Unable to Infer M9K in Quartus

[GDagi1]

Hi all,

I borrowed some code from a Xilinx project, where RAM was inferred successfully. I would like to do the same in my Quartus 18.1 project with my MAX10 FPGA DevKit. Here's both methods of inferring I have attempted:

reg [(DWIDTH-1):0] mem [(1<<AWIDTH)-1:0] /* synthesis ramstyle = M9K */;

(* ramstyle = "M9K" *) reg [(DWIDTH-1):0] mem [(1<<AWIDTH)-1:0];

Neither of which throw any errors or warnings (searched Quartus console).

I have also checked the resource utilization report, and see Logic Cells (~10,000) / Dedicated Logic Registers (~8000) being used rather than M9Ks (0).

Thanks in advance!

[sstrell]

Where is the code for how the RAM is to operate?  If you don't code the RAM properly, it's not going to get inferred into a RAM block.

[GDagi1]

always@(posedge clk) begin
    if(rst) begin
        // set things to 0
    end

    else begin
        if((|wea_r) && wr_ena_r) begin
            for (i = 0; i < (DWIDTH/8); i=i+1) begin
                if (wea_r[i]) begin
                    for (j = 0; j < 8; j = j + 1) begin
                        mem[wr_addr_r][(8*i)+j] <= data_in_r[(8*i)+j] && wea_r[i];
                    end
                end
            end
        end

        if (rd_ena)
            data_out_r <= mem[rd_addr_r];
        else
            data_out_r <= 0;
        end
end

[ak6dn · Accepted solution]

Your code for the memory block itself is way too complicated for Quartus to infer it from block rams.

You need to look at the verilog templates that Quartus supplies for inferred memory.

Here is what I use and it infers as block ram (M9K, M4K depending) just fine.

Note  addr, mdi, mwr are wire type; mdo are reg type.

reg [0:11] memory [0:MEMSIZE-1] /* synthesis ramstyle = "no_rw_check" */;

always @(posedge clk)
      begin
            if (mwr) memory[addr] <= #TPD mdi;
            mdo <= #TPD memory[addr];
      end

[GDagi1]

Yep, this seemed to be it. I switched to the Quartus template and it worked.

[RichardTanSY_Intel]

Hi, 

I’m glad that your question has been addressed, I now transition this thread to community support. If you have a new question, feel free to open a new thread to get the support from Intel experts. Otherwise, the community users will continue to help you on this thread. Thank you.

Best Regards,

Shyan Yew