AD7490 Interfacing with Microcontroller

Discussion in 'Embedded Systems and Microcontrollers' started by elabsp, Sep 22, 2014.

  1. elabsp

    Thread Starter New Member

    Oct 23, 2013
    13
    1
    Hi,

    I am facing some problem in Reading Analogue values from AD7490. I always received FF from ADC. If any one interface this ADC with 8 bit Microcontroller then please share your experience.

    Thanks
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,447
    3,363
    You will have to provide more information than that.
    Which microcontroller are you using?
    Show us your circuit schematic.
    Show us your code.
     
  3. elabsp

    Thread Starter New Member

    Oct 23, 2013
    13
    1
    Thanks MrChips

    I am using Microcontroller with 11.0592 MHz and connected with SPI pins I was confused due to arrangement of 12bit command word.
    According to the datasheet 12bit command word with 12th bit MSB (write) and LSB is Coding bit. However We have 16 bit integer so I m confused that either I need to send 0x8330 command byte or 0x08333 command byte.
     
  4. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,392
    1,606
    You send the command byte as you receive the last conversion. The first 12 bits hold the config data, the last 4 bits are all "don't care."

    And for a 16 bit conversion your received (incorrect) data should be 0xFFFF not just FF.
     
  5. elabsp

    Thread Starter New Member

    Oct 23, 2013
    13
    1
    Thanks issue is resolved. Problem is that I was not giving CS cycling after writing command byte.

    Again thanks
     
    ErnieM likes this.
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