Can we send Power and Data over 2 wires only?

I have a pool where I need to install sensors to measure it's water level. The problem is that I can't add wires to the pool because it would involve breaking up all tiles in order to get extra wires inside the pool. That's not an option.

Luckily the pool cover motor has 1 unused wire that I can use. The cover motor works with 2 wires for power (power is reversed for open/close movements. It's working on 12V DC). It also has 3 wires that go to a hall effect sensor (to get pulses from the cover used to keep track of it's position).

So I can use the GND wire of the hall effect sensor and the unused wire for attaching my sensors.

Now the question is: can I somehow provide power over 2 wires and send data over the same wires?

If yes, are there example circuits for this?

Hi @
Yes. this technology sends power and data over just 2 wires.
(despite having the name 1 wire).
https://www.maximintegrated.com/en/design/technical-documents/tutorials/1/1796.html

RV mineirin

I read about 1-wire before but looking at a 1-wire temperature sensor, for example, it has 3 pins. So it needs power + 1 wire for data?

You could also look here for a 2 wire power/data solution: Digital Command Control - Wikipedia

If works by swapping the 2 power rails in such a way as to deliver a signal through the timing of those swaps. The devices using the power (say model trains) have to use a bridge rectifier (or similar) to provide stable DC.

Hi @
Read the part that talks about "parasite mode" .

This mode only uses 2 wires.

RV mineirin

@ruilviana thanks but it's still unclear to me how you would see this as a solution to my problem?

Are there 1-wire devices that allow reading the status of a reed-switch (inside a floater in the pool?) or is there a way to use an arduino as a 1-wire device just needing 2 wires for power and data? I'm not sure how you see this working?

@6v6gt I'll read into this. I never heard of it before :wink:

I just found the DS2413 which is a i/o chip.

If I'm understanding this correctly I can connect a reed switch (that will trigger depending on the water level) to this DS2413 and read the status of the reed switch using 2 wires (1-wire parasitic mode). And I can add multiple DS2413 in parallel?

So I don't even need an arduino inside the pool. Just one arduino on the other end of the cable that communicates with the DS2413 chips

Right

1 Like

Of course. Always consult the device data sheet.

But not enough power to power a motor or too much voltage to make the protocol work.

I think the OP was a bit hasty in pressing the solution button.

To do what you want you have to modulate the data at a high audio frequency on the power lines using FSK ( frequency shift keying ) and then demodulated it at the other end using AC coupling to remove the high voltage of the motor current.

LIN bus.