[arm-allstar] 4x4 Matrix Keypad Command Entry

Doug Crompton wa3dsp at gmail.com
Tue Sep 18 16:25:51 EDT 2018


 No, you are not off your rocker. In its simplest form this could work but
a script would need to be written that would scan rows or columns and
detect contact closure. A better approach would be a hardware decoder like
this -


Which would put out BCD that could be decoded with 3 or 4 bits of Pi GPIO.
I already wrote a BCD channel steering script and it could be easily

*73 Doug*


*http://www.crompton.com/hamradio <http://www.crompton.com/hamradio>*

On Tue, Sep 18, 2018 at 2:14 PM "Travis French via ARM-allstar" <
arm-allstar at hamvoip.org> wrote:

> Good Afternoon,
> I seem to recall at one point where someone referenced the concept of
> using a matrix keypad to enter commands into a node. This concept is
> something that I am interested in but I could not find the original email
> that spoke of it nor any how-to's that went into detail on this unless I
> missed it.
> I have a radio-less node on my desk and a RF mobile node in my truck that
> I was thinking this would be great for. Especially in the mobile. It may
> seem trivial to some but a dash mounted keypad would require only one hand
> to operate in lieu two for the mic DTMF entry let alone using a smart phone
> to dial in through IAXRPT. I have been a ham since 1999 and it still fells
> awkward to key DTMF commands into the mic while driving. Not to mention,
> this could also help with folks that are having DTMF decode issues with
> their radioless nodes. Just a thought. Maybe a win win.
> In my node enclosures, I have plenty of real estate to mount 4x4 matrix
> keypads. In fact, I have already ordered a couple to play with in the event
> that this is possible. I have done some research on how the Pi can
> interpret the key presses from a generic perspective. If I recall it
> correctly, someone here mentioned that a script could be set up to monitor
> for the * key as the start of the command string and the # for the execute.
> Of course with something like 3(node #) in the middle or a *76# to
> disconnect all.
> Am I off my rocker here?
> Is this possible? Has anyone else done this?
> If so, I would love to learn how to do it. I guess it is "how to get
> asterisk to respond to the interpreted key strokes" is where I get lost'
> Any help would be greatly appreciated.
> Travis E. French - K2PCB
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