标签：
FPGA 时序仿真
我刚刚编的程序，终于学会怎样进行时序仿真的，可是谁知道功能仿真是正确的，时序仿真的时候确没有输出结果，我把我的源代码传上来，肯请高手们帮我看一下我应该从那找错！
源代码：
/*It is a program of series input data to parallel out data,
which is used in 16DAPSK*/
`timescale 1us/1ns
module series_to_parallel(series_in,
convert_clk,
out_clk,
convert_rst,
parallel_out,
convert_out,
convert_begin,
busy);
input series_in;
input convert_clk;
input out_clk;
input convert_rst;
input convert_begin;
output[3:0] parallel_out;
output[3:0] convert_out;
output busy;
reg[3:0] parallel_out;
reg[3:0] convert_out;
reg busy;
reg [5:0] shift_state;
//reg convert_begin;
parameter shift_state_begin="6"'b100000;
parameter shift_state_bit0=6'b000010;
parameter shift_state_bit1=6'b000100;
parameter shift_state_bit2=6'b001000;
parameter shift_state_bit3=6'b010000;
parameter shift_state_end= 6'b000001;
always @(posedge convert_rst or posedge convert_clk)
begin
if(convert_rst)
begin
//busy<=1'b1;
//convert_begin<=1'b1;
if(convert_begin)
begin
shift_state<=shift_state_begin;
parallel_out<=4'b0000;
end
else
begin
shift_state<=shift_state_end;
parallel_out<=4'b0000;
end
end
else
begin
case(shift_state)
shift_state_begin:
begin
if(convert_begin)
begin
shift_state<=shift_state_bit3;
busy<=1'b1;
end
else
begin
shift_state<=shift_state_end;
busy<=1'b0;
end
end
shift_state_bit3:
begin
if(convert_begin)
begin
parallel_out[3]<=series_in;
shift_state<=shift_state_bit2;
busy<=1'b1;
end
else
begin
shift_state<=shift_state_end;
busy<=1'b0;
end
end
shift_state_bit2:
begin
if(convert_begin)
begin
parallel_out[2]<=series_in;
shift_state<=shift_state_bit1;
busy<=1'b1;
end
else
begin
shift_state<=shift_state_end;
busy<=1'b0;
end
end
shift_state_bit1:
begin
if(convert_begin)
begin
parallel_out[1]<=series_in;
shift_state<=shift_state_bit0;
busy<=1'b1;
end
else
begin
shift_state<=shift_state_end;
busy<=1'b0;
end
end
shift_state_bit0:
begin
if(convert_begin)
begin
parallel_out[0]<=series_in;
shift_state<=shift_state_bit3;
busy<=1'b1;
end
else
begin
shift_state<=shift_state_end;
busy<=1'b0;
end
end
shift_state_end:
begin
if(convert_begin)
begin
shift_state<=shift_state_begin;
busy<=1'b1;
end
else
begin
shift_state<=shift_state_end;
busy<=1'b0;
end
end
default:
begin
shift_state<=shift_state_end;
//convert_begin<=1'b0;
end
endcase
end
//busy<=1'b0;
end
//?????????1/4??????
always@(posedge out_clk or posedge convert_rst)
begin
if(convert_rst)
convert_out<=4'b0000;
else
convert_out<=parallel_out;
end
endmodule
testbench代码：
`timescale 1us/1ns //时间单位为500ns，不知道那个精度时间是什么意思
module test_series_to_pallel;
//`include "series_to_parallel.v"
reg test_series_in;
reg test_convert_clk;
reg test_convert_rst;
reg out_clk;
wire[3:0] test_parallel_out;
wire[3:0] convert_out;
reg convert_begin;
wire test_busy;
parameter half_period="1";
initial
begin
test_convert_clk="0";
out_clk="0";
end
initial
begin
#1 test_convert_rst="1";
#1 test_convert_rst="0";
end
initial
begin
#1 convert_begin="1";
#400 convert_begin="0";
end
always #half_period test_convert_clk=~test_convert_clk;
always #4 out_clk=~out_clk;
always @(negedge test_convert_clk)
begin
test_series_in={$random}%2;
end
series_to_parallel test_series_to_parallel(.series_in(test_series_in),
.convert_clk(test_convert_clk),
.out_clk(out_clk),
.convert_rst(test_convert_rst),
.parallel_out(test_parallel_out),
.convert_out(convert_out),
.convert_begin(convert_begin),
.busy(test_busy));
endmodule
全编译的时候出现的警告：
Warning: Verilog HDL Always Construct warning at series_to_parallel.v(37): variable "convert_begin" is read inside the Always Construct but isn't in the Always Construct's Event Control
Warning: Timing Analysis found one or more latches implemented as combinational loops
Warning: Node "shift_state.shift_state_end~7" is a latch
Warning: Found pins functioning as undefined clocks and/or memory enables
Info: Assuming node "convert_clk" is an undefined clock
Info: Assuming node "out_clk" is an undefined clock
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