Spartan 2 & 3, serial config and CS pin

Discussion in 'Embedded Systems and Microcontrollers' started by aleksazr, May 17, 2010.

  1. aleksazr

    Thread Starter New Member

    May 16, 2010
    14
    0
    Spartan 2 docs clearly says that, even though
    you are configuring the FPGA in serial mode,
    you should keep CS pin high.

    What about Spartan 3?

    I don't see something like:
    "Yes, Spartan 2 had an error, but it has been fixed in Spartan 3"
     
  2. aleksazr

    Thread Starter New Member

    May 16, 2010
    14
    0
    OK, when I build my board, I will toggle CS pin (with active WR)
    during serial config and will write here.
     
  3. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
    Im sure others are wondering the same thing.

    I do not know if there was a change between 2 and 3. Posting your results when you find out would be good of you.
     
  4. aleksazr

    Thread Starter New Member

    May 16, 2010
    14
    0
    I will post, but it will take some weeks... sorry.
     
  5. aleksazr

    Thread Starter New Member

    May 16, 2010
    14
    0
    Here I am!

    Well, I did say "some weeks"... (ad infinitum) Am I slow or what?

    I've finally done the tests, but with Spartan 3A, not Spartan 3.

    First of all, PUDC = 0. (pull-ups during configuration are activated)

    1. CS = WR = 0;
    throughout the configuration, both CS and WR were constantly 0.

    2. CS = 0; WR = toggling;
    CS was 0, WR was toggling. (the same as DIN input, actually)

    3. CS = WR = toggling;
    both CS and WR were the same as DIN.

    4. CS = WR = floating;
    both pins on FPGA were disconnected.

    Result:
    Spartan3A was successfully configured in all tests. :)
     
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