yannoo95170
Member level 1
Hi,
I just begin with FPGA development on a Linux box, and have a problem with the basic counter example
(the first thing that I have tested just after the standard beginner "Hello, World" example)
counter.vl
test.vl
This compile fine with iverilog on my Linux box using this makefile
but my problem is from the result of vvp test
I have tested to modify the
to values such as
or
and this make more occurences of the counter but **always** a reset of the counter's value at time 57
=> what the signification of the values after the # ?
(the # character does not seem to be one indication of a line of comment such as used into scripts shell)
[this seem to indicate a time + an action but I don't understand if the time is relative to previous "#steps" or global]
I just begin with FPGA development on a Linux box, and have a problem with the basic counter example
(the first thing that I have tested just after the standard beginner "Hello, World" example)
counter.vl
Code:
module counter(out, clk, reset);
parameter WIDTH = 8;
output [WIDTH-1 : 0] out;
input clk, reset;
reg [WIDTH-1 : 0] out;
wire clk, reset;
always @(posedge clk)
out <= out + 1;
always @reset
if (reset)
assign out = 0;
else
deassign out;
endmodule // countertest.vl
Code:
module test;
/* Make a reset that pulses once. */
reg reset = 0;
initial begin
# 17 reset = 1;
# 11 reset = 0;
# 29 reset = 1;
# 11 reset = 0;
# 100 $finish;
end
/* Make a regular pulsing clock. */
reg clk = 0;
always #5 clk = !clk;
wire [7:0] value;
counter c1 (value, clk, reset);
initial
$monitor("At time %t, value = %h (%0d)",
$time, value, value);
endmodule // testThis compile fine with iverilog on my Linux box using this makefile
Code:
all : hello test
hello : hello.vl
iverilog -o hello hello.vl
vvp hello
test : counter.vl test.vl
iverilog -o test counter.vl test.vl
vvp testbut my problem is from the result of vvp test
Code:
yannoo@Ubuntoo:~/dev/FPGA$ make test
iverilog -o test counter.vl test.vl
vvp test
At time 0, value = xx (x)
At time 17, value = 00 (0)
At time 35, value = 01 (1)
At time 45, value = 02 (2)
At time 55, value = 03 (3)
At time 57, value = 00 (0)
At time 75, value = 01 (1)
At time 85, value = 02 (2)
At time 95, value = 03 (3)
At time 105, value = 04 (4)
At time 115, value = 05 (5)
At time 125, value = 06 (6)
At time 135, value = 07 (7)
At time 145, value = 08 (8)
At time 155, value = 09 (9)
At time 165, value = 0a (10)I have tested to modify the
Code:
# 100 $finish;
Code:
# 1000 $finish;
Code:
# 5000 $finish;=> what the signification of the values after the # ?
(the # character does not seem to be one indication of a line of comment such as used into scripts shell)
[this seem to indicate a time + an action but I don't understand if the time is relative to previous "#steps" or global]
Last edited: