Using mmWave "RADAR" for tank level sensors?

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I’ve been working on a project that would monitor the levels in the waste tanks in our RV, and them automatically dump them when full. I started out planning on using some capacitive sensors, then went ultrasonic, but back to capacitive. Now I’m finding out that the capacitive sensors won’t work on all the tanks (not sure why). So it’s back to ultrasonic. But that would require drilling two holes in the top of the tanks. Not good.

But now I’m seeing these mmWave “RADAR” sensors from Seeed. It sounds like they may work. I’m hoping I can just place it on top of the tank, and sense the levels though the top of the plastic tank.

First of all, any comments on if this would even work? I don’t know much about the tanks, expect they are heavy plastic, not “milk jug” thin. They seem to have welds on them in places, so the plastic is meltable. The density seems to vary, I think that’s why the capacitive sensors don’t always work.

It looks like the mmWave boards use a companion ESSP32 (XAIO32) board, but I didn’t see any specifics on exactly which board works. Looking at the photo’s, the D0,-D8 pins don’t match the boards I have (ESP32-C3).

I’m guessing the boards act strictly as a I/O device, and the programming is done on the companion board? Using?? Arduino/C++?

I saw they have a Bluetooth chip, for??

There are two 24Ghz “devices” that sell for about $25, and a smaller one that sells for about $5. Not real sure what the differences are. But the programming information on the $25, seems to be “ESPHome” based?? (YAML as opposed to Arduino/C++?)

Any comments, information would certainly be welcome.

EDIT->

Ok, I found a little be more on what I was looking for, like which ESSP32 interfaces, etc… I didn’t see the next page link on the device page. I did see libraries for the device, but they are not on the Platformio platform yet, and some others are, so plenty of smooping to do there.

So any comments on viability for tank level sensing would be appreciated.

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That is odd :thinking: I use “capacitive sensing” with an ESP32-S3 on my water tanks (polyethylene ~5mm). No holes, quite accurate, long lasting.

I did try the “mmWave Radar” but it was triggered by any movement, in my case trees and animals.

I just use Home Assistant and ESPHome for the data. IF I had an RV, I’d definitely put in a Home Assistant based system :slight_smile: