I'll start this by saying I don't know what I'm doing. I aim to stay close to competent folks who help me. This journey kicked off when I was looking for a sensor to put on the Helium network for a project in local ephemeral wetlands called vernal pools.
I found the MakerFabs V3 option via @dirkbeer and ordered a few.
https://www.makerfabs.com/lora-soil-moisture-sensor-v3.html
The upside is they are cheap, available, and have a known working sketch on Arduino. All of those remain true. The downside is that they're kind of of a PITA to get to work when you're new to all this.
As an entry level geek, I got frustrated at the number of attempts it took to flash the device, which appears to be a combination of not using the MakerFabs suggested USB to serial/TTL converter and the Arduino sketch being right at the capacity limit of the device.
Now, I'm not a code guy. I looked around and found someone who is, asked him to look at and improve this, and this is what he came up with. Hopefully it's useful to more than just me.
Dirk's Guide: https://github.com/dirkbeer/Helium_MakerfabsSoilMoistureSensorV3
| Item | Link |
|---|---|
| Sensor | https://www.makerfabs.com/lora-soil-moisture-sensor-v3.html |
| 3.3V USB to TTL / Serial converter | https://www.makerfabs.com/cp2104-usb-to-serial-converter.html |