Actually I just did this - 1 wire bidirectional over a very erratic 
connection.  Look up "LIN" bus.  There are PICs that implement it, or at 
least some part of it, in hardware.  I used a LF1320 and a SN74LVC1G07 
(SOT23-5) on the PIC uart TX, with a 1K pullup on the wire, and my own 
real simple protocol.  Worked great.

J

PicDude wrote:

> On Monday 07 August 2006 17:52, James Newton, Host wrote:
> 
>>>I have determined at this point that I can reproduce
>>>equivalent functionalities of the DS2450, DS18B20, and others
>>>using a PIC.  It will take me some weekends of
>>>development/coding, but I feel it will be best in the long
>>>run and should eventually recover the costs.  I do like the
>>>1-wire concept, but now need to figure out if changing the
>>>specifics of the protocol and associated timing will still
>>>violate their IP.
>>>
>>>Cheers,
>>>-Neil.
>>
>>I understand that you may wish to do this as a "for profit" project, and
>>this assumes that it could actually be done, but if you were to "open
>>source" a design, there is effectively nothing that they can do to stop the
>>publication of a program for a PIC that duplicates the function of one of
>>their devices. They may be able to shut down one web site with that code
>>posted, but as soon as they do it, 50 others will copy the code and the
>>fact that they shut down the page will be posted on all the news channels
>>(e.g. digg, slashdot, etc...) and they will just be spreading the hate. Ask
>>scientology about that. Takedown orders have exactly the opposite effect.
>>
>>I've never received a take down letter yet... I'm sort of looking forward
>>to my first one. Bad attitude, I know.
> 
> 
> 
> This will be a commercial app for me, so I want to find out for sure if the 
> concept of 1-wire is copyrighted, or the protocol specifics.  I doubt the 
> concept can be copyrighted, especially since I won't need the parasite power.  
> What I really need is the ability to have multiple devices communicate 
> bidirectionally along 1single wire.
> 
> Marc, you are the expert at everything 1-wire -- know anything about this?
> 
> Cheers,
> -Neil.
> 
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