[Soekris] 2 [serial port/LCD] questions about the net4501

Chuck Yerkes chuck+soekris at 2004.snew.com
Thu Aug 12 20:45:33 UTC 2004

Quoting dan at dracosplace.com (dan at dracosplace.com):
> I'm new to the list and the whole embedded scene

Well, SBC (single board computer) rather than embedded in any sort
of classic or common sense.

> second thing is i'm looking to get my 4501 to connect to an lcd. I know the lcd
> will run by parasite off of the serial port, but its back light is powered by a
> 5v floppy drive connection.

Parasiting off the serial port(s) has been an issue as it doesn't provide
much power at all.  I've run power straight into (intercepted) serial
pins to work around that.

1) "The serial port" on the soekis is a serial CONSOLE port.
   (You don't want to use it for anything else unless you've got
    lots and lots of good reasons and can cope with the living heck
    - not quite hell - you'll be in for deviating)
2) On the 4501 and 4801, there is a second serial port.
   (on the 4521/4511 it's covered over by the PCMCIA stuff).
   On the 4501 it's holes on the board (looks like a DE-9 plug
   and will TAKE a DE-9, I use RJ45s for serial, so...)
   That is COM2 (however your OS maps that).

   On the 4801, it's available in a 10 pin header.

   Other headers on both contain the digital IO pins that the CPU
   can use (and aren't in use by the board).  The 4501 uses an Elan
   chip and lots of info is available on it and FreeBSD (and perhaps
   OpenBSD -current) have drivers to deal with them.

> The 4501 site says that it has an
> "Option for 5V supply using internal connector"
To provide regulated power to the computer.

Notable: there are several serial LCD devices.  My 1Wire weather
station (which the crystalfonz stuff uses) needs more power than
a USB serial provides.  Right now I've got to make "injector box"
that intercepts the pins that are unused except to power the serial
(RTS and DTD?  I forget offhand).  Have been meaning to figure out
from where I can steal power off the board.  When not using PoE
voltages, I can swipe an unregulated 12-15 volts and remain RS-232
legal.  (likely more with voltage loss on the long 1-wire phone line).

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