Serial comms on VCC line

[MegaADY]

You got the point ! That's why I thought it might not work ! Although, someone did it, I don't know exactly how... Forget the 3rd wire...I just can not use more than 2 wires

[Melanie]

No, it's irrelevant which end is supplying the power and which end is transmitting the data. Quickly, for example as I'm under pressure at the moment...

Slave is a 16F628 (building block of the modern world!). HPWM an output at say 40kHz... hardware cross-connect that back into one input of one of the on-board comparators. Take Hardware Serial out of USART or Software Serial out of any other pin. Hardware cross-connect that into your other Comparator Input. Take Hardware comparator output pin via Capacitor onto your Supply Line (yes, the supply will need a blocking choke). This will then transmit your modulated data signal back to the Master end. At the Master end, take via a Capaitor (PSU will need a blocking choke as well) into a demodulator (which if you chose the values correctly could be as simple as a Diode and a Capacitor), take it's output into USART or Software Serial pin. In it's raw basic form it's not exactly going to pass EMC specs but who cares anyway! It's not noise immune either, but repeat the data five times with a check-digit. Anyone with a problem with this concept, go read basic AM radio theory.

[sougata]

Hi there,

Can you please specify the following :

1. Does the slave consumes a fairly constant current ?

2. What is the baud rate required ?

3. Repetition rate of communication ?

4. Multi-Master / Multi slave needed ?

5. Exact scenario or implementation ?

6. Are you seriously involved or just a casual thread ?

Regards
Sougata

[Luciano]

Hi,

See these links.

DC-BUS transceivers

http://www.yamar.com/index.html
http://www.yamar.com/products.html


Reduced Cable Smart Motors Communicating Over the DC Power Bus-Line

http://darbelofflab.mit.edu/Progress...Report%208.pdf

Best regards,

Luciano

[NavMicroSystems]

Luciano,

thanks for the yamar links!

I have requested the full datasheets.
Samples will not be available befor end of Feb.

What I can tell so far is:
It is not going to be a cheap solution and will require some PCB space as there is quite some external components required.
(It's not the "single-chip" solution I was hoping it was)

So for MegaADY this is certainly some sort of overkill if he has to transfer just a "few" bytes at "low" speed over a "short" distance.

BTW.
How do you collect all those links?
Are you searching the web all day?
;-)

[Luciano]

Ralph,

My Internet digging machine has returned one more link.

SSC P485 PL Tranceiver IC

http://www.intellon.com
http://www.intellon.com/products/ssc/p485.php
http://www.intellon.com/pdfs/SSCP485...ical_Brief.pdf
http://www.intellon.com/pdfs/SSCP485_Ref_Design.pdf
http://www.intellon.com/products/ssc/P485.zip

My Internet digging machine:
http://www.kazimages.com/uploads/9370e41a0e.jpg

Best regards,

Luciano

[NavMicroSystems]

And I have digged out THAT one in addition.

[NavMicroSystems]

Ralph,

My Internet digging machine has returned one more link.

Luciano

and where did you find that image?

I know those machines, we have some of them in our neighbourhood, but they dig for coal, I'm not sure they can be configured to dig for information.

;-)