Jean-Marc Beaune wrote:
I tried several times to start with embedded linux but can't really
figure out how to start in a proper way.
It's really quite simple.
Choose a simple problem to solve that requires an embedded system.
Running a large database and sending out packets, is not a valid
reason. Why? Because you can use a server for that purpose.
Now minimizing that server to fit into an airplane, so it is
as light-weight and low power as possible, is a valid reason
to build an embedded system.
Choose an OS (embedded linux cause it's the coolest and has too many
readily available software resources).
Embedded linux is not the same thing as embedded (gentoo) linux!
Caveat Emptor!
Take one sheet of paper and specific the hardware resources you
need to solve that problem:
Micro controller (decision making capability based on software)
A/D analog (input/output) digital converters ?
DIO digital input/output
usb
special sensors such as temperature, pressure, acceleration.....
flash
amount/types of memory
ethernet (or 2)
etc etc
(you make the list)
Folks on this list will help you with identifying and
solving your problem.
Choose a processor/arch that readily solves your design constraints
but has enough computation resources to run embedded linux
and to solve your problem, too.
Here is where you ask the list for architecture recommendations
for example. If your problem requires low power, so as to
run off of batteries or a solar panel, then that will
affect your selection of processor. Different processors
use vastly different amounts of energy. Low power is but
one dimension of processor selection.
If you just want to noodle in the office, you may want to
choose a processor that comes on a SBC (single board
computer) such as mini-itx form factor or one of the epia
boards and an x86 arch, so it is closest to what you want,
and most familiar (arch) to what you have used.
You can look at the various arch's supported by gentoo embedded,
as that will quickly 'skinny down' your selection.
You can even visit various vendor web sites to look through
a myriad of boards (SBC) that the various vendors offer.
Then ask on this list to see what others have done, so you
can leverage their knowledge and get a SBC (embedded gentoo linux
board) that is familiar to persons on this list. That way
help is easy to find.
Maybe you should start by reading the list archives to see
what other (embedded) noobs have chosen to begin their
quest?
Alternatively, maybe GNAP is ready for noobs to once again build a
simple firewall on an old x(4)86 box as their first exposure to
embedded (gentoo) linux. Make sure there is a 'body of work'
within embedded gentoo for the processor/SBC you choose,
if you want the least painful path towards your quest(goal)
of solving the problem you defined above. A firewall is a nice
project, because it's very likely to be something that you
use and maintain. Choose your problem, wisely. GNAP is a very
inexpensive introduction to embedded gentoo, as most folks
have old pc hardware just laying around.
Building an embedded system that is part of an aimless wandering
experience, most often leads to failure and abandonment. If you
build something that you want and will use to solve a problem, then
you will be hooked and will be well on your way to becoming an
embedded systems develop, imho.
Embedded systems are spartan (hard and minimalistic) ventures that
are best employed to solve narrowly focused problems. That's the
justification for not using a server or workstation to solve
the same problem.
ymmv,
James
