I2C port IO chips

I looked around the web and could not find any sources of I2C port IO
chips other than Philips.  Seems to get most of their I2C parts, you
have to buy a couple thousand minimum.  I am looking for a way to add 8
or 16 IOs.  Some chips are port expanders, some are LED drivers; either
will work if they come in small packages.  

So who else makes I2C chips?  A google search turned up lots of stuff,
but no I2C makers.

"Ralph Malph" <noone@yahoo.com> wrote in message
news:400EB0D4.1CC8AD55@yahoo.com...
> I looked around the web and could not find any sources of I2C port IO
> chips other than Philips.  Seems to get most of their I2C parts, you
> have to buy a couple thousand minimum.  I am looking for a way to add 8
> or 16 IOs.  Some chips are port expanders, some are LED drivers; either
> will work if they come in small packages.
>
> So who else makes I2C chips?  A google search turned up lots of stuff,
> but no I2C makers.

You could roll your own out of an AVR or PIC. Plenty of I2C examples out
there.

Peter



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Ralph Malph wrote:
>I looked around the web and could not find any sources of I2C port IO
>chips other than Philips.  Seems to get most of their I2C parts, you
>have to buy a couple thousand minimum.

Have you checked usual distributors?
I don't know where you are but places like Farnell sell them.

Andy

Ralph Malph wrote:
> I looked around the web and could not find any sources of I2C port IO
> chips other than Philips.  Seems to get most of their I2C parts, you
> have to buy a couple thousand minimum.  I am looking for a way to add 8
> or 16 IOs.  Some chips are port expanders, some are LED drivers; either
> will work if they come in small packages.  
> 
> So who else makes I2C chips?  A google search turned up lots of stuff,
> but no I2C makers.

Beside that it can be done with IO ports in PICs and AVRs,
it could also be done with a small CPLD.

Rene
-- 
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net

> have to buy a couple thousand minimum.  I am looking for a way to add 8
> or 16 IOs.  Some chips are port expanders, some are LED drivers; either
> will work if they come in small packages.  

I2C is patented/copyrighted/trademarked. Look for '2-wire interface' parts, maybe.

Ralph Malph wrote:
> I looked around the web and could not find any sources of I2C port IO
> chips other than Philips.  Seems to get most of their I2C parts, you
> have to buy a couple thousand minimum.  I am looking for a way to add 8
> or 16 IOs.  Some chips are port expanders, some are LED drivers; either
> will work if they come in small packages.  
> 
> So who else makes I2C chips?  A google search turned up lots of stuff,
> but no I2C makers.

TI second source the PCF8574.
http://focus.ti.com/docs/prod/folders/print/pcf8574.html

They also seem to have dropped their prices....

Maxim have a range of IO exanders, with SPI and i2c versions.
There are also SMbus devices, and SMbus is a PC variant of i2c.
Unlike i2c masters, Slave i2c devices generally need some HW support - 
take a look at the Cygnal uC & Philips LPC9xx families, as most of these 
have i2c HW support, and many of the smaller uC these days price compare 
reasonably with the dedicated i2c IO options.
-jg

Andy Sinclair wrote:
> 
> Ralph Malph wrote:
> >I looked around the web and could not find any sources of I2C port IO
> >chips other than Philips.  Seems to get most of their I2C parts, you
> >have to buy a couple thousand minimum.
> 
> Have you checked usual distributors?
> I don't know where you are but places like Farnell sell them.
> 
> Andy

Sell what, Philips chips?  I am in the US.  I believe Farnell is
Australia, right?  

I could go to a lot of different distributors, but other than Philips, I
don't know of any parts.  All the distis I have checked only sell
Philips parts in large quantities.  I guess I could ask for a few dozen
samples.  So far Arrow is being very obliging.  They sent me a couple
hundred $.25 capacitors.

"Ralph Malph" <noone@yahoo.com> wrote in message
news:400F772C.BDC0B1A8@yahoo.com...
>
> Sell what, Philips chips?  I am in the US.  I believe Farnell is
> Australia, right?

No, Europe.

> I could go to a lot of different distributors, but other than Philips, I
> don't know of any parts.  All the distis I have checked only sell
> Philips parts in large quantities.  I guess I could ask for a few dozen
> samples.

Try the US-counterpart of Farnell: Digikey.
www.digikey.com
Do a search for the PCF8574AN and you'll find they have 415 in stock and
sell for $2.00 a piece.

Meindert

Lewin A.R.W. Edwards wrote:
>>have to buy a couple thousand minimum.  I am looking for a way to add 8
>>or 16 IOs.  Some chips are port expanders, some are LED drivers; either
>>will work if they come in small packages.  
> 
> 
> I2C is patented/copyrighted/trademarked. Look for '2-wire interface' parts, maybe.

Is '2-wire interface' always actually I2C, if avoiding the trademark issue?

I see a lot of SPI devices around - Would I be right in thinking that 
SPI is faster than I2C? Is it *better*?

ABS

Ralph Malph schrieb:
> 
> I looked around the web and could not find any sources of I2C port IO
> chips other than Philips.  Seems to get most of their I2C parts, you
> have to buy a couple thousand minimum.  I am looking for a way to add 8
> or 16 IOs.  Some chips are port expanders, some are LED drivers; either
> will work if they come in small packages.
> 
> So who else makes I2C chips?  A google search turned up lots of stuff,
> but no I2C makers.

As already mentioned, PCF8574 should be available in distribution.
(At least here in Europe, it is, in rather small quantities, and even
at hobby-electronic vendors.)

I2C is slower than other serial interfaces, but the advantages are
multi-master and fewest wires.
If you need cheap and rather fast I/O expansion, and have a few more
wires, try using simple shift registers ('165 for input, '595 for
output) - you can cascade them easily, and often you can share some
signals with other peripherals.

-- 
Dipl.-Ing. Tilmann Reh
Autometer GmbH Siegen - Elektronik nach Ma�.
http://www.autometer.de

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