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Altera_Forum's avatar
Altera_Forum
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15 years ago

How to initialize 2-d memory?

Dear Forum,

I'd like to put a subsystem on a PLD which is a lookup table pretending to be the output of an ADC. I use the following verilog to initialize the lookup table.

`define W 10 /* ADC bit width */

`define N 40 /* modulo count */

reg [2*W-1:0] count_to_volt[0:N-1]/* synthesis ram_init_file = "memarray3.mif" */;

However, I'd really like 4 channels,

reg [2*W-1:0] count_to_volt_channel[0:3][0:N-1]/* synthesis What goes here? */;

but I don't know how to initialize the above 2-d memory array. At present my solution is just to use the first form four times with names count_to_volt1,...,count_to_volt4, but this is messy and it would be neater to use the 2-d memory. So, how do I persuade Quartus to initialize a 2-d memory?

Yours sincerely

Stephen

3 Replies

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

    Quartus can compreend farily sophisticated initial blocks.

    Something like this should do the trick:

    integer i, j;

    initial begin

    for(i = 0; i < 4; i = i+1) begin

    for(j = 0; j < N; j = j + 1) begin

    count_to_volt[i][j] = something

    end

    end

    end
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    Dear rbugalho,

    That's very interesting because I did not know that one could use initial blocks in Quartus. Is this a functionality that has recently been added? Hitherto, I had guessed that the reason for .mif files was because Quartus did not understand initial blocks.

    Yours sincerely

    Stephen
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    Dear rbugalho,

    Forget my last reply, I've just read the section entitled "Specifying Initial Memory Contents at Power-Up" in Volume I of the Quartus II handbook where it explains that Quartus can create a .mif file from an initial block for inferred memory.

    Yours sincerely

    Stephen