[TowerTalk] OR-2800PX Point and Shoot?

k2qmf at juno.com k2qmf at juno.com
Fri Mar 4 12:40:50 PST 2011

Hi Dan,

Very interesting input regarding the point and shoot issue...

It's a bit over my head but I will look into it.

Many Thanks and 73,
Ted  K2QMF

On Thu, 3 Mar 2011 09:44:40 -0500 Dan Zimmerman N3OX <n3ox at n3ox.net>
> I think your easiest bet is to use a computer and software like 
> DXLab.
> If you don't want a general-purpose computer in the mix, or if you 
> really,
> really want a knob, I'd look at talking to the RS-232 interface 
> with
> something like an Arduino (www.arduino.cc,
> http://www.sparkfun.com/products/9219) or other beginner 
> microcontroller
> board.  I like the Arduino because the language is simple, there is 
> a large
> community of total newbies using it,  and the board is all-in-one 
> and
> programmable over USB.  If the M2 control box is true RS-232 (with 
> plus and
> minus twelve volt logic levels) you probably need a MAX232 (
> http://www.sparkfun.com/products/316)  level converter chip between 
> the
> Arduino and the M2... but that's one chip and a few capacitors.
> I can't design the firmware for the thing, especially without 
> knowing the M2
> controller's language or having one to test on, but it might be as 
> simple as
> something like this:
> 1) in the firmware,  set up a serial connection and a digital input 
> for a
> button (analog input is set up automatically I think)
> 2) Read the position of a potentiometer (the "point" pot) on one of 
> the
> analog inputs using the function AnalogRead().  This gives a number 
> from 0
> to 1023 for a wiper voltage between 0 and the power supply of the 
> controller
> board.  Translate to a heading as desired (depends on the pot you're 
> using)
> 3)Read the digital input using DigitalRead().    if the button (the 
> "shoot"
> button) on the digital input is pressed, send the pot's heading to 
> the rotor
> using Serial.Print()  (this switch should be "debounced" by reading 
> it twice
> maybe 5-10 milliseconds apart and only considering it to be pressed 
> if both
> of those are the same)
> And that's pretty much it if the box accepts a heading in degrees as 
> a
> command.
>  You probably want a 360 degree pot, which might be a little hard to 
> find.
>  And if the rotor is capable of more-than-360 degree or continuous 
> rotation,
> you might need to be careful in how you send your commands.   That 
> is,
> unless the rotor controller itself decides which way to turn based 
> on the
> heading that comes in on the serial port.  If it does that, it 
> greatly
> simplifies things, and you just send a number over the serial port,
> probably.  If the homebrew controller has to be smart about 
> over-travel past
> 360 degrees, you'd need to add a lot of rules to the firmware to 
> tell the
> control box the right direction.
> You can probably do it for thirty bucks or so, plus the effort of 
> learning
> how to program the Arduino board... but like I said, there's a 
> large
> community of people who don't have any prior experience with
> microcontrollers doing things with the Arduino, because the people 
> who
> designed it were shooting for "as easy to use as possible."
> Here are some things I've built:
> http://n3ox.net/projects/stepperswitch/
> The first one accepts input from analog and digital pins and turns a 
> switch
> to switch bands on my big vertical.  The second one is an automated 
> band
> switch that sends and receives commands from Ham Radio Deluxe over a 
> serial connection and switches eight lines high and low.  Eventually 
> I'm
> going to fuse those two things together...
> 73
> Dan
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