[arm-allstar] Analog inputs on BBB

[Elliott L]

Hi Doug,

Thank you for your quick reply!

I am going to try what is suggested in that link -- it sounds exactly
right. I will try the reboot after I make another backup.

With regards to the input level, this particular circuit cannot create more
than about 0.770 volts, so I think there is a reasonable expectation of not
exceeding the headroom. But I'll pick up a zener if I see one.

The USB solution is probably better since it would work on any computer, in
particular a RPi, which will be an upgrade I make in the near future.

Thanks again for your continued support on Allstar,

--E

On Mon, Jan 2, 2017 at 7:42 PM, "Doug Crompton via arm-allstar" <
arm-allstar at hamvoip.org> wrote:

> Elliott,
>
>  First of you may already know this but let me warn you that the ADC pins
> are max 1.8 volts on the BBB. So you need to scale anything down and make
> sure it does not exceed that. A zener and series resistor would be a good
> idea for protection.
>
> The later kernels abandoned or changed the cape manager. I don't remember
> exactly at what point that happened but Dave would know. Here is a link to
> some info that might help. If you do need to upgrade and recompile you
> could experiment on an SD card copy of what you have so you can go back.
>
> https://gist.github.com/matthewmcneely/bf44655c74096ff96475
>
> As a side not the Arduino boards (nano) have ADC inputs and could be used
> to read analog voltages. This would be done via USB and would be
> independent of the processor board. This might be a better approach should
> the BBB method not work out. The BBB is becoming an unsupported board  and
> it is not clear how long there will be updates for it.
>
>
>
> *73 Doug*
>
> *WA3DSP*
>
> *http://www.crompton.com/hamradio <http://www.crompton.com/hamradio>*
>
> On Mon, Jan 2, 2017 at 8:31 PM, "Elliott L via arm-allstar" <
> arm-allstar at hamvoip.org> wrote:
>
> > Hi All,
> >
> > Does anyone know how to access the analog inputs on the beagle bone black
> > using the Ham VoIP release with kernel 3.16? I do not see any of the
> usual
> > entries in /sys for the analog pins. I do see something for the GPIO pins
> > in /sys/class/gpio/ which looks functional, but not analog.
> >
> > I have wired the first analog input pin of the BBB's header to the IF
> > amplifier in my GE MSTR Exec II receiver, and I am hoping to be able to
> > report signal levels over the air by reading out the voltage. I remember
> > some repeaters having this capability "back in the day" using expensive
> > computerized controllers. Should be a piece of cake with a real computer
> > available.
> >
> > I know these ADCs are pretty low quality but I think for low-precision DC
> > measurements they should be sufficient.
> >
> > Any help before I start upgrading packages and breaking stuff would be
> > greatly appreciated ;-) Once I get the script working I will share it
> here.
> >
> > Happy New Year all,
> >
> > --Elliott, W6EL
> > _______________________________________________
> >
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> >
> > Visit the BBB and RPi2/3 web page - http://hamvoip.org
> >
> >
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