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Digital to Analog Converter — Parallax Forums

Digital to Analog Converter

HuskerHusker Posts: 15
edited 2009-05-05 20:41 in BASIC Stamp
I am using a BS2 and a AD694AQ to try an create a 4-20mA signal.· For the life of me I cannot get this to work.· After looking at the datasheets and trying many setups its obvious Im not doing this right.· Also this DAC does not use an 8 bit input pin system so Im not sure how to adjust the output.· Can anyone suggest a simple setup to for this IC and how·to adjust the output·up and down?· Thank you so much for any help.

Comments

  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2009-05-05 06:36
    The chip you cite is not a DAC. It's a voltage-to-current converter (current transmitter). You need to provide it with an analog voltage, either 0 to 2V or 0 to 10V, which it converts to a 4-20mA current.

    -Phil
  • stamptrolstamptrol Posts: 1,731
    edited 2009-05-05 18:54
    As Phil says, your chip will convert an analog input voltage into a current.

    Use the PWMOUT (with the resistor and capacitor) command as shown in the Help files to generate a voltage you can control.

    Cheers,

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Tom Sisk

    http://www.siskconsult.com
    ·
  • HuskerHusker Posts: 15
    edited 2009-05-05 19:01
    Oh okay. That actually will work better. So I just send a voltage input from 0-2v to the 2v pin? Aside from from the Iout what other pins do I need just to do the basic function? Thanks for the help.
  • stamptrolstamptrol Posts: 1,731
    edited 2009-05-05 20:41
    Page 5 of the data sheet shows the suggested minimum connections for the chip to work properly.

    Always assume the manufacturer knows how to use the chip!

    Cheers,

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Tom Sisk

    http://www.siskconsult.com
    ·
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