[arm-allstar] Analog inputs on BBB

[Doug Crompton]

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
> _______________________________________________
>
> arm-allstar mailing list
> arm-allstar at hamvoip.org
> http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar
>
> Visit the BBB and RPi2/3 web page - http://hamvoip.org
>
>