It depends on the embedded application. Have a specific question?

The Inline::C module may be useful to you, for embedding C in Perl
(which admittedly wasn't your question, but it's a start):

<http://search.cpan.org/~ingy/Inline/C/C.pod>
<http://inline.perl.org/inline/home.html>

If the Inline::* framework doesn't help you, then the other main
approach is writing XS code for integrating Perl and C. Note though that
XS can be complicated stuff, and it's a very popular topic to avoid. The
perlxs and perlxstut perldoc pages may be a good place to start here:

<http://perldoc.perl.org/perlxs.html>
<http://perldoc.perl.org/perlxstut.html>

This is highly dependant on the operating system you're using.

Most POSIX-y systems (Linux, OSX, Solaris, etc) will provide serial port
access with a virtual file under /dev, but this approach won't do you
any good at all on Windows. In that case, Win32::SerialPort may be the
way to go.

<http://search.cpan.org/~bbirth/Win32-SerialPort-0.19/lib/Win32/SerialPort.pm>

But if you aren't on Windows, and you don't care to interact with the
virtual /dev device-file directly, then your best bet -- actually, your
best bet for many of these questions -- is to search CPAN.

<http://search.cpan.org/search?query=serial+port&mode=all>

Among the hits that that turns up are two near the top that look useful
for you: RFID::Matrics::Reader::Serial & RFID::Alien::Reader::Serial

<http://search.cpan.org/author/GIFF/RFID-Matrics-0.002/lib/RFID/Matrics/Reader/Serial.pm>
<http://search.cpan.org/author/GIFF/RFID-Alien-0.002/lib/RFID/Alien/Reader/Serial.pm>

And that, in turn, suggests that there may be RFID modules that exactly
address your problem. Try searching for them to see:

<http://search.cpan.org/search?query=rfid&mode=all>

Many, many hits turn up. Look them over and see which will work for you.

I'm not sure what you mean by "embedded" here. I know what an embedded
system is, but I don't know what constraints your embedded system has
that might make it uniquely different from other systems.

I suspect your better bet is to look for reference materials that deal
with the specific type of problem you're trying to solve -- serial
programming, network programming, etc -- and then see how the solutions
you find in such reference sources can be applied to your situation.

That said, for a problem domain like networking, which this can be seen
as an example of, the best book is probably Lincoln Stein's _Network
Programming with Perl_:

<http://www.modperl.com/perl_networking/>
<http://www.amazon.com/exec/obidos/tg/detail/-/>

But you may feel that this is tangental to the specific work you're
doing. It's worth a look to see if it helps, but if you need something
else, you may want to poke around <http://books.perl.org/> to see if
anything there comes closer to the mark.



--
Chris Devers