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Eric M. avatar image
Eric M. asked

RPi Tank Pressure Sensor

I have an RPi 4 running VenusOS and a 20gal water tank. Fairly new to RPi/GPIO etc., but I'm looking for the simplest plug n' play way to measure water level.

It seems the easiest and most reliable measure is a water pressure sensor. Has anyone found a USB version of this that just... works? All I'm seeing take 5v and output 0-5v, which I understand won't work with the 3.3v pins. Is there an accepted way to convert these for VenusOS sensor use, or calibrate for the voltage difference?

Am I missing a more convenient sensor options? I'd prefer to avoid shelling for the GX Tank 140 for one tank...

Raspberry Pitank monitor
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gone-sailing avatar image
gone-sailing answered ·

I personally don’t think water pressure is a good indicator of water level. I am planning to get one of these DF Robot tank level sensors to use with an Arduino. I don’t see why the same sensor couldn’t be used with Rasperry Pi GPIO. I will send the data from my sensor device over MQTT to the GX device (using the dbus-mqtt-devices driver I published recently).

Sensor : https://thepihut.com/products/gravity-non-contact-digital-water-liquid-level-sensor-for-arduino?variant=27741024721&currency=GBP&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&gclid=EAIaIQobChMIzabd-8Kp9gIVSu7tCh36qwYZEAUYASABEgLvrvD_BwE

DF Robot have a range of liquid sensors, details are linked off that page above.

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Eric M. avatar image Eric M. commented ·
Interesting, I'm curious why you don't think it's a good measure. I assumed with calibration in Venus it would work well.

The tank is pretty long and slim, in a van I drive daily and park on inclines, so I'm thinking the other measures wouldn't be super accurate for my use case, a lot of fluctuation...


Given your experience with the Arduino sensors, do you think theres a way to get the 5v nominal sender to work with the 3.3v GPIO's?

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Rene Mullie answered ·

You might get a sensor working on your RPi, but then it wont show up in VenusOS/VRM....

It has to be compatible with VenusOS, only way on Rpi is in conjunction with GXtank (Cerbo has built in ADC: any sensor can be hooked up)

Chrck this thread; my recommendation at the end!

https://community.victronenergy.com/questions/74302/cerbo-gx-water-tank-level-sensor-recommendations-n.html

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Eric M. avatar image Eric M. commented ·

Thanks for the helpful input! Was hoping to avoid the GX Tank which pushes my overpriced RPi past the cost of a Cerbo. Still learning about the ADC side of things... Seems like some constant returned percentage of supplied 3.3v should afford conversion into "percent of tank full," with a driver of some sort. I'm sure I'm missing some big understandings.


Also curious if there's not a simple USB chip that could do the conversion if Venus requires digital... something like this?

https://www.amazon.com/Hilitand-Interface-Sampling-Acquisition-Communication/dp/B086VN85NX/ref=sr_1_45

From my reading, RS485 just means ADC in a way, would the aforementioned 5v sensor hooked up to this, be accepted by VenusOS?

https://www.amazon.com/Feanteek-Industrial-FT232RL-Communication-Converter/dp/B08PL23NW8/ref=sr_1_6

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