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Analog multiplexor (possibly i2c)

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By Nicola
2008-09-29 19:27
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Hello! i have almost finished my analog inputs on my last project.. i have only one left and i need to attach some potentiometers to do some calibration.. I could really use some nice multiplexing. What i'd like is a chip with some analog inputs and possibly an i2c interface so that you can choose which analog pin to read and get a digital reading. Do you know if anything like this exists ?
‹ IR and pulsin Anyone have any experience with an ooPIC? ›
By robologist @ Mon, 2008-09-29 20:46
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A couple Mux's

I did a quick Google for "I2C analog multiplexer" which turned up this Analog ADG792A which might be a pain prototyping because of the surface mount package. There appear to be some others by Maxim, and NXP Philips further down the page.  Sparkfun has an easier to solder surface mount mux http://www.sparkfun.com/commerce/product_info.php?products_id=299 that also has boards to prototype with listed below it.

By BaseOverApex @ Mon, 2008-09-29 22:04
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Or do it the easy way...

Microchip will happily send you MCP3021 (10 bit) I2C ADC for free. Or the MCP3221 (12 bit).

I have samples of MCP4922, but it's SPI.
By Nicola @ Tue, 2008-09-30 07:55
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uhm i love free stuff :)but

uhm i love free stuff :)

but it appears to only have 1 input, or did i read wrong ? Also, fixed i2c address, and it doesn't look like it have those bended feet, not the standard good old pins ?

By BaseOverApex @ Tue, 2008-09-30 10:29
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Yes

Sadly these normally only have 1 or 2 ADCs per package.
By Nicola @ Tue, 2008-09-30 12:04
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ok.. i could live with

ok.. i could live with that.. but it should be at least breadboard friendly..

i hate non-DIP chip :P

By CaptainTuna @ Tue, 2008-09-30 19:24
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i have already read about

i have already read about the multiplexers, but have never seen them in action. Could you tell me how they work? I mean...how do you get to change the connection with an I2C?
By rik @ Wed, 2008-10-01 20:38
rik's picture

non-I2C multiplexer

David Cook (here he comes again!) wrote an excellent article about a bot that uses multiplexers. He saves on analogue inputs on his micro controller, but pays in digital outputs (three of them) for addressing the inputs on his mulitplexer(s). Very usable info!
By Nicola @ Mon, 2008-10-06 09:13
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i've found this one that

i've found this one that looks just right:

http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1890/t/al

 i'm applying for some free sample :P

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