[arm-allstar] Why Arduino?

[Doug Crompton]

The choice of I/O is really a moot point. It really does not matter. In the
end the amount of hardware and DIY experience needed is basically the same.
All this adds is a $3 (or less) nano. It also makes a much cleaner
installation. Would you rather have 6,8,10 or more wires running off the pi
or have a separate container with one or two USB cables going to it where
all the interface was made. Using the Pi you would have to build the Pi
into a case where LED's, radio interface electronics and radio connectors
were mounted. The bottom line is just because it is there does not make it
practical to use.

I have stated here several times the reason we did not go Pi I/O route.
Besides the amount of I/O needed and the cleaner installation the
possibility of EMI both in and out could be an issue. Yes you could use a
serial format like SPI or I2c from the Pi but there again you would need
hardware (a Nano?) to interface to external I/O. This method is also
hardware independent. Maybe we won't always be using a Pi.

In either case on or off the Pi a board would need to be designed for the
many who cannot build anything. That appears to be a large group today in
the ham world.

I would argue that the easiest way to do this is to modify a FOB but there
are many reasons why this is no longer working. The primary one being that
it is getting difficult to find a FOB that is not potted. Another is the
reluctance or inability of users to solder two wires on the pins of a
surface mount chip on a throw-away $3 FOB.

Also keep in mind that this project is basically DIY. Even the pre made
board when available will need to be wired up externally. Those who can't
build will buy one of the complete USB FOBS out there like the DMK-URI or
RIM.  There is no mandatory reason to use a Nano.

The software behind this is modular in that it will drive virtually any I/O
device. In the future other GPIO devices will be supported like FTDI or
even Pi GPIO if you want to go that way. Capable users can add their own
device and write there own SW if they desire. The Nano approach adds much
additional I/O to control fans etc. at a place where it becomes more
practical. Run one USB cable to the radio or repeater where all analog and
control I/O takes place. There are 14+ I/O lines plus the possibility of
two ADC lines that can be used on the Nano.

In the end hams are cheap and this offers a way to interface a radio to
Allstar at a very attractive price. The downside is that any method of I/O
that is not plug and play like the DMK-URI, etc. will require some DIY.

Assuming one were using the DMK-URI it would cost $150 for two nodes just
for the FOB. Using a nano you could do the same for under $20.



*73 Doug*

*WA3DSP*

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

On Tue, Dec 6, 2016 at 10:17 AM, "Thor Wiegman via arm-allstar" <
arm-allstar at hamvoip.org> wrote:

> The Arduino thing sounds cool but it leaves me with a question:  Why use
> an external microcontroller for this instead of the Raspberry Pi's GPIO?
>
> I've been hacking and slashing on the simpleusb channel driver (I'm not a
> programmer, what I'm doing is ugly) and had planned just to use the GPIO
> pins for COR and PTT.  But the Arduino project makes me wonder if I'm
> missing something.  If its not possible, or not advisable, to use GPIO for
> this then I'm going to waste a lot of time and feel really stupid.  Again,
> I'm not a programmer so I'm sure there's something I'm not understanding.
>
> Thanks
> Thor
>
>
>
>
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