atifhashmi
Newbie level 3
Hi all,
I am hoping that this is the right forum to ask this question. I am trying to synthesize the code for a linear feedback shift register. The code is below
When I synthesize this deisgn, I get the following error message, multiple times.
However, in the above code when I replace
with
the warnings go away.
I am trying to understand what the warning is trying to tell me but have been unsuccessful. Is there are problem with using a 4-input xor?
I will really appreciate any comment or suggestion.
Thanks!!
I am hoping that this is the right forum to ask this question. I am trying to synthesize the code for a linear feedback shift register. The code is below
Code:
module lfsr_8bit(clk,op,seed,randVal);
input clk;
input [1:0] op; //defines the operation
input [7:0] seed;
output [7:0] randVal;
reg [7:0] randVal;
wire linearFeedback;
assign linearFeedback = randVal[7]^randVal[5]^randVal[4]^randVal[3];
always@(posedge clk)
begin
case(op)
2'b00: randVal <= 8'b0;
2'b01: randVal <= seed;
2'b10: randVal <= {linearFeedback,randVal[7:1]};
default: begin
//do nothing
end
endcase
end
endmoduleWhen I synthesize this deisgn, I get the following error message, multiple times.
Code:
No driver for fanout pin randVal[7]/DHowever, in the above code when I replace
Code:
assign linearFeedback = randVal[7]^randVal[5]^randVal[4]^randVal[3];with
Code:
assign linearFeedback = randVal[7]^randVal[5];the warnings go away.
I am trying to understand what the warning is trying to tell me but have been unsuccessful. Is there are problem with using a 4-input xor?
I will really appreciate any comment or suggestion.
Thanks!!