Subject:
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1Wire vs I2C
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 26 Oct 2004 18:19:36 GMT
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Original-From:
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Bruce Boyes <bboyes@systronix/AntiSpam/.com>
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Viewed:
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855 times
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At 02:13 PM 10/26/2004 +0000, you wrote:
> > would comfortably fit into a 2x4 brick) - but instead provide a
> > simple bus interface (something like I2C) with small, simple
> > computers in every motor and sensor that would communicate with
> > the main computer to do their work.
>
> Any idea on how I2C compares to 1-wire?
I2C is much faster (100 Kbit I2C is the slowest, vs 14 Kbit 1Wire), more
reliable, but much shorter distance. Newer I2C can be 1 Mbit or more.
> I know that there 1-wire is being considered for some open-source home
> automation schemes because of the extremely low cost of interfacing,
> and the data rates seem comparable 115k for 1-wire vs. 100k for I2C
> but I am an expert with neither...
1Wire will never do 115 kbits reliably. The 1Wire overdrive option is not
reliable and few devices support it anyway. No one in industry uses
overdrive on 1Wire.
The serial adapters for 1Wire can talk RS232 at 115 kbits but that has no
relationship to the 1Wire side of the adapter.
I2C is inherently more robust due to separate data and clock lines. And
there are I2C buffers too to make it drive even more capacitance. We use
them on our TILT400 socket board.
1Wire uses self-clocking data which is inherently less reliable since noise
on the data/clock line can cause false clock transitions.
The common serial adapter DS2480B has some well known flaws. This is why
technology such as the iButton link (see ibuttonlink.com, available now)
and our future Industrial 1-Wire Interface are being developed.
1Wire is good for longer cable runs in non-noisy environments. It can be
good for secure building access and asset tracking (I2C has nothing to
offer in those areas).
Regards
Bruce
> -Rob A.
------- WWW.SYSTRONIX.COM ----------
Real embedded Java and much more
www.jrealtime.com and www.tstik.com
+1-801-534-1017 Salt Lake City, USA
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Message has 1 Reply:
 | | Re: 1Wire vs I2C
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| On Tue, 26 Oct 2004 18:19:36 GMT, Bruce Boyes <lego-robotics@crynwr.com> wrote: Big Snip! (...) Whew! Thanks for the insight! How does the component/driver cost compare? -Rob. (20 years ago, 26-Oct-04, to lugnet.robotics)
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Message is in Reply To:
| | Re: Mini-RCX
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| (...) I don't see a problem with the computer side of things - what concerns me is battery storage and power management. You can get *tiny* computers that would easily fit in this kind of tiny space - but the RCX motors need 9 volts - you would need (...) (20 years ago, 25-Oct-04, to lugnet.robotics)
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