the system would then become sluggish and

non-responsive at times. After many attempts, the PC software retrieved the log ﬁle and

conﬁguration ﬁle from the device. The logs were replete with sensor measur ement errors.

The sensor causing the error was a previously un-conﬁgured digital port. However, looking

at the conﬁguration ﬁle it became apparent that the last quarter of the ﬁle had become

corrupted. The culprit was some of the new code that was causing the stack to overﬂow

into the neighboring conﬁguration ﬁle. This p roblem was ﬁxed by optimizing the stack

usage and adjusting the global variables declared to reﬂect a more space-wise emph asis.

The allowed stack size grew from 376 bytes to 516 bytes. This is enough to guarantee no

further problems with the stack.

The second problem that surfaced during this phase was that the application reached

the code space limit of the MCU. The ﬁnal code size came to 67K bytes with over 13,000

lines code. This means that the current platform has insuﬃcient memory for all of the

desired functions this product. The radio fu nctions and operation require about 10K bytes

more. For a short term resolution, the Data Manager will come with two possible ﬁrmware

applications. One supports all LCD screens and the other will support the radio. For long

term, a new microcontroller will need to be selected and a new platform redesigned around

this IC.

5.2.3 Phase Three

The ﬁnal stage of testing required the product to support all radio operations. This

included network personality changing, automatic mesh network creation and device s yn-

chronizations, computer-to-network pass through operations, and radio power management.

The novel ability to chan ge th e role of a particular network node is practically unattainable

for most ZigBee radio modu les. T his device contains images of the radio’s personalities

and re-ﬂashes the radio as necessary. When a network starts up , the radios automatically