Sequence Diagrams are associated more with UML and object oriented
design than embedded software design. But UML sequence diagrams are very useful
for describing system behavior over time. They also help us understand how the
system interacts with its environment. The sequence diagram basically shows
system actions based on fixed inputs over a given time line.
There are three elements to consider when creating a sequence diagram example.
1. The objects or libraries used in the sequence of events placed horizontally
in a row across the top
2. The life line which is a dashed line that drops down vertically from each
3. The events that occur in sequence as we go down the lifeline
Sequence diagrams are ideal for remote communications projects using modems
because each step in the communications process can be described in sequence
over time. All the clutter of control structures and data structures is
removed, and we are left with a very clear picture of the communications events
This concept can be applied to almost any peripheral especially when a human
interface is involved.
Although we keep the design methodology close at hand when think about our
programs, we do not always design and document a sequence diagram for you
unless requested. As mentioned before there are several advantages to having
your documentation on hand:
· You have a better idea about what your program does without trying to figure
it out from code
· You can clearly explain to your next programmer, who may be your employee
what exactly was done
· You can leverage documentation to your end user which describes the device
It is best to request a documentation package during initial stages of the
project, while we are working on the elements of the project that need to be
documented. It will take twice as long to go back and correctly document what
has been done in the past.