[lug] Ethernet Enabled PLC/Linux Microcontroller
nate at natetech.com
Sat Aug 1 01:52:43 MDT 2009
On Jul 31, 2009, at 7:27 AM, Swavek Skret wrote:
> I need to control a hardware unit that does not have a standard
> interface (ethernet, RS-232, etc) but simply provides a binary
> voltage to flag that it functions correctly or not. I am considering
> using an ethernet enabled microcontroller with Linux OS ideally.
> If anyone has related experience and would like to share or
> recommend a particular hardware I would appreciate it.
Full blown embedded Linux is probably overkill. Any microcontroller
can be made to do simple voltage monitoring and spit out serial
information to a connected PC, phone line via a modem, whatever...
Microchip and Atmel are the most popular for "hobby" projects, and
there's thousands of designs available for commonly used ones on the
Both have free Assembly and C programming language support, but you do
have to learn a bit about how to program "at the hardware level", so
to speak. A month or two of study will yield a lifetime of cheap,
virtually bullet-proof hardware control solutions.
There are also development kits for both major chipsets that make
programming them a breeze in languages like BASIC and similar. Even
some GNU/GCC projects for both, if you're willing to put up with the
usual crappy open-source documentation and brain-damage.
The forums at Microchip.com or avrfreaks.net are good starting points,
if you already know basic electronics including Ohm's law and how to
solder, both of which are pretty basic -- and there's plenty of "DIY"
ways to learn both on the Net.
There's no need to use an entire OS like Linux, when a few lines of C
code compiled into machine language by a free compiler and dumped into
a chip will do the job. The logic involved is basically 1 for on, 0
for off... something we all know, and the electronics involved in
seeing if a device is "on or off" is not much more difficult than the
circuit for a typical table lamp.
Going all the way to Linux on a chip will be more "fun", but WAY more
expensive both in the short and long term, unless you're only doing
ONE of these. I do suggest hunting the web for microcontroller
circuits to do such a thing.
Other "medium difficulty" options might be to use something like a
PicAXE or Arudino where a hardware engineer has already developed the
board, the layout, defined the chip(s) needed and provided a
rudimentary real-time "OS" FAR better suited than Linux to handling
the little (inexpensive) chipsets.
Etc etc... the possibilities are endless. But Linux on the chip
certainly sounds like SERIOUS overkill when a single chip can do the
nate at natetech.com
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