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Old 01-17-2024, 04:18 PM   #1
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Default Integrating Garnet SeeLevel sensors into DIY van monitoring

My Coachmen Crossfit came with unreliable tank sensors. Garnet SeeLevel tank sensors integrated into my DIY camper monitoring system would be a big improvement.

My current monitoring system is centered around MQTT and Node-Red running on a Victron Cerbo GX and a Nextion touch screen, with ESP32's where needed for reading sensors and communicating between devices.

Options for integration include buying a SeeLevel control panel with any of Bluetooth, RV-C, or NMEA2000 interfaces, the latter two of which directly interface with Victron's Cerbo units and/or Raspberry Pi running Victron's OS.

Reading the sensors/sending units directly, without the Garnet control panel also seems to be possible - based on this post in a Raspberry Pi forum, where one of the participants (Jim G) figured out how to trigger and read the tank sensors/sending units directly.

I bought a couple of SeeLevel sending units and successfully dummied up a test using an ESP32 to trigger and read the sending units and a circuit similar to the one designed by Jim G. in the Raspberry Pi forum. It's working on the bench with two SeeLevel sensors attached to a water jug.



It's too cold to work out in the camper, so I'll not know if it's reliable in the real world until it gets quite a bit warmer. In the meantime, I've rearranged my display to accommodate tank gauges (lower left corner):



I figured I could either use (boring) green bars to show tank levels, or an appropriate set of emojis.

My code and a description of the circuit are uploaded to Github. To fully integrate the sensors, I'll need to modify my code to encapsulate the data into JSON formatted ESP-NOW packets, and come up with an algorithm to properly interpret the data (likely in Node-Red).

I'd also like to put a bit of protection on the 12v circuit feeding the sensors. I'm not sure how tolerant they are of voltage spikes and anomalies. I've no idea how to do that though.
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Old 01-17-2024, 06:59 PM   #2
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I have no idea what I just read, but your display looks really cool.

I have some old, but functional tablets that would be just great for such a setup (like a Galaxy Tab S2). Maybe a project for another year...

Not to derail your thread, but... Do you have any experience with/opinion of the Mopeka "Pro Check Universal Sensor" for such a purpose?
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Old 01-18-2024, 07:51 PM   #3
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Quote:
Originally Posted by Urlauber View Post
Do you have any experience with/opinion of the Mopeka "Pro Check Universal Sensor" for such a purpose?
No experience, but that Victron supports them with their Cerbo product line suggests to me that they're OK.
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Old 02-05-2024, 02:21 PM   #4
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Updates on this project:

I'm now using a circuit based on the one in the original post in the Raspberry Pi forum. It's reliable with three sensors in parallel at the far end of 20ft. of 20ga, wire, so it should work OK in the camper.

Quote:
Originally Posted by @Michael View Post
I'd also like to put a bit of protection on the 12v circuit feeding the sensors. I'm not sure how tolerant they are of voltage spikes and anomalies. I've no idea how to do that though.
I decided to inline a 12V-12V buck-boost converter to help ensure that the sending units see a clean, stable voltage source.

Quote:
Originally Posted by @Michael View Post
My code and a description of the circuit are uploaded to GitHub. To fully integrate the sensors, I'll need to modify my code to encapsulate the data into JSON formatted ESP-NOW packets, and come up with an algorithm to properly interpret the data (likely in Node-Red).
The data returned by the SeeLevel sending units is a series of bytes:

Code:
Byte 1: Unknown, perhaps a sensor ID
Byte 2: Checksum
Byte 3 - 11: Number from 0 -> 254 
                   indicating the 'fullness' of each segment of the sensor
                   starting from the topmost segment
Byte 12: Always '255'
Turning that series of bytes into a somewhat accurate percent-full number in NodeRed is still TBD.
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Old 02-05-2024, 08:58 PM   #5
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I use the Mark 1 Eyeball Tank Measurement System (METMS 1.0). 100% accurate and works perfectly every time.
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Old 02-06-2024, 06:51 PM   #6
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I use the Mark 1 Eyeball Tank Measurement System (METMS 1.0). 100% accurate and works perfectly every time.
Unfortunately 2 of 3 thanks are not translucent, and the one that is, is not readily accessible.
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Old 02-06-2024, 11:34 PM   #7
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Quote:
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Unfortunately 2 of 3 thanks are not translucent, and the one that is, is not readily accessible.
Right - that makes sense. Your system looks very nice. I'm still using an old JRV "dummy light" system, but I don't like to rely on it alone.
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Old 02-07-2024, 06:40 AM   #8
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I turn the water off, push down the pedal shine a flashlight in the hole and See Level. 100% accurate. Does not work with fresh or grey tank. I put a See Level system in a bus conversion 20 years ago, the external sensors do work well.
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