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Carlos0u0
Visitor
Visitor
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Registered: ‎04-05-2021

Xst:2999 - Signal 'rom_0_0_0', unconnected in block 'rom0_0_0', is tied to its initial value.

Why do I encounter this problem?Or can I ignore this message?

`timescale 1ns / 1ps

module rom0_0_0(out,addr,command,clk_match,enable,select_mod);
output out;
input addr,clk_match,enable,select_mod,command;

parameter ROM_WIDTH = 36;
parameter ROM_ADDR_BITS = 9;//2^n can cover the amount of this stage

(* ROM_STYLE="BLOCK" *) //(* ROM_STYLE="DISTRIBUTED" *) or (* ROM_STYLE="AUTO" *)
reg [ROM_WIDTH-1:0] rom_0_0_0 [511:0];
reg [ROM_WIDTH-1:0] out;


wire [ROM_ADDR_BITS-1:0] addr;
wire [1:0] command;
wire select_mod;

initial
$readmemb("Data/Module0/StageR1_0", rom_0_0_0, 0, 511);//0~ n-1 for the amount

always @(posedge clk_match)
begin
    if (enable)
    begin
        if (command==2'b00)
        begin
            if(select_mod==1'b1)
            begin
                out <= rom_0_0_0[addr];
            end
            else
            begin
                out <= 0;
            end
        end
    end
end

endmodule

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4 Replies
varunra
Xilinx Employee
Xilinx Employee
140 Views
Registered: ‎01-24-2017

hi @Carlos0u0,

I am quite not sure which version of vivado you are using. 
the message you mentioned is it a warning or error or critical warning ???
I tried the above mentioned code and its tools was inferring Block ram. 

Make sure the mem file correctly. missing mem file may lead to the issue

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Carlos0u0
Visitor
Visitor
138 Views
Registered: ‎04-05-2021

hi @varunra 

Thank you for your reply.
The tool I use is ISE 14. 7.
The above message is just a warning.
And I also confirmed that the mem file is in the file path. So I want to ask if this warning can be ignored?

 

 

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varunra
Xilinx Employee
Xilinx Employee
114 Views
Registered: ‎01-24-2017

HI Carlos0u0,

I am using the same version of ISE. The only difference between your code and my code is, I have given the complete path path to my the mem file. 

Can you try the following.
1. If you are using a xst project try copying the mem file to the location where the the design file(i.e both the design file and mem file should be in same directory) is and just give the mem filename like
$readmemb("<memfile_name>", rom_0_0_0, 0, 511);//0~ n-1 for the amount.

2. is this is not possible try giving the absolute path in $readmemb command.

 

Let me know if that helps

Thanks

 

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Carlos0u0
Visitor
Visitor
73 Views
Registered: ‎04-05-2021

hi @varunra 

Thank you for your reply, I will try your method.
If it is useful, I will reply to you again.

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