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nebulight avatar image
nebulight asked

Digital Input for a tank monitor? dbus? Anyone working on it? I've got $100 to start a fund.

I have no programming experience and a novice when it comes to this sort of thing. I have setup a raspberry pi with a 7 inch touch screen. That is working with my multi (with MK3 adapter) so far (mppt and bmv soon with USB adapters). I have a camper van with three tanks:

30 gallon fresh water
10 gallon waste water
5 gallon diesel (with resistive tank sender)

I'd like to add external tank senders to each of the other tanks and get them to show up on the venus. The external tank senders are digital that send 0-5V. Another user has this https://www.ferriellosales.com/monitoring-systems.html but he made some complex board to take that signal and convert to a resistive value: https://github.com/aaronsb/Arduino/blob/master/tankmonitor/Readme.MD

That's pretty amazing but probably way WAY above what I would be able to cobble together. He mentions writing a dbus driver. Does that mean it would take a digital input signal and somehow get it to the tank info? I purchased this as it was suggested for my resistive tank sender:

https://www.abelectronics.co.uk/p/50/expander-pi

It also has digital inputs/outputs. Could those be used to to read the signal from the tank sender then get that into the venus OS and into a Tank value?

Not sure if this is allowed or not, but....

If so, and it's just a dbus driver that needs written, I'll chip in $100usd to start a pool for anyone willing to take on this project. Anyone else can feel free to chip in if they are interested?

Venus OSRaspberry Pitank monitor
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ben avatar image
ben answered ·

What senders are you actually using right now?

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nebulight avatar image nebulight commented ·

I currently do not have any sensors in the fresh or grey tanks. The diesel tank has a resistive 240-30ohm

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ben avatar image ben ♦ nebulight commented ·

In that case, you can get external senders that output resistive or N2K values, and that might let you avoid having to construct a custom driver.

It's also possible to write a driver, but then I think you'll also need an ADC for your RPi to be able to read the 0-5V. Not that that's a big deal, but it's a small, extra complication.

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nebulight avatar image nebulight ben ♦ commented ·

I already have an Expander Pi on order, and I've been hunting for external sensors that output resistive but I haven't found any resistive or nema. And if I did NEMA I'd have to get CAN working on the Pi. Do you know of any Resistive senders that can be mounted externally? and the 0-5v wouldn't that be the digital input? I thought the ADC was for the resistive side of things?

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ben avatar image ben ♦ nebulight commented ·

True, for N2K you'd need a CAN transceiver for your Pi.

Look at BEP TS1 for an external ultrasonic sender that will create a resistive output. It's known to work with CCGX/Venux GX.

0-5V is an analog range. You'll need an A/D converter to measure it.

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nebulight avatar image nebulight ben ♦ commented ·

I’m trying not to drill into the tank which is why I want external. Maybe for the grey tank, but not for the fresh water tank. Thanks for this info. Should be doable for the grey.

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