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Author Topic: IOT - Our bus on the internet  (Read 734 times)


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IOT - Our bus on the internet
« on: August 21, 2016, 11:01:58 AM »
Hope everyone is having a relaxing and productive summer. My nephew and I are working on a project during school break and are hoping someone can help us with some useful information before he has to head back to start junior high.

In the spirit of the Internet-Of-Things (IOT), our objective is to put the motorhome on the internet. So far, we can use our smartphones to view the house and chassis battery voltages, state of the solar panel, temperatures, LPG level and we can turn lights, AC, water, water heater, etc. On/Off.

The one that we need help with is sensing tank levels. The existing system uses five probes in each of the three tanks (Common, Sense, 1/4, 1/2, 3/4, Full). We want to sense the levels with a micro controller. With the existing system, pressing the Fresh button indicates on the LEDs that the tank is 3/4 full. Voltages relative to ground are as follows:

Common = 9.5V
Sense     = 5.8V
1/4         = 5.8V
1/2         = 5.5V
3/4         = 4.9V
Full         = 5.0V

If you can offer some input on the algorithm for distinguishing wet probes from dry with varying conductivity of the solution being tested, we would appreciate it.


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Re: IOT - Our bus on the internet
« Reply #1 on: August 21, 2016, 11:18:08 AM »
Don't waste your time. Those levels are never correct. The probes get toilet paper on them and stop being functional within the first year.
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  • Posts: 2
Re: IOT - Our bus on the internet
« Reply #2 on: August 21, 2016, 11:44:23 AM »
From what I have read online, that may be true of the two-wire resistor-ladder type of sensors. Our system has been working reliably for the three years we have owned and used it.

By the way, I believe you are supposed to wash out the toilet paper, not leave it in there. ;)