Subject:
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Re: Brainstorms
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 13 Aug 2002 18:39:17 GMT
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Viewed:
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1118 times
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In lugnet.robotics, harbaum@tm.uka.de writes:
> Hi,
[snip hot pluggable]
> > ago and I don't remember all of the details. It took either a zero-length
> > read or a zero-length write followed by a check to see if the clock line
> It's way simpler: You just send the address and wait for the acknowledged via
> the data line. Then you just don't continue ... you don't even need read
> access to the clock line for this.
That is only a partial bus scan. It does not tell you what is at
each address.
A full bus scan allows people to plug arbitrary devices into the bus
and allows the bus master to to reliably figure out what has been
plugged in and where. Bus conflicts are either designed out or
detectable.
It is fairly easy to find out what addresses are occupied on an I2C
bus. Address conflicts may be detectable, but I sure do not know
how it is done. Figuring out whether the user plugged in a serial
EEPROM, an A/D, or another microcontroller is the far harder task
to solve. Again, I'm not saying it can't be solved, but until
someone really articulates how they plan on pulling it off, I will
remain skeptical of people who claim it is easy.
-Wayne
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Message has 2 Replies:
 | | Re: Brainstorms
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| (...) I have read this dicsussion, and have been most interested. From what I can understand (I have no current desire to read the I2C spec) the random ID number will identify that device on the bus once it is detected (or the permenant number, (...) (22 years ago, 13-Aug-02, to lugnet.robotics)
| | | Re: Brainstorms
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| (...) I thought Philips kept a master registry of all the hardwired I2C addresses allocated to each chip vendor? That should mean that just reading the hardwired address is enough to tell you what *kind* of device you've found. ---...--- Steve Baker (...) (22 years ago, 13-Aug-02, to lugnet.robotics)
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Message is in Reply To:
| | Re: Brainstorms
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| Hi, (...) Weird idea ... (...) It's way simpler: You just send the address and wait for the acknowledged via the data line. Then you just don't continue ... you don't even need read access to the clock line for this. IMHO something that can carry (...) (22 years ago, 13-Aug-02, to lugnet.robotics)
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