Re: I2C questions

From: Dave Boland (NODARNSPAMdboland9_at_stny.rr.com)
Date: 02/27/05 

Date: Sun, 27 Feb 2005 00:08:22 GMT

Ian (and all),

I was not very clear in my original append. I'm not
creating an I2C device. I want to understand it better,
particularly the preassigned addresses, and then use it with
existing devices to implement a design.

The processor has an I2C port on it which will be used for
two purposes. The first is to query EPROM's to get
information on the daughter cards attached. The second use
is normal I2C devices like DAC's, ADC's, Voltage to
Frequency, etc.

Going back to the first use, my concept was to have a block
of addresses reserved for the group of EPROM's used to hold
the daughter card information. This would be the first 4
bits of the I2C address. The rest of the address would be
coded as the card umber (1, 2, 3, etc). Doing this makes
the software easier to write because it always looks at a
maximum of 8 known addresses to see if there is a daughter
card and get information about it. Looks like this flash of
brilliance (meant kiddingly) won't happen.

Hope that helps and thanks to all of you that have responded.

Dave,

Ian Shef wrote:
> Neil Kurzman <nsk@mail.asb.com> wrote in news:421D6146.B2A14EDD@mail.asb.com:
>
>
>>
>>Dave Boland wrote:
>>
>>
>>>An I2C bus will likely be implemented on a design I'm
>>>working with. Went through the spec., FAQ, and some other
>>>documents and still have some questions. Hope some of you
>>>with hands-on experience can help answer them.
>>>
>
> <Discussion about I2C addresses snipped.>
>
>>On your design you can use any address for anything. If you want to
>>sell the chips as I2C. Then Phillips cares. Otherwise you are limited
>>to the address ranges the chips support. Phillips lists the general
>>groups. Your chips can do what you want. There is not a broadcast
>>address, so I assume your are doing your own thing.
>
>
> Actually, Philips seems to care regardless. They say:
> ===========================================================================I2
> C Patent Information
>
> The I2C bus is protected by patents held by Philips. Licensed IC
> manufacturers that sell devices incorporating the technology already have
> secured the rights to use these devices, relieving the burden from the
> purchaser.
>
> A license is required for implementing an I2C interface on a chip (IC, ASIC,
> FPGA, etc). It is Philips's position that all chips that can talk to the I2C
> bus must be licensed. It doesn’t matter how this interface is implemented.
> The licensed manufacturer may use its own know how, purchased IP cores, or
> whatever.
>
> This also applies to FPGAs. However, since the FPGAs are programmed by the
> user, the user is considered a company that builds an I2C-IC and would need
> to obtain the license from Philips.
>
> Apply for a license or text of the Philips I2C Standard License Agreement
>
> US and Canadian companies: contactMr.Piotrowski(pc.mb.svl@philips.com)
> All other companies: contact Mr.Hesselmann(ps.mb.svl@philips.com)
> ===========================================================================
> [from page 157 of
> http://www.standardproducts.philips.com/products/collateral/i2c/pdf/presentat
> ion-designcon.pdf ]
> [similar to page 50 of
> http://www.standardproducts.philips.com/support/appnotes/i2c/pdf/an10216.pdf
> ]
>
> In short, if you use commercial off the shelf I2C components, you are covered
> (and would then not be having these questions about addresses because the
> components would have Philips-assigned base addresses). If you are having
> questions about addresses, it is because you are designing your own parts
> (ASIC, CPLD, FPGA, etc.). Philips's position is that you need a license.
> Presumably, when you get a license you will get assigned addresses.
>
> I am not saying that I agree or disagree with this. I am not a lawyer and I
> am not expressing a legal opinion either. I just think that you should be
> aware of the Philips position on what you are doing.
>
> If you are building one of something for a prototype or a school project, I
> don't think that you need to worry about the "I2C police" hunting you down.
> If you are going to be building and selling these systems, you might want to
> check with your legal department before proceeding.
>
> Good Luck!
>
>

Relevant Pages

  • Re: I2C questions
    ... > On your design you can use any address for anything. ... > to the address ranges the chips support. ... Philips seems to care regardless. ... A license is required for implementing an I2C interface on a chip (IC, ASIC, ...
    (comp.arch.embedded)
  • Re: Summarizing the PWC driver questions/answers
    ... People are free to go use BSD if the GPL is ... > results from Philips, we might not be here arguing. ... > you don't like a partially binary driver, then I suggest you, too, ... choose the parts of the license you like or don't like. ...
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