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Altera_Forum's avatar
Altera_Forum
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11 years ago

Altsyncram -read data

Hi, i have a problem to read data from an address ( i use the altsyncram block). For example i want to read the value 5 from the address 200. In the mif file i have fill with the number 5 , the space of address 200. I have also put pins in the altsyncram for the address and the data .In the waveform during the clock cycle which the read signal is 1, the result of the address is 200 when the clock goes from 0 to 1, but the data doesn't change. May i have to set a different value in fmax to the classic timing analyzer wizard or set a higher period or something else to change at the options?Generally, i am not an expert about the options ,quartus gives.

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    11 years ago

    'altsyncram' blocks typically have registers on their input signals and optionally on it's output signals. So, the value on 'q' won't be valid for up to 2 clock cycles after the address is presented.

    Could this explain what you're seeing?

    Cheers,

    Alex
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    11 years ago

    Thnx Alex, that reply was very helpful. Now, is there something that can i do in order not to have this delay, such as a memory block that quartus provide without these regs or something else?

    -Kostas-
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    11 years ago

    You don't state which device (family) you're using but typically the control signals are always registered going into the ram block. You have an option to register the output value.

    You could always just code it as a combinatorial block and let Quartus try and fit it for you...

    Happy New Year,

    Alex