Kit required to connect microcontroller to Rasbperry Pi server


I’ve been using this device for a while:

One end monitors your grid power consumption via a sensor reading the LED on an electricity meter. The other end stores the data and makes it available via an LCD screen with buttons.

I plan to make a home brew version that reads the meter and transmits the data to a RaspberryPi. It’s a rural-fringe property so I’m looking at a distance of about 100m from the meter to the home.

Lora seems to be the way to go. I need a board that can sit in an electricity meter box where external temperatures might reach 45C (I’m in Perth). It just needs to monitor an LDR and count the pulses from the meter LED and send the data to my RaspberryPi. Low power consumption would be good so I don’t need to change the batteries too often.

What board would you recommend for the meter box, and what would I need at the RaspberryPi end?



Circuit Python support would be good, but I can do Arduino Processing.

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I’d look at the Pycom LoPy and use plain LoRa, not LoRaWAN (i.e. don’t use TTN). There’s an example Tutorial at:
Light Sensing
LoRa gateway
is how to make a direct link.

Just be aware that ACMA has some very clear rules on LoRa, so make sure you use 915Mhz and limit your traffic rate.


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That’s very helpful, thanks Dave.

OK, so say I put a Pycom LoPy at the meter box have a networked RaspberryPi at the house, what can I use to get the Pi to talk to the LoPy? Do I need another LoPy or is there another option? Say a hat, USB device, etc.

So - found this:

But perhaps it would be cheaper just to buy two Pycom LoPy boards and connect one to the pi via WiFi.

If you have LoRaWAN coverage, the LoPy inside the meter box could send data directly to the cloud (The Things Network, forwarded on to whatever end point you want), allowing it to be accessed by anything else connected to the internet (Node-RED, IFTTT, a Raspberry Pi on WiFi).

If it doesn’t have TTN LoRaWAN coverage, then direct LoRa could be used, with a LoPy either side. Though that does seem to be a clunky and expensive setup.

There are lots of ways to go about it, as always!

Thanks Graham, I’ll have a look at LoRaWAN vs. a point-to-point setup. All good hacking fun.

I had a look at the map here:

We’re a bit far out to connect, but no worries.

Say I had 2 devices:

The distance I need to cover is 90m. From the meter box itself to our home there will definitely be a tree or two in the way, and perhaps a slight hill obstruction. Ideally I’d be able to put one LoPy in the meter box itself with the LDR and the other inside the brick house. Is that likely to work? I see these aerials are also available:

Is it possible to run these up the pole above the meter box? Not sure how they’re connected, but perhaps a bit of coax?