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Injecting UART into 3.3V DC and reading it back?

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Mangy_Dog

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Its been asked before but the truth is the threads were rather old and links a bit out dated.
I know the Yamar chips exist but theyre a bit expensive and im looking for a some what simple circuit design that I could maybe fit onto a small pcb roughly 10mm by 20mm...

has anyone got any ideas?
 

Strange I thought I had made a post about this already but I cant see it anywhere... So I guess I didnt hit send...

Anyway...
I need to find a simple circuit design for injecting UART into a 3.3v DC line to be received by a micro controller only a few inches away in another enclosure.
The receiving side only uses about 200mA maybe 300mA tops.

Im aware the Yamar chips are around but theyre too expensive and the data being sent back and forth isnt critical enough to warrant the extra cost. Also I have software level error corrections going on for the little hickups that might occur.

Does anyone have any simple circuit designs that might fit in a small pcb? roughly 10mm by 20 or 30mm?

Im assuming something like a few passives an inductor or two...

One issue im facing is running at 3.3V, it doesnt give a lot of head room (none at all really) I really would like to give a stable 3.3V at the vOut after the datas been demodulated...

Any ideas?
Thanks
 

Hi,

The second post gives at least a bit of technical informations.
Hopefully it´s not asking too much for a simple sketch with complete informations (drawing and text).

So it´s not very clear "what" and "why".

Correct me if I´m wrong. But you want a data communication via a 3.3V DC power line.
If so:
* Why no third/fourth wire for data?
* why not RF or optical (IR)?
* why UART? why not modem style ... or other solutions? (like DTMF...)

If you want to stick on a 2 wire solution: (3.3V power supply plus data)
* what about baud rate? continous, or data packets?
* what information do you send/receive?
* one way, or both directions?
* only one master/transmitter?
* only one slave/receiver?
* if one way: is the data direction the same as the power direction?
* small PCB: at Tx at Rx or both?

For sure any additional information about your application is helpful to find the best solution.
For example:
You will need different solutions depending on load (power). A power line data tarnsfer is more simple for
* an always ON incandescent light
* than a PWM´d DC motor
(from the view of noise, currents, voltage levels, margins...)

Klaus
 

Hi,

The second post gives at least a bit of technical informations.
Hopefully it´s not asking too much for a simple sketch with complete informations (drawing and text).

So it´s not very clear "what" and "why".

Correct me if I´m wrong. But you want a data communication via a 3.3V DC power line.
If so:
* Why no third/fourth wire for data?
* why not RF or optical (IR)?
* why UART? why not modem style ... or other solutions? (like DTMF...)

If you want to stick on a 2 wire solution: (3.3V power supply plus data)
* what about baud rate? continous, or data packets?
* what information do you send/receive?
* one way, or both directions?
* only one master/transmitter?
* only one slave/receiver?
* if one way: is the data direction the same as the power direction?
* small PCB: at Tx at Rx or both?

For sure any additional information about your application is helpful to find the best solution.
For example:
You will need different solutions depending on load (power). A power line data tarnsfer is more simple for
* an always ON incandescent light
* than a PWM´d DC motor
(from the view of noise, currents, voltage levels, margins...)

Klaus
I'll try and answer as best as I can...
Uart because thats what I have available. The master micro has this spare. But also the current design and program uses it. Changing to another data system would be an extra pain to deal with.

no extra wires because currently its all going through a custom hinge assembly. Which is proving to be a nightmare to make. While doable a huge amount of work is going into it and its becoming a problem.

So going through a solid hinge for power and data would be better in this project.

RF might be ok if its simple and low powered enough. But im not an RF engineer.
No IR, while doable as the two chassis do meet. It would break the aesthetic design.
Not heard of DTMF tbh.

I can only use two wires... Power and GND. Hence going through two hinges.

Baud rate, as high as reasonably possible tbh. 112k would be fine. 1M would be nicer...
Data is sent in burst packets roughly every 5ms. Mostly just relaying between two micros a main one and secondary one. Main one sends out mostly LED data to the secondary. And the secondary sends button state data back. Give or take some error correcting resends.
Id like this to be two way data.
And yes a small PCB. I'm happy working with 0603s or 0402s and extremely dense pcb designs.
Currently the foot print for the PCB could fit about 10mm by (at a max) 30mm.
 

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