5V or 4.68V input isn't meaningful. The sensor has some input range and 4.68V most definitely falls into that. Could be a design choice that has no real implications.
On the other hand, if the device normally supplies 5V, just yours doesn't, then that's further evidence you have a faulty controller.
My money is on faulty controller at this point, but I think you'll need to find someone with electronics chops if you want to avoid just buying parts until it works again.
For what it's worth, I didn't mean take the sensor out of the wall, but just electrically unplug it from the controller to see what it does on its own when you turn on the water.
A frequency counter won't really help you here, I think. You already know to expect ~VCC/2 when water is running, and either VCC or 0V if it isn't. The speed of the square wave isn't very relevant.
Oh and be careful if you do end up trying it.
There's no safety risk in what I described, but reversing the power supply might very well fry the device.
With better tools, it would be easier to troubleshoot more precisely. An oscilloscope would help you understand what's going on, for example.
From what you describe, I'm actually starting to suspect the other end (the controller?) to be the problem.
One idea you could try before buying anything is to disconnect the sensor, supply it with 5V and ground (double check with data sheet!) and see what's happening on the output when there is flow. If you don't measure anything, as I would expect since the pin alternates between a floating state and ground, you then add a 10k or 50k ohms pullup resistor between 5v and output and measure again, and should get the levels you expected to see in the first place.
Don't know if you're comfortable doing this, but maybe you can find somebody to help you out?
Read your post again, and your readings are of course not in line with what I laid out. Are you measuring the sensor in-system?
If you are, the sensor might indeed be faulty. If you aren't, you probably need a pullup resistor on the output pin.
These flow sensors are usually hall effect sensors, with two or four magnets attached to a rotor with a little water wheel. When water flows, the magnets turn and create something like a PWM signal at the output (actually it's high level when magnet is there and low level when magnet is not there or vice versa). Measuring the pin with a slow multimeter, this would indeed give you approximately half the supply voltage when water is flowing, depending on a few other factors. So- readings sound sensible to me. To note that if the rotor stops with a magnet close to the hall effect sensor, you will read 5V (or VCC) at the output, but always VCC/2 when flowing.
Most of these sensors employ an open collector output stage, but that doesn't need to bother you with the readings you're getting, I think.
No harm in giving it a try, but I personally wouldn't bother with a selfhosted solution for it. Especially if you're not sure it will work out.
Well, paint me green and call me a pickle. More power to you if it works. 😊
Tangent, unsolicited:
Music lessons over video call, that has to be a real pain. I can't find it now, but there's an Adam Neely video where he talks about why online recording sessions can't work, as transmission latency works against the immediacy needed to play music together. He said it better than I can.
Except if your idea is to play in turns, but then capturing the thing you want to show... Can't you find another teacher closer to you?
Installing the Jellyfin add on into kodi takes a few minutes. Nothing much to consider, just try it and see if that changes anything.
I have a similar setup (rpi with OSMC, media hosted on file server) and prefer using Jellyfin as the source for all clients, as it keeps track of watched status across everything. It's not perfect, but better than without Jellyfin.
Anyone remember the Darknet Diaries episodes about a bunch of white hats from the Netherlands who managed to guess Trump's Twitter password twice? I think this was after he started campaigning for what would be his presidency, and then again a few years later.
Here's the first of the two episodes: Darknet Diaries: 87: Guild of the Grumpy Old Hackers mp3
Good job troubleshooting.