What's wrong with 1-wire?

A Google Groups search for 1-wire in sci.engr.control returns only about 5
results. Why is it almost never talked about here? Is there something wrong
with using it as an industrial control system?
The Dallas/Maxim 1-Wire bus looks nice. The idea of needing only "one wire"
makes my cheap-gimmick-radar go off. It seems like there must be a trade off
for the convenience of needing only one wire. Also, it's not that much of a
convenience. If I have to run the 1-wire and ground, I can easily run a
couple more wires. If that were the only selling point, it wouldn't be that
much. More than that, Maxim's chips appear easy to use and the whole system
is flexible with generous limits on distance and number of devices, and data
rates up to 142kbps. There are all-in-one serial com interface chips, ADCs,
DACs, EEPROM, timer, serial number, battery monitor, different sensors and
GPIO chips. They are inexpensive compared to off the shelf products and
other fieldbuses, and a lot easier than using microcontrollers.
Reply to
Brook Stevens
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"1-wire" is a bit of hype. It should have been called "1-pair".
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Reply to
John Popelish
Something like 2-Wire then isn't it? Don't they all pretend that ground doesn't count? Of course the other reality of one-wire is the strong pull-up requirements for certain functions when parasitically powered, and the 12V needed for certain parts that use flash memory. I suspect that the 12V requirements don't exist for newer parts.
All in all though, I agree with the OP. I don't often see people recommend the 1-wire stuff even though they have some really nice parts. Talking to them is kinda odd, but I really don't see how the protocol could work any other way. Implementing a bus search in a micro using assembler *is* confusing. The algorithm seems much better suited for a recursive solution.
I wrote a search routine in assembler (with CRC checking compliments of Scott Datalo) for the PIC a few years ago. When I mentioned that I'd gotten it working to the piclist mailing list, I was inundated with email requests for a copy. It really surprised me. Given the way things are today, I probably shouldn't have *given* it away so freely.
Reply to
Anthony Fremont
You're looking in the wrong place. Try this instead: "1-wire" group:*embedded* returns 270 hits.
These are components, not systems unto themselves. There's a difference between building a control and using one, which is reflected in where the bus is discussed.
Reply to
Gene S. Berkowitz

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