I have written the testbench code and design code for Master-slave JK flip flop, but output isn't coming.
Please point out the error.
Test bench.sv
module JK_ff_tb;
reg clk;
reg reset;
reg j,k;
wire q;
wire qb;
jk_flip_flop_master_slave jkflipflop( .clk(clk), .reset(reset), .j(j), .k(k), .q(q), .q_bar(qb) );
initial begin
$dumpfile("dump.vcd"); $dumpvars;
$monitor(clk,j,k,q,qb,reset);
j = 1'b0;
k = 1'b0;
reset = 1;
clk=1;
#10
reset=0;
j=1'b1;
k=1'b0;
#100
reset=0;
j=1'b0;
k=1'b1;
#100
reset=0;
j=1'b1;
k=1'b1;
#100
reset=0;
j=1'b0;
k=1'b0;
#100
reset=1;
j=1'b1;
k=1'b0;
end
always #25 clk <= ~clk;
endmodule
Design.sv
module jk_flip_flop_master_slave(j,k,clk,reset,q,q_bar);
input j,k,clk,reset;
output q,q_bar;
reg q,q_bar; // Active low reset signal.
wire MQ; // The master's Q output.
wire MQn; // The master's Qn output.
wire Cn; // The clock input to the slave shall be the complement of the master's.
wire J1;
wire K1;
wire J2; // The actual input to the first SR latch (S).
wire K2; // The actual input to the first SR latch (R).
assign J2 = !reset ? 0 : J1; // Upon reset force J2 = 0
assign K2 = !reset ? 1 : K1; // Upon reset force K2 = 1
and(J1, j, q_bar);
and(K1, k, q);
not(Cn, clk);
sr_latch_gated master(MQ, MQn, clk, J2, K2);
sr_latch_gated slave(q, q_bar, Cn, MQ, MQn);
endmodule // jk_flip_flop_master_slave
Sr_Latched flip flop module
module sr_latch_gated(Q, Qn, G, S, R);
output Q;
output Qn;
input G;
input S;
input R;
wire S1;
wire R1;
and(S1, G, S);
and(R1, G, R);
nor(Qn, S1, Q);
nor(Q, R1, Qn);
endmodule // sr_latch_gated
I have coded the entire thing in EDA-playground.
The diagram generated was really abrupt as well.
If there is another logic that can be implemented easily, do tell.
I get compile errors on 2 different simulators. You should not declare q and q_bar as reg in the jk_flip_flop_master_slave module. You should delete this line:
reg q,q_bar; // Active low reset signal.
Then it compiles and simulates for me. I see this output:
100xx1
110xx0
010010
110010
010010
110010
101010
001010
101010
001010
...
Related
I've been designing a one-shot as part of my EE senior project and am unable to get the 'Reset' to toggle the output to 0.
I used the RTL_viewer in Quartus and the design does match my code: The DFF output (Q) is fed into 2 inverters then into the DFF Reset.
My understanding is that the two inverters should act as buffers. The DFF output should be 0 until the next clock edge is reached. I'm not sure if something is wrong with my design or if this is a timing error. I tried playing around with the clock speed and the buffer delay, but neither produced the correct results.
module oneShot(Clk, Q, Q_bar);
input Clk;
output Q, Q_bar;
logic X, Reset /* synthesis keep */;
logic D = 1'b1;
parameter propogation_delay = 30ns;
not #(propogation_delay) (X, Q);
not #(propogation_delay) (Reset, X);
//instantiation of flip flop
//DFF (Clk, Reset, D, Q);
DFF1 unit0 (Clk, Reset, D, Q);
assign Q_bar = ~ Q;
endmodule
module DFF1 (Clk, Reset, D, Q);
input Clk, Reset, D;
output logic Q;
always_ff #(posedge Clk)
begin
if(Reset == 1'b1)
Q <= 0;
else
Q <= D;
end
endmodule
module oneShot_tb;
logic Clk, Q, Q_bar, Reset;
oneShot DUT (Clk, Q, Q_bar);
always begin
Clk = 0;
#10;
Clk = 1'b1;
#10;
end
initial begin
#300;
$stop;
end
I am a beginner in designing circuit using verilog in modelsim. I use a sample code and a tutorial to learn how modelsim works. The code and the testbench are compiled without any problem and even testbench is simulated without any error but the input and output signals are not shown in object windows and they are not under instance menu. please describe for me how can I find them and simulate the waveforms.
here is my code and the test bench.
the definition of a D flipflop
// module D_FF with synchronous reset
module D_FF(q, d, clk, reset);
output q;
input d, clk, reset;
reg q;
// Lots of new constructs. Ignore the functionality of the
// constructs.
// Concentrate on how the design block is built in a top-down fashion.
always #(negedge clk or posedge reset)
if (reset)
q <= 1'b0;
else
q <= d;
endmodule
the definition of a T flipflop from D
module T_FF(q, clk, reset);
output q;
input clk, reset;
wire d;
D_FF dff0(q, d, clk, reset);
not n1(d, q);
endmodule
counter codes:
module rcc4(q, clk, reset);
output [3:0] q;
input clk, reset;
//4 instances of the module T_FF are created.
T_FF tff0(q[0],clk, reset);
T_FF tff1(q[1],q[0], reset);
T_FF tff2(q[2],q[1], reset);
T_FF tff3(q[3],q[2], reset);
endmodule
testbench code:
module stimulus();
reg clk;
reg reset;
wire[3:0] q;
// instantiate the design block
rcc4 r1(q, clk, reset);
// Control the clk signal that drives the design block. Cycle time = 10
initial
clk = 1'b0; //set clk to 0
always
#5 clk = ~clk; //toggle clk every 5 time units
// Control the reset signal that drives the design block
// reset is asserted from 0 to 20 and from 200 to 220.
initial
begin
reset = 1'b1;
#15 reset = 1'b0;
#180 reset = 1'b1;
#10 reset = 1'b0;
#20 $finish; //terminate the simulation
end
// Monitor the outputs
initial
$monitor($time, " Output q = %d", q);
endmodule
I am using modelsim 10.1c on Windows 10.
The following picture is from my project and it shows my object and instance window.
The switch -voptargs=+acc will solve your issue.
vsim -voptargs=+acc modulename
I want it to show the output of the flip flop but instead it lists the output as 'Z'. How can I get it to do this?
Code:
module d_flip_flop_edge_triggered(Q, Qn, C, D);
output Q;
output Qn;
input C;
input D;
wire Q;
wire Qn;
wire Cn;
wire Cnn;
wire DQ;
wire DQn;
not(Cn, C);
not(Cnn, Cn);
endmodule
This is the test bench - I think the problem lies here.
TestBench:
module ffTB;
// Inputs
reg C;
reg D;
// Outputs
wire Q;
wire Qn;
// Instantiate the Unit Under Test (UUT)
d_flip_flop_edge_triggered uut (
.Q(Q),
.Qn(Qn),
.C(C),
.D(D)
);
initial begin
// Initialize Inputs
C = 0;
D = 0;
// Wait 100 ns for global reset to finish
#100;
C = 1;
D = 1;
#100;
C = 0;
#100;
C = 1;
#100;
C = 0;
#100;
C = 1;
#100;
C = 0;
end
endmodule
Thank you my grade depends on it!
Your model for the flip-flop is completely wrong. (Sorry, but it's true.) With the exception of the input C, none of the inputs or outputs are connected to anything! As a result, the testbench shows that the outputs are floating, which is denoted by the value Z.
Your D flip-flop RTL,
module d_flip_flop_edge_triggered( output reg Q,
output wire Qn,
input wire clk,
input wire rst_n,
input wire D
);
always # (posedge clk or negedge rst_n)
begin
if (~rst_n)
begin
Q <= 1'b0;
end
else
begin
Q <= D;
end
end
assign Qn = ~Q;
endmodul
And Testbench,
module ffTB;
reg clk;
reg rst_n;
reg D;
wire Q, Qn;
d_flip_flop_edge_triggered d_flip_flop_edge_triggered_inst (Q, Qn, clk, rst_n, D);
initial
begin
clk = 1'b0;
rst_n = 1'b0;
D = 1'b0;
#10 rst_n = 1'b1;
#600 $finish;
end
always clk = #5 ~clk;
initial
begin
repeat (100)
begin
D = $random;
#5;
end
end
endmodule
with simulation,
This my Verilog code to convert the number x into form x=a0*R+a1 ,e.g 51 = 5*10 +1. My code does not work, it cannot enter the always loop.
`timescale 1ns / 1ps
module poly(
input [15:0] r,
input [15:0] x,
output reg[15:0] a1,
output reg [15:0] a0,
output finish,
input clk,
input reset
);
reg [15:0] sum;
assign finish =(sum > x);
always# (posedge clk )
begin
if(reset)
begin
a0 <=0;
sum <=0;
end
else if (!finish)
begin
a0 <=a0+1;
sum <= sum+r;
end
else
a1<=x-sum;
end
initial begin
$monitor ( "a1=%b,a0=%b,finish=%b,reset=%b",a1,a0,finish,reset);
end
endmodule
testbench
`timescale 1ns / 1ps
module tb_p;
reg [15:0] r;
reg [15:0] x;
wire[15:0] a1;
wire [15:0] a0;
wire finish;
reg clk;
reg reset;
initial clk=0;
always #5 clk=!clk;
poly m1(r,x,a1,a0,finish,clk,reset);
initial begin
r<=10;
x <=17;
#1 reset<=1;
#2 reset<=0;
end
endmodule
Since your reset signal is synchronous to the clock, you need to extend it so that it is high for at least one posedge of the clock:
initial begin
r<=10;
x <=17;
#1 reset<=1;
#20 reset<=0;
#500 $finish;
end
Note that I added $finish just so my simulation would end.
I want to write code in Verilog for a Ring Oscillator.
Here is my code:
module RingOsci(enable, w1, w2, w3);
input enable;
output w1, w2, w3;
wire w4;
and (w4, enable, w3);
not #2(w2, w1);
not #2(w3, w2);
not #2(w1, w4);
endmodule
But, W_i is always Z.
Here is my test bench:
module RingOsciTB();
reg en;
wire out1, out2, out3;
initial begin
en = 1'b0;
#20
en = 1'b1;
end
endmodule
How can I change the Z value and enable the Oscillator?
You need to add an instance of your design module in your testbench. For example:
module RingOsciTB();
reg en;
wire out1, out2, out3;
RingOsci dut (
// Inputs:
.enable (en),
// Outputs:
.w1 (out1),
.w2 (out2),
.w3 (out3)
);
initial begin
en = 1'b0;
#20
en = 1'b1;
end
endmodule