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Old 10-26-2003, 08:15 AM
Bose
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Default Verilog Program With A Problem

Hi to all,

I'm writing a program using verilog at the moment. The program that
i'm doing now is one of many blocks that will be finally linked up
together...Right now, i'm having some problems with my program...In my
program, i have a part where i need to compare the input(eingated) &
an output(eout_prev) of another program which is a D flip flop. So in
my program what should i define "eout_prev" as? An input, output, reg
....?
I need help urgently. Anyone can help me out ?

Thanks a lot! :-)

Below is my program & the D flip flop program ,and i have pointed to
where my problem lies.


--------------------------------------------------------------------------------

`timescale 1ns/1ps

module encoder(eingated, clr, clk, keydet, inhibit, eout);

input [3:0]eingated;
input clr, clk;
output keydet, inhibit;
output [3:0]eout;
reg [3:0]eout;
reg keydet, inhibit;

parameter idle = 1'b0, keypressed = 1'b1;
reg [1:0] cur_state, next_state;
reg eout_prev;


always @(posedge clk or negedge clr)
begin
if(clr==0)
cur_state = idle;
else
cur_state = next_state;
end



[email protected](cur_state or eingated or eout or eout_prev)
begin
case(cur_state)
idle : if (eingated == 4'b1110 || eingated == 4'b1101 ||
eingated == 4'b1011 || eingated == 4'b0111)
begin
keydet = 1'b1;
inhibit = 1'b1;
next_state = keypressed;
end
else
begin
keydet = 1'b0;
inhibit = 1'b0;
next_state = idle;
end


keypressed : if (eingated == 4'b1110 || eingated == 4'b1101 ||
eingated == 4'b1011 || eingated == 4'b0111)
if (eout == eout_prev) <------- What to define
begin "eout_prev" as?
keydet = 1'b1;
inhibit = 1'b1;
next_state = keypressed;
end
else
begin
keydet = 1'b0;
inhibit = 1'b1;
next_state = idle;
end
else
begin
keydet = 1'b0;
inhibit = 1'b0;
next_state = idle;
end
endcase
end


always @(eingated)
begin
case (eingated)
4'b1110: eout = 2'b00;
4'b1101: eout = 2'b01;
4'b1011: eout = 2'b10;
4'b0111: eout = 2'b11;
default: eout = 2'b0;
endcase
end

endmodule


--------------------------------------------------------------------------------
Below is the program of the D flip flop with output "eout_prev" :



`timescale 1ns/1ps

module eoutTemp(eout, keydet, clear, eout_prev);

input [1:0] eout;
input keydet, clear;

output [1:0] eout_prev;
reg [1:0] eout_prev;

always @(posedge keydet or negedge clear)
if(clear==0)
eout_prev<=2'b0;
else eout_prev<={eout};

endmodule
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