Separate grounding for AI and DIO

Discussion in 'Embedded Systems and Microcontrollers' started by Anjanav, May 4, 2010.

  1. Anjanav

    Thread Starter New Member

    Mar 2, 2010
    16
    0
    Hi...

    How to give separate grounding for Analog Input and Digital Input/output:confused:
    Using pic18f4550....



    thanks...
     
  2. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
    Why do you need separate grounds?
     
  3. t06afre

    AAC Fanatic!

    May 11, 2009
    5,939
    1,222
    Separate grounds is separate in respect to the cabling or tracks on PCB. The different grounds must have a common reference point. Either on the board or at the power supply. It is somewhat complicated to give all details here. But this http://www.hottconsultants.com/pdf_files/june2001pcd_mixedsignal.pdf and this http://www.hottconsultants.com/pdf_files/ground.pdf may give you some info. both found here http://www.hottconsultants.com/papers.html
    I will also recommend the book "Electromagnetic Compatibility Engineering" or "Noise Reduction Techniques in Electronic Systems, 2nd edition" the latter is an older version of the first book. Both are written by Hyenry W. Ott. You can find "Electromagnetic Compatibility Engineering" on google books. The view is limited :(
     
    Last edited: May 4, 2010
  4. kingdano

    Member

    Apr 14, 2010
    377
    19
    A book i have read sections of called "The Circuit Designer's Companion" has a thorough section on grounding issues and common concerns/problems.

    Maybe give that a read.
     
  5. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234
    Here is how it is normally done, you want to keep all analog grounds connected together, and all digital grounds all connected, the only place both digital and analog ground should connect is near the power source to minimize noise in the analog section, I had to do this in my Electronic Drum Trigger project so I can keep all the analog mux grounds separate from all the uc grounds and only connected them near the 2 voltage regulators, this kept all my analog signals nice and clean, plus decoupling capacitors near all the IC's used also kept the noise out....

    EDRUM PSU PCB edit.jpg

    B. Morse
     
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