[arm-allstar] bbb controlling WX Receiver

[Mark Herson, N2MH]

Hello to the Group,

I am happy to announce that I have my first bbb up and running in
production controlling my NOAA WX receiver here in NNJ. What makes this
bbb a little interesting is that I'm using several gpio pins controlled by
shell command line statements in a script file called by Allstar to
control which WX frequency is heard.

There's a pretty good web page out there which describes how to use gpio
in this manner:

http://www.armhf.com/using-beaglebone-black-gpios/

Essentially, the whole thing works like this:

1. An initialization script is called by rc.local at boot time. This
script defines which pins will be used and sets them low.

2. Individual scripts for each frequency. Included in each script is a
sleep statment which then calls the Assterisk WX rcvr turn off code after
4 minutes.

3. An overall turnoff script that turns off the WX rcvr and unselects all
frequency control leads.

4. When a gpio pin is turned on, it puts out 3.3 volts which then is used
to turn on an NPN transistor which then grounds the appropriate frequency
selector lead coming from the WX rcvr. BTW, the WX rcvr is a 40 year old 2
freq Motrac VHF receiver that I had laying around. And, it still works!

If anyone is interested in listening to it, I'll be happy to send the
control codes.

73, Mark, N2MH