Forums

I2C port IO chips

Started by Ralph Malph January 21, 2004
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 --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.560 / Virus Database: 352 - Release Date: 08/01/04
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&#2013265951;. http://www.autometer.de ================================================================== In a world without walls and fences, who needs Windows and Gates ? (Sun Microsystems)