Telemetry for external data

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Bill Arthur

Dec 3, 2020, 1:05:10 AM12/3/20
to Aprx software
I've figured a fairly simple way to send external telemetry via aprx.
I'm setting up a solar powered digipeater so voltage, current and wattage readings are important.
I found an awesome device at Adafruit, INA260 measures and passes the info via GPIO.

A small python script converts the data and formats a text file.
aprx grabs the .txt file and sends it as a beacon.

So if any of you rush off and order an INA260 let me know and I'll send my script and info.
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Alfredo Vania

Dec 15, 2020, 11:34:47 AM12/15/20
Hi Bill, I use Adafruit MCP3008 instead of INA260.

You can find attached a simple python script which acquires the following temperatures and attach them after my standard text beacon:
- cpu temp (from operative system)
- tx temp (MCP3008 reads an ntc on the tx heat dissipator)
- ambient temp (MCP3008 reads an ntc in the shack)

It's not necessary to create a txt file, because aprx can read the std output of the script using "beacon exec".
In aprx.cfg I added the following line:
"beacon exec /home/pi/Applications/aprx/ via WIDE2-1"
Obviously you have to change the path of your script.

I hope this helps,
Alfredo IZ7BOJ
See my aprx web dashboard here:

Il giorno gio 3 dic 2020 alle ore 22:43 Bill Arthur <> ha scritto:
Here's the python application. (.py changed to .txt)
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Alfredo Vania

Dec 15, 2020, 11:39:11 AM12/15/20
Sorry Bill,
It refers to mmdvm dashboard, but I integrated the telemetris in too.

Bill Arthur

Dec 15, 2020, 1:09:20 PM12/15/20
to Aprx software
Hello Alfredo,

Thanks for posting your experience. I had not considered using the exec beacon, but now you have me thinking.

I had considered an approach similar to your MCP3008, but my primary measurement concern was battery current.
Using a 75mv/A current shunt would work but it was messy and didn't have the accuracy I wanted. 
The INA260 was the easiest solution for me. However, if I need to add more inputs I'll consider the MCP3008.

At present my five telemetry channels (max for aprs) are battery current, battery voltage, power, cabinet temp and cabinet humidity.
I am going to swap cabinet temperature for solar radiation in the winter, perhaps switch back to temp in the summer months.
I have found the ideal size solar panel but have not yet found the ideal battery.  It would be impossible without the telemetry.

Again, thank you for sharing. Your ideas and experiences are quite useful.

Best Regards,

Alfredo Vania

Dec 15, 2020, 1:46:15 PM12/15/20
Hi Bill,
nice to hear that you're working on a solar powered digi. I'm going to build one too and it would be nice to exchange experiences, but it's better to write in private and don't spam the group.
Alfredo IZ7BOJ

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