Atduino to Arduino single wire communication

Projects Networking, Protocols, and Devices
1

Hi,
although I believe the answer will be: "you need at least two, the second one is for ground", I will ask anyway.

Is there a way to get two Arduinos to communicate having just a single wire between them?

I am trying to get two Arduinos to communicate to each other when two Arduino powered devices "touch" each other. The idea would be that, when the two devices are in contact through some conductive surface, they start to "talk" to each other. I am trying to have a single surface, but to my (little) knowledge looks like this simply cannot be done.

I guess at the lowest possible level, the question is: can a pin sense a change of level on a pin on another board by using a single wire between the two?

I understand the using opto-isolators would release the requirement for common ground, but that does not mean that only one wire can be used. Can anybody confirm this?

Are there alternatives to get two Arduinos communicate ONLY when they are in close proximity? This requirement will probably rule out any kind of wireless communication, correct?

Sorry for this long post, but being a beginner I wanted to show that before asking I tried to do my homework.

Thanks in advance for any kind reply,
Luca

2

lunobili:
the question is: can a pin sense a change of level on a pin on another board

yes i think it is possible using RX and TX, please watch this video "http://www.youtube.com/watch?v=xt6_GWLTxN4&feature=related" it might help you. Don't listen to other terminology in this video but just dig out your needed information from it.

3

Is there a way to get two Arduinos to communicate having just a single wire between them?

There are even ways without wires at all.

If you want to transmit the information electically you need two wires, one for the signal and one for the reference.

So in essence if you want to transmit trough one wire the reference must be in the wire at the same time.

Things that come in mind are doing it optically (light) or mechanically (vibration) ...

just some thoughts,
Rob

4

If you went optically (IR perhaps) with the emitters point down somewhat,that would keep the receiver from picking it up until closer in proximity. No wires needed that way.

5

This could turn into quite a fun project!

I have visions of maybe ten little robots meandering about an area, at random, but sometimes "bumping into" a fellow robot, "talking", changing behavior based on the "conversation".

Perhaps best developed with virtual robots in a software simulation? But what fun when working!

A Big Question to be decided early on: Do the conversations always have to be two way?

Back to the original question: "Connecting" the robots: My vote: send the messages on a light beam. CrossRoads has solved the "When are we close enough?" problem.

6

Hi guys, thank you very much for all your answers. I guess there are two main points I can take away from them:

  1. Indeed there is no way to use only one wire.
  2. IR communication seems to be a viable option that I really should explore further. Thanks!

Thanks again,
Luca