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79641Re: [Electronics_101] Re: OPI-ONE cables again...

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  • Stefan Trethan
    Dec 13, 2012
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      If you go with the SPI/I2C IC, is there really any advantage to use the switch?
      I mean it would be like $10 to provide individual ICs, and those that
      take up to 4 diodes probably make it even cheaper.

      ST

      On Thu, Dec 13, 2012 at 11:09 PM, rtstofer <rstofer@...> wrote:
      > Measuring temperature with a diode is an old idea. But the semiconductor houses have taken it to a new level. You can buy a one-chip solution that handles ALL of the analog stuff and just presents the data over an I2C connection. Among many other devices is:
      > http://www.smsc.com/media/Downloads_Public/Data_Sheets/1402.pdf
      >
      > Some of the devices can handle up to 1500 ohms of series resistance and that's good because you would put an external analog switch in the circuit to select among the diodes.
      >
      > The advantage to this approach is pretty obvious: You don't have to understand a darn thing about analog electronics. You do have to get I2C working on some uC but this is usually included in some kind of library.
      >
      > Digikey has that chip for $1.42 in qty 1 so it might be worth an experiment or two. I could see building a PCB with the analog switch controlled by Arduino IO pins and the single temperature sensor. Or I might buy an SMD->DIP adapter and breadboard the thing. Just to see...
      >
      > Another nice device is the ON Semi NVT210 but I can't find a place to buy it in qty 1:
      > http://www.onsemi.com/pub_link/Collateral/NVT210-D.PDF
      >
      >
      > Richard
      >
      >
      >
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