Problem with external sdram

Test_MSITel_RAM.zip

Hi all.

I am using an external SDRAM in my pcb.
In another pcb it works very well, but on this one it doesn't. I have noticed that the CAS signal on the card that is not working is extremely narrower.
The settings in the tx_application_define_user.c file are identical.
I probably forgot to set something.
I attach test project.

Best Regards

Paolo

  • Can that be a problem of SSP version? The one that works uses SSP 1.7.0, the new 1.7.5

    Thank you
  • In reply to Paolo Miatto:

    Hi Paolo-
    When you say extremely narrower- how much narrower? Is it within the spec for the CAS signal?
  • In reply to WarrenM:

    Hi WarrenM
    On the card that works it was about 100ns on the one that doesn't work about 1 ns. It's the only difference we've seen

    Thank you
    Paolo
  • In reply to Paolo Miatto:

    Hi Paolo-
    I would guess that 1ns is not in spec. Is the CAS output pin configured correctly? Do the boards have different BSPs?

    Also- Any chance there is a short on the CAS signal that would interfere with correct operation?
  • In reply to WarrenM:

    Hi Warrem
    We have not seen short circuits. The BSPs in both pcb are custom. The bus settings are different. In the previous pcb we used only the SDRAM and it was set in SDRAM 16 bit. In this new one it is set in custom because we use other CS, but the SDRAM pins are the same. Can it depend on that?

    Thanks
    Paolo
  • In reply to Paolo Miatto:

    Hi.
    I understand where the problem is. I lowered the sdram clock from 120MHz to 60Mhz and now the memory test works now. It is probably a pcb layout problem.

    Thank you
    Paolo