Sharing power AND data over induction charger.

[Jonathan David Bond]

Is it possible to send a data signal through the same coils that provide inductive power.

I'm looking at a 5v-5v system and don't need more than 200-250mA (Max) output, probably half that really.

Failing that, is it possible to have a uni-directional data steam over NFC or some other close proximity wireless connection?

 

[Warpspeed]

I suppose you could modulate the frequency of the power being transmitted, that should not present much of a problem.
But sending data back the other way would be much more difficult.

 

[FlapJack]

https://www.radio-electronics.com/i...ry-charging/qi-wireless-charging-standard.php

This has some info on the data transmission protocol.

 

[Jonathan David Bond]

Thanks.

It would only be a one way transfer, but the data needs to change so just an NFC or RFID tag wouldn't be sufficient.

 

[FvM]

It would only be a one way transfer, but the data needs to change so just an NFC or RFID tag wouldn't be sufficient.

What do you mean? Any of these protocol standards can be used to transmit arbitrary data (even bidirectional, but you might use it in an unidirectional way).

 

[Warpspeed]

Thanks.

It would only be a one way transfer,

Which way ?
Same direction as power transfer, or back the other way ?

 

[Jonathan David Bond]

RFID/NFC "tags" can only be read/written to by an enabled device.

They don't act as a receiver/decoder to connect peripherals.

(Well, that's how I understand it anyway).

However, if it is possible to use 2 NFC transceivers to transmit data, I would be very interested (provided an induction charging loop wouldn't interfere with the data).

I only "need" to send the data in one direction, but that data has to be usable by the receiver, not just stored for later retrieval by something else.

However, 2 way data would be better, it's just not needed.

 

[FvM]

O.K., tags have no external interface connection, but the standard isn't restricted to tags. Your smartphone is e.g. using NFC for bidirectional communication. But in the present case you are relying on passive NFC mode respectively ISO14443A etc. card mode. Chips like NXP PN531 are supporting it.

 

[Jonathan David Bond]

Which way ?
Same direction as power transfer, or back the other way ?

Must have cross posted - sorry.

Same direction as power transfer.

- - - Updated - - -

O.K., tags have no external interface connection, but the standard isn't restricted to tags. Your smartphone is e.g. using NFC for bidirectional communication. But in the present case you are relying on passive NFC mode respectively ISO14443A etc. card mode. Chips like NXP PN531 are supporting it.

Thanks. I'll look into those.

My issue is size though. I need to try and keep the induction loop, and the NFC transceiver (if I use separate NFC) in a 4cm or less area.

I'm worried that if I use both, due to the close proximity, that the power would interfere with the data hence trying to save space and sending the data over the power instead.

 

[FvM]

Same direction as power transfer.

Technically the simpler part because it doesn't suffer from signal-to-noise limitations.

sending the data over the power instead

That's what I presumed with passive NFC/card mode. I assume Qi signaling does something similar. You should read a bit about these standards.

 

[Warpspeed]

Same direction as power transfer is easy.

Just shift the frequency up and down (frequency shift keying).
That will have no effect on power transfer, and its simple and easy to do at both ends.