ARMweb and ULN2803

[YahooArchive]

Greets,

I'm brand new to embedded systems development -- I've been programming
professionally for 20 years, everything from batches and scripts to device
drivers. I've used C/C++ and numerous incarnations of BASIC extensively,
hopefully some of that experience will overlap this venture.

I just ordered the ARMWeb Eval kit, I probably should've waited to see what's
included with it before posting here... but I want to get the jump on this
thing, and resolve what I perceive to be risk areas ASAP.

My first project is a well pump remote controller, using an IP network as
connective media (the ARMWeb's ethernet port will be connected to a long-range
802.11g radio.) Phase 1 is the pump side, phase 2 will be the tank side (which
I will simulate on a PC for testing phase 1.)

Needless to say, the pump side will need to operate a relay; from what I have
read, I should use a ULN2803 to facilitate this?

So the question is, are there any diagrams/docs/examples of exactly how to
wire-in that chip to ARMWeb built-in outputs, and connect it to a relay?

I was browsing the Jameco site, looking to order a few ULN2803's, and happened
across the VELLEMAN K2633 relay board
(http://www.jameco.com/Jameco/Products/ProdDS/239476.pdf) -- could this be
controlled directly by an ARMWeb? (It looks like the schematic for this hands
me a solution that does not involve a ULN2803?)

Suffice to say, any relevant examples would be greatly appreciated!


TIA,
Mark McGinty

[YahooArchive]

> Needless to say, the pump side will need to operate a relay; from what I have
read, I should use a ULN2803 to facilitate this?
>
> So the question is, are there any diagrams/docs/examples of exactly how to
wire-in that chip to ARMWeb built-in outputs, and connect it to a relay?

The ULN2803 is the easiest way to do it assuming the relay coil requires less
than 500mA to close.

Solder in the ULN2803, connect the common to the power supply of the relay, for
the path to dump the current when the relay opens.

As for software IO(31) = 1 will close that pin.

Details on the circuit (link in Support Page)

page 248 in
http://www.ckuehnel.ch/PDF/bs2pCommnFeat.pdf

There are also some other entrees in this Forum.

[YahooArchive]

Mark,

Please keep me posted on this project. I am working on a similar
project. Do you
have a web page for this??

Have you determined which radios you are going to use? I would
recommend the
Ubiquity Bullet2. Low power and well designed. What is 'long range"?
What power
requirements are you using?? Grid power or solar??

Are you going to monitor the pump schedule ( SNMP )?
> My first project is a well pump remote controller, using an IP network as
connective media (the ARMWeb's ethernet port will be connected to a long-range
802.11g radio.) Phase 1 is the pump side, phase 2 will be the tank side (which
I will simulate on a PC for testing phase 1.)
>
> Needless to say, the pump side will need to operate a relay; from what I have
read, I should use a ULN2803 to facilitate this?

Here is another group that may be better suited to answer this question:

hbrobotics digest subscribers hbrobotics@googlegroups.com>

It is a robotics group. They currently are having a discussion about
robot motor controls.

--
William Estrada
MrUmunhum@popdial.com

[YahooArchive]

Got it working, thanks! The thing that was unclear was that "U6" as drawn on
the board is essentially a socket for this IC! From there it was all downhill.
I wired-in a 12V relay I had laying around, its contacts are rated at 12A @ 120
VAC -- massive overkill for what I'm doing, but I want this to be
over-engineered.

Now on to the task of finding a suitable enclosure and external wiring... but I
don't want to stray too far OT here.


Thanks,
Mark