HDLBits全部解答
文章目录
-
- Getting Started
-
- step_one
- Zero
- Verilog Language
-
- Basics
-
- Wire
- Wire4
- Notgate
- Andgate
- Norgate
- Xnorgate
- Wire decl
- 7458
- Vectors
-
- Vector0
- Vector1
- Vector2
- Vectorgates
- Gates4
- Vector3
- Vectorr
- Vector4
- Vector5
- Modules Hierarchy
-
- Module
- Module pos
- Module name
- Module shift
- Module shift8
- Module add
- Module fadd
- Module cseladd
- Module addsub
- Procedures
-
- Alwaysblock1
- Alwaysblock2
- Always if
- Always if2
- Always case
- Always case2
- Always casez
- Always nolatches
- More Verilog Features
-
- Conditional
- Reduction
- Gates100
- Vector100r
- Popcount255
- Adder100i
- Bcdadd100
- Circuits
-
- Combinational Logic
-
- Basic Gates
-
- m2014 q4h
- m2014 q4i
- m2014 q4e
- m2014 q4f
- m2014 q4g
- Gates
- 7420
- Truthtable1
- Mt2015 eq2
- Mt2015 q4a
- Mt2015 q4b
- Mt2015 q4
- Ringer
- Thermostat
- Popcount3
- Gatesv
- Gatesv100
- Multiplexers
-
- Mux2to1
- Mux2to1v
- Mux9to1v
- Mux256to1
- Mux256to1v
- Arithmetic Circuits
-
- Hadd
- Fadd
- Adder3
- m2014 q4j
- ece241 2014 q1c
- Adder100
- Bcdadd4
- Karnaugh Map to Circuit
-
- Kmap1
- Kmap2
- Kmap3
- Kmap4
- ece241 2013 q2
- m2014 q3
- 2012 q1g
- ece241 2014 q3
- Sequential Logic
-
- Latches and Flip-Flops
-
- Dff
- Dff8
- Dff8r
- Dff8p
- Dff8ar
- Dff16e
- m2014 q4a
- m2014 q4b
- m2014 q4c
- m2014 q4d
- Mt2015 muxdff
- 2014 q4a
- ece241 2014 q4
- ece241 2013 q7
- Edgedetect
- Edgedetect2
- Edgecapture
- Dualedge
- Counters
-
- Count15
- Count10
- Count1to10
- Countslow
- ece241 2014 q7a
- ece241 2014 q7b
- Countbcd
- Count clock
- Shift Registers
-
- Shift4
- Rotate100
- Shift18
- Lfsr5
- Mt2015 lfsr
- Lfsr32
- m2014 q4k
- 2014 q4b
- ece241 2013 q12
- More Circuits
-
- Rule90
- Rule110
- Conwaylife
- Finite State Machines
-
- Fsm1
- Fsm1s
- Fsm2
- Fsm2s
- Fsm3comb
- Fsm3onehot
- Fsm3
- Fsm3s
- ece241 2013 q4
- Lemmings1
- Lemmings2
- Lemmings3
- Lemmings4
- Fsm onehot
- Fsm ps2
- Fsm ps2data
- Fsm serial
- Fsm serialdata
- Fsm serialdp
- Fsm hdlc
- ece241 2013 q8
- ece241 2014 q5a
- ece241 2014 q5b
- 2014 q3fsm
- 2014 q3bfsm
- 2014 q3c
- m2014 q6b
- m2014 q6c
- m2014 q6
- 2012 q2fsm
- 2012 q2b
- 2013 q2afsm
- 2013 q2bfsm
- Building Larger Circuits
-
- review2015 count1k
- review2015 shiftcount
- review2015 fsmseq
- review2015 fsmshift
- review2015 fsm
- review2015 fancytimer
- review2015 fsmonehot
- Verification: Reading Simulations
-
- Finding bugs in code
-
- Bugs mux2
- Bugs nand3
- Bugs mux4
- Bugs addsubz
- Bugs case
- Building a circuit from a simulation waveform
-
- circuit1
- circuit2
- circuit3
- circuit4
- circuit5
- circuit6
- circuit7
- circuit8
- circuit9
- circuit10
- Verfication: Writing Testbenches
-
- clock
- tb1
- and
- tb2
- tff
- 最后
Getting Started
step_one
module top_module( output one );
// Insert your code here
assign one = 1'b1;
endmodule
Zero
module top_module(
output zero
);// Module body starts after semicolon
assign zero = 1'b0;
endmodule
Verilog Language
Basics
Wire
module top_module( input in, output out );
assign out = in;
endmodule
Wire4
module top_module(
input a,b,c,
output w,x,y,z );
assign w = a;
assign x = b;
assign y = b;
assign z = c;
endmodule
Notgate
module top_module( input in, output out );
assign out = ~in;
endmodule
Andgate
module top_module(
input a,
input b,
output out );
assign out = a && b;
endmodule
Norgate
或非门（英语：NOR gate）是数字逻辑电路中的基本元件，实现逻辑或非功能。有多个输入端，1个输出端，多输入或非门可由2输入或非门和反相器构成。
只有当两个输入A和B为低电平（逻辑0）时输出为高电平（逻辑1）。也可以理解为任意输入为高电平（逻辑1），输出为低电平（逻辑0）。
module top_module(
input a,
input b,
output out );
//或非门（英语：NOR gate）是数字逻辑电路中的基本元件，实现逻辑或非功能。
//有多个输入端，1个输出端，多输入或非门可由2输入或非门和反相器构成。
//只有当两个输入A和B为低电平（逻辑0）时输出为高电平（逻辑1）。也可以理解为任意输入为高电平（逻辑1），输出为低电平（逻辑0）。
assign out = ((a == 1'b0) && (b == 1'b0) ) ? 1'b1 : 1'b0;
endmodule
Xnorgate
module top_module(
input a,
input b,
output out );
//同或门（英语：XNOR gate或equivalence gate）也称为异或非门，
//在异或门的输出端再加上一个非门就构成了异或非门，是数字逻辑电路的基本单元，有2个输入端、1个输出端。
//当2个输入端中有且只有一个是低电平（逻辑0）时，输出为低电平。亦即当输入电平相同时，输出为高电平（逻辑1）。
assign out = (a == b) ? 1'b1 :1'b0;
endmodule
同或门（英语：XNOR gate或equivalence gate）也称为异或非门，
在异或门的输出端再加上一个非门就构成了异或非门，是数字逻辑电路的基本单元，有2个输入端、1个输出端。
当2个输入端中有且只有一个是低电平（逻辑0）时，输出为低电平。亦即当输入电平相同时，输出为高电平（逻辑1）。
Wire decl
//`default_nettype none
module top_module(
input a,
input b,
input c,
input d,
output out,
output out_n );
wire first;
wire second;
assign first = a && b;
assign second = c && d;
assign out = first || second;
assign out_n = ~out;
endmodule
7458
module top_module (
input p1a, p1b, p1c, p1d, p1e, p1f,
output p1y,
input p2a, p2b, p2c, p2d,
output p2y );
wire wire1;
wire wire2;
wire wire3;
wire wire4;
assign wire1 = p2a && p2b;
assign wire2 = p2c && p2d;
assign p2y = wire1 || wire2;
assign wire3 = p1a && p1b && p1c;
assign wire4 = p1f && p1e && p1d;
assign p1y = wire3 || wire4;
endmodule
Vectors
Vector0
module top_module (
input wire [2:0] vec,
output wire [2:0] outv,
output wire o2,
output wire o1,
output wire o0 ); // Module body starts after module declaration
assign outv = vec;
assign o0 = vec[0];
assign o1 = vec[1];
assign o2 = vec[2];
endmodule
Vector1
`default_nettype none // Disable implicit nets. Reduces some types of bugs.
module top_module(
input wire [15:0] in,
output wire [7:0] out_hi,
output wire [7:0] out_lo );
assign out_hi = in[15:8];
assign out_lo = in[7:0];
endmodule
Vector2
module top_module(
input [31:0] in,
output [31:0] out );//
// assign out[31:24] = ...;
assign out[31:24] = in[7:0];
assign out[23:16] = in[15:8];
assign out[15:8] = in[23:16];
assign out[7:0] = in[31:24];
endmodule
Vectorgates
module top_module(
input [2:0] a,
input [2:0] b,
output [2:0] out_or_bitwise,
output out_or_logical,
output [5:0] out_not
);
assign out_or_bitwise = a | b;
assign out_or_logical = a || b;
assign out_not[5:3] = ~b;
assign out_not[2:0] = ~a;
endmodule
Gates4
module top_module(
input [3:0] in,
output out_and,
output out_or,
output out_xor
);
assign out_and = in[3] & in[2] & in[1] & in[0] ;
assign out_or = in[3] | in[2] | in[1] | in[0] ;
assign out_xor = (in[3] == in[2] == in[1] == in[0]) ? 1'b0 : 1'b1;
endmodule
Vector3
module top_module (
input [4:0] a, b, c, d, e, f,
output [7:0] w, x, y, z );//
// assign { ... } = { ... };
assign w = {a,b[4:2]};
assign x = {b[1:0],c,d[4]};
assign y = {d[3:0],e[4:1]};
assign z = {e[0],f,2'b11};
endmodule
Vectorr
module top_module(
input [7:0] in,
output [7:0] out
);
assign out = {in[0],in[1],in[2],in[3],in[4],in[5],in[6],in[7]};
endmodule
// I know you're dying to know how to use a loop to do this:
//Create a combinational always block. This creates combinational logic that computes the same result
//as sequential code. for-loops describe circuit *behaviour*, not *structure*, so they can only be used
//inside procedural blocks (e.g., always block).
//The circuit created (wires and gates) does NOT do any iteration: It only produces the same result
//AS IF the iteration occurred. In reality, a logic synthesizer will do the iteration at compile time to
//figure out what circuit to produce. (In contrast, a Verilog simulator will execute the loop sequentially
//during simulation.)
//always @(*) begin
// for (int i=0; i<8; i++) // int is a SystemVerilog type. Use integer for pure Verilog.
// out[i] = in[8-i-1];
//end
//It is also possible to do this with a generate-for loop. Generate loops look like procedural for loops,
//but are quite different in concept, and not easy to understand. Generate loops are used to make instantiations
//of "things" (Unlike procedural loops, it doesn't describe actions). These "things" are assign statements,
//module instantiations, net/variable declarations, and procedural blocks (things you can create when NOT inside
//a procedure). Generate loops (and genvars) are evaluated entirely at compile time. You can think of generate
//blocks as a form of preprocessing to generate more code, which is then run though the logic synthesizer.
//In the example below, the generate-for loop first creates 8 assign statements at compile time, which is then
//synthesized.
//Note that because of its intended usage (generating code at compile time), there are some restrictions
//on how you use them. Examples: 1. Quartus requires a generate-for loop to have a named begin-end block
//attached (in this example, named "my_block_name"). 2. Inside the loop body, genvars are read only.
//generate
// genvar i;
// for (i=0; i<8; i = i+1) begin: my_block_name
// assign out[i] = in[8-i-1];
// end
//endgenerate
Vector4
module top_module (
input [7:0] in,
output [31:0] out );//
// assign out = { replicate-sign-bit , the-input };
assign out ={{24{in[7]}},in};
endmodule
Vector5
module top_module (
input a, b, c, d, e,
output [24:0] out );//
// The output is XNOR of two vectors created by
// concatenating and replicating the five inputs.
// assign out = ~{ ... } ^ { ... };
assign out = ~{{5{a}},{5{b}},{5{c}},{5{d}},{5{e}}} ^ {{5{a,b,c,d,e}}};
endmodule
Modules Hierarchy
Module
module top_module ( input a, input b, output out );
mod_a instance2 (
.out(out),
.in1(a),
.in2(b)
);
endmodule
Module pos
module top_module (
input a,
input b,
input c,
input d,
output out1,
output out2
);
mod_a u_mod_a(
out1,
out2,
a,
b,
c,
d
);
endmodule
Module name
module top_module (
input a,
input b,
input c,
input d,
output out1,
output out2
);
mod_a u_mod_a(
.out1(out1),
.out2(out2),
.in1(a),
.in2(b),
.in3(c),
.in4(d)
);
endmodule
Module shift
module top_module ( input clk, input d, output q );
wire wire1;
wire wire2;
my_dff my_dff_1(
.clk(clk),
.d(d),
.q(wire1)
);
my_dff my_dff_2(
.clk(clk),
.d(wire1),
.q(wire2)
);
my_dff my_dff_3(
.clk(clk),
.d(wire2),
.q(q)
);
endmodule
Module shift8
module top_module (
input clk,
input [7:0] d,
input [1:0] sel,
output [7:0] q
);
wire [7:0] wire1;
wire [7:0] wire2;
wire [7:0] wire3;
my_dff8 my_dff8_u1(
.clk(clk),
.d(d),
.q(wire1)
);
my_dff8 my_dff8_u2(
.clk(clk),
.d(wire1),
.q(wire2)
);
my_dff8 my_dff8_u3(
.clk(clk),
.d(wire2),
.q(wire3)
);
always @( *) begin
case (sel)
2'd0:q <= d;
2'd1:q <= wire1;
2'd2:q <= wire2;
2'd3:q <= wire3;
endcase
end
endmodule
Module add
module top_module(
input [31:0] a,
input [31:0] b,
output [31:0] sum
);
wire [15:0] low;
wire [15:0] heigh;
wire wire1;
add16 add16_low(
.a(a[15:0]),
.b(b[15:0]),
.cin(1'b0),
.sum(low),
.cout(wire1)
);
add16 add16_heigh(
.a(a[31:16]),
.b(b[31:16]),
.cin(wire1),
.sum(heigh),
.cout()
);
assign sum = {heigh,low};
endmodule
Module fadd
module top_module (
input [31:0] a,
input [31:0] b,
output [31:0] sum
);//
wire [15:0] low;
wire [15:0] heigh;
wire wire1;
add16 add16_low(
.a(a[15:0]),
.b(b[15:0]),
.cin(1'b0),
.sum(low),
.cout(wire1)
);
add16 add16_heigh(
.a(a[31:16]),
.b(b[31:16]),
.cin(wire1),
.sum(heigh),
.cout()
);
assign sum = {heigh,low};
endmodule
module add1 ( input a, input b, input cin, output sum, output cout );
// Full adder module here
/*
reg sum1;
reg cout1;
always @( *) begin
case (a + b + cin)
1'b0:begin
cout1 <= 1'b0;
sum1 <= 1'b0;
end
1'b1:
begin
cout1 <= 1'b0;
sum1 <= 1'b1;
end
2'b10:
begin
cout1 <= 1'b1;
sum1 <= 1'b0;
end
2'b11:
begin
cout1 <= 1'b1;
sum1 <= 1'b1;
end
endcase
end
assign sum = sum1;
assign cout = cout1;*/
//Full adder equations:
assign sum = a ^ b ^ cin;//位异或，加法器可以用异或来实现
assign cout = a&b | a&cin | b&cin;
//太复杂了，直接位运算就好了
endmodule
Module cseladd
module top_module(
input [31:0] a,
input [31:0] b,
output [31:0] sum
);
wire [15:0] low;
wire [15:0] heigh1;
wire [15:0] heigh2;
wire wire1;
add16 add16_low(
.a(a[15:0]),
.b(b[15:0]),
.cin(1'b0),
.sum(low),
.cout(wire1)
);
add16 add16_heigh0(
.a(a[31:16]),
.b(b[31:16]),
.cin(1'b0),
.sum(heigh1),
.cout()
);
add16 add16_heigh1(
.a(a[31:16]),
.b(b[31:16]),
.cin(1'b1),
.sum(heigh2),
.cout()
);
assign sum = (wire1) ? {heigh2,low} : {heigh1,low};
endmodule
Module addsub
module top_module(
input [31:0] a,
input [31:0] b,
input sub,
output [31:0] sum
);
wire [31:0] new_b;
wire [15:0] low;
wire [15:0] heigh;
wire wire1;
assign new_b = (sub == 1'b1) ? ((~b) + 1'b1) : (b);//补码
add16 add16_low(
.a(a[15:0]),
.b(new_b[15:0]),
.cin(1'b0),
.sum(low),
.cout(wire1)
);
add16 add16_heigh(
.a(a[31:16]),
.b(new_b[31:16]),
.cin(wire1),
.sum(heigh),
.cout()
);
assign sum = {heigh,low};
endmodule
Procedures
Alwaysblock1
// synthesis verilog_input_version verilog_2001
module top_module(
input a,
input b,
output wire out_assign,
output reg out_alwaysblock
);
assign out_assign = a & b;
always @( *) begin
out_alwaysblock <= a & b;
end
endmodule
Alwaysblock2
// synthesis verilog_input_version verilog_2001
module top_module(
input clk,
input a,
input b,
output wire out_assign,
output reg out_always_comb,
output reg out_always_ff );
assign out_assign = a ^ b;
always @( *) begin
out_always_comb <= a ^ b;
end
always @(posedge clk) begin
out_always_ff <= a ^b;
end
endmodule
Always if
// synthesis verilog_input_version verilog_2001
module top_module(
input a,
input b,
input sel_b1,
input sel_b2,
output wire out_assign,
output reg out_always );
assign out_assign = ((sel_b1 == 1'b1) && (sel_b2 == 1'b1)) ? b : a;
always @( *) begin
if ((sel_b1 == 1'b1) && (sel_b2 == 1'b1)) begin
out_always <= b;
end
else
out_always <= a;
end
endmodule
Always if2
// synthesis verilog_input_version verilog_2001
module top_module (
input cpu_overheated,
output reg shut_off_computer,
input arrived,
input gas_tank_empty,
output reg keep_driving ); //
always @(*) begin
if (cpu_overheated)
shut_off_computer = 1;
else
shut_off_computer = 0;
end
always @(*) begin
if (~arrived)
keep_driving = ~gas_tank_empty;
else
keep_driving = 0;
end
endmodule
Always case
// synthesis verilog_input_version verilog_2001
module top_module (
input [2:0] sel,
input [3:0] data0,
input [3:0] data1,
input [3:0] data2,
input [3:0] data3,
input [3:0] data4,
input [3:0] data5,
output reg [3:0] out );//
always@(*) begin // This is a combinational circuit
case(sel)
3'd0:
out <= data0;
3'd1:
out <= data1;
3'd2:
out <= data2;
3'd3:
out <= data3;
3'd4:
out <= data4;
3'd5:
out <= data5;
default :
out <= 4'b0;
endcase
end
endmodule
Always case2
// synthesis verilog_input_version verilog_2001
module top_module (
input [3:0] in,
output reg [1:0] pos );
always @( *) begin
casez (in[3:0])
4'b0000:
pos = 2'd0;
4'bzzz1:
pos = 2'd0;
4'bzz1z:
pos = 2'd1;
4'bz1zz:
pos = 2'd2;
4'b1zzz:
pos = 2'd3;
default :
pos <= 2'd0;
endcase
end
endmodule
Always casez
// synthesis verilog_input_version verilog_2001
module top_module (
input [7:0] in,
output reg [2:0] pos );
always @( *) begin
casez (in)
8'bzzzzzzz1:pos = 3'd0;
8'bzzzzzz1z:pos = 3'd1;
8'bzzzzz1zz:pos = 3'd2;
8'bzzzz1zzz:pos = 3'd3;
8'bzzz1zzzz:pos = 3'd4;
8'bzz1zzzzz:pos = 3'd5;
8'bz1zzzzzz:pos = 3'd6;
8'b1zzzzzzz:pos = 3'd7;
default :pos = 3'd0;
endcase
end
endmodule
Always nolatches
// synthesis verilog_input_version verilog_2001
module top_module (
input [15:0] scancode,
output reg left,
output reg down,
output reg right,
output reg up );
always @( *) begin
left = 1'b0;
down = 1'b0;
right = 1'b0;
up = 1'b0;
case (scancode)
16'he06b:left = 1'b1;
16'he072:down = 1'b1;
16'he074:right = 1'b1;
16'he075:up = 1'b1;
endcase
end
endmodule
More Verilog Features
Conditional
module top_module (
input [7:0] a, b, c, d,
output [7:0] min);//
// assign intermediate_result1 = compare? true: false;
wire [7:0] ab;
wire [7:0] cd;
assign ab = (a < b) ? a : b;
assign cd = (c < d) ? c : d;
assign min = (ab < cd) ? ab : cd;
endmodule
Reduction
module top_module (
input [7:0] in,
output parity);
assign parity = ^ in[7:0];
endmodule
Gates100
module top_module(
input [99:0] in,
output out_and,
output out_or,
output out_xor
);
assign out_and = & in[99:0];
assign out_or = | in[99:0];
assign out_xor = ^ in[99:0];
endmodule
Vector100r
module top_module(
input [99:0] in,
output [99:0] out
);
reg [99:0] out1;
always @( *) begin
for (integer i = 0;i<=99 ;i=i+1 ) begin
out1[99-i] <= in[i];
end
end
assign out = out1;
endmodule
/*
integer类型也是一种寄存器数据类型，integer类型的变量为有符号数，而reg类型的变量则为无符号数,用integer的变量都可以用reg定
义，只是用于计数更方便而已。
module top_module (
input [99:0] in,
output reg [99:0] out
);
always @(*) begin
for (int i=0;i<$bits(out);i++) // $bits() is a system function that returns the width of a signal.
out[i] = in[$bits(out)-i-1]; // $bits(out) is 100 because out is 100 bits wide.
end
endmodule
*/
Popcount255
module top_module(
input [254:0] in,
output [7:0] out );
reg [7:0] out1;
always @( *) begin
out1 = 8'b0;//赋值语句一定要放在always块里
for (integer i =0 ;i<=254 ;i=i+1 ) begin
if (in[i] == 1'b1) begin
out1 <= out1 +1'b1;
end
else
out1 <= out1;
end
end
assign out = out1;
endmodule
Adder100i
module top_module(
input [99:0] a, b,
input cin,
output [99:0] cout,
output [99:0] sum );
assign sum[0] = a[0] ^ b[0]^ cin;
assign cout[0] = a[0]&b[0] | a[0]&cin | b[0]&cin;
//这两句就可以实现一个一位全加器
genvar i;
generate
for( i=1; i<=99; i=i+1) begin:add1
assign sum[i] = a[i] ^ b[i]^ cout[i-1];
assign cout[i] = a[i]&b[i] | a[i]&cout[i-1] | b[i]&cout[i-1];
end
endgenerate
endmodule
Bcdadd100
module top_module(
input [399:0] a, b,
input cin,
output cout,
output [399:0] sum );
reg [99:0] cout_reg;
bcd_fadd (
.a(a[3:0]),
.b(b[3:0]),
.cin(cin),
.cout(cout_reg[0]),
.sum(sum[3:0])
);
genvar i;
generate
for (i = 1;i<=99 ; i=i+1) begin:fadd
bcd_fadd fadd(
.a(a[4*(i+1)-1:4*(i+1)-4]),
.b(b[4*(i+1)-1:4*(i+1)-4]),
.cin(cout_reg[i-1]),
.cout(cout_reg[i]),
.sum(sum[4*(i+1)-1:4*(i+1)-4])
);
end
endgenerate
assign cout = cout_reg[99];
endmodule
Circuits
Combinational Logic
Basic Gates
m2014 q4h
module top_module (
input in,
output out);
assign out = in ;
endmodule
m2014 q4i
module top_module (
output out);
assign out = 1'b0;
endmodule
m2014 q4e
module top_module (
input in1,
input in2,
output out);
assign out = ~(in1 | in2);
endmodule
m2014 q4f
module top_module (
input in1,
input in2,
output out);
assign out = in1 & ~in2;
endmodule
m2014 q4g
module top_module (
input in1,
input in2,
input in3,
output out);
assign out = in3 ^ ~(in1 ^ in2);
endmodule
Gates
module top_module(
input a, b,
output out_and,
output out_or,
output out_xor,
output out_nand,
output out_nor,
output out_xnor,
output out_anotb
);
assign out_and = a & b;
assign out_or = a | b;
assign out_xor = a ^ b;
assign out_nand = ~(a & b);
assign out_nor = ~(a | b);
assign out_xnor = ~(a ^ b);
assign out_anotb = a & ~b;
endmodule
7420
module top_module (
input p1a, p1b, p1c, p1d,
output p1y,
input p2a, p2b, p2c, p2d,
output p2y );
assign p1y = ~(p1a & p1b & p1c & p1d);
assign p2y = ~(p2a & p2b & p2c & p2d);
endmodule
Truthtable1
module top_module(
input x3,
input x2,
input x1, // three inputs
output f // one output
);//可以用卡诺图化简
assign f =(x3 & x1) | (~x3 & x2);
endmodule
Mt2015 eq2
module top_module ( input [1:0] A, input [1:0] B, output z );
assign z = (A == B) ? 1'b1 : 1'b0;
endmodule
Mt2015 q4a
module top_module (input x, input y, output z);
assign z = (x^y) & x;
endmodule
Mt2015 q4b
module top_module ( input x, input y, output z );
assign z = ~(x ^ y);
endmodule
Mt2015 q4
module top_module (input x, input y, output z);
wire wire1,wire2;
assign wire1 = ((x^y) & x) | (~(x ^ y));
assign wire2 = ((x^y) & x) & (~(x ^ y));
assign z = wire1 ^ wire2;
endmodule
Ringer
module top_module (
input ring,
input vibrate_mode,
output ringer, // Make sound
output motor // Vibrate
);
assign ringer = ring & ~vibrate_mode;
assign motor = ring & vibrate_mode;
endmodule
Thermostat
module top_module (
input too_cold,
input too_hot,
input mode,
input fan_on,
output heater,
output aircon,
output fan
);
assign heater = too_cold & mode;
assign aircon = too_hot & ~mode;
assign fan = fan_on | (too_cold & mode) | (too_hot & ~mode);
endmodule
Popcount3
module top_module(
input [2:0] in,
output [1:0] out );
assign out = in[0] + in[1] + in[2];
endmodule
/*
module top_module (
input [2:0] in,
output [1:0] out
);
// This is a function of 3 inputs. One method is to use a 8-entry truth table:
// in[2:0] out[1:0]
// 000 00
// 001 01
// 010 01
// 011 10
// 100 01
// 101 10
// 110 10
// 111 11
assign out[0] = (~in[2] & ~in[1] & in[0]) | (~in[2] & in[1] & ~in[0]) | (in[2] & ~in[1] & ~in[0]) | (in[2] & in[1] & in[0]);
assign out[1] = (in[1] & in[0]) | (in[2] & in[0]) | (in[2] & in[1]);
// Using the addition operator works too:
// assign out = in[0]+in[1]+in[2];
// Yet another method uses behavioural code inside a procedure (combinational always block)
// to directly implement the truth table:
always @(*) begin
case (in)
3'd0: out = 2'd0;
3'd1: out = 2'd1;
3'd2: out = 2'd1;
3'd3: out = 2'd2;
3'd4: out = 2'd1;
3'd5: out = 2'd2;
3'd6: out = 2'd2;
3'd7: out = 2'd3;
endcase
end
endmodule
*/
Gatesv
module top_module(
input [3:0] in,
output [2:0] out_both,
output [3:1] out_any,
output [3:0] out_different );
assign out_both = in[2:0] & in[3:1];
assign out_any = in[3:1] | in[2:0];
assign out_different = in[3:0] ^ {in[0],in[3:1]};
endmodule
Gatesv100
module top_module(
input [99:0] in,
output [98:0] out_both,
output [99:1] out_any,
output [99:0] out_different );
assign out_both = in[98:0] & in[99:1];
assign out_any = in[99:1] | in[98:0];
assign out_different = in[99:0] ^ {in[0],in[99:1]};
endmodule
Multiplexers
Mux2to1
module top_module(
input a, b, sel,
output out );
assign out = (sel) ? b : a;
endmodule
Mux2to1v
module top_module(
input [99:0] a, b,
input sel,
output [99:0] out );
assign out = (sel) ? b : a;
endmodule
Mux9to1v
module top_module(
input [15:0] a, b, c, d, e, f, g, h, i,
input [3:0] sel,
output reg [15:0] out );
always @( *) begin
case (sel)
4'd0:out = a;
4'd1:out = b;
4'd2:out = c;
4'd3:out = d;
4'd4:out = e;
4'd5:out = f;
4'd6:out = g;
4'd7:out = h;
4'd8:out = i;
default :
out = 16'b1111_1111_1111_1111;
endcase
end
endmodule
Mux256to1
module top_module(
input [255:0] in,
input [7:0] sel,
output reg out );
integer i;
always @( *) begin
i = sel;
out = in[i];
end
endmodule
/*
module top_module (
input [255:0] in,
input [7:0] sel,
output out
);
// Select one bit from vector in[]. The bit being selected can be variable.
assign out = in[sel];
endmodule
*/
Mux256to1v
module top_module(
input [1023:0] in,
input [7:0] sel,
output [3:0] out );
assign out = in[(4*sel)+:4];
/*
integer i;
always @( *) begin
i = sel;
out = in[(4*i)+:4];
end
big_vect[0 +:8]和big_vect [7:0]是等价的
big_vect[15 -:8]和big_vect[15:8]是等价的。
同时这里的0和15可以为变量，如果不采用这种写法，常用的[a:b]这种形式，a,b必须为常数，不能是一个变量
*/
endmodule
Arithmetic Circuits
Hadd
module top_module(
input a, b,
output cout, sum );
assign sum = a ^b;
assign cout = a & b;
endmodule
Fadd
module top_module(
input a, b, cin,
output cout, sum );
assign sum = a ^ b ^ cin;
assign cout = (a & b) | (a & cin) | (cin & b);
endmodule
Adder3
module top_module(
input [2:0] a, b,
input cin,
output [2:0] cout,
output [2:0] sum );
genvar i;
generate
for( i=0; i<=2; i=i+1) begin:add
if (i == 0) begin
assign sum[i] = a[i] ^ b[i] ^ cin;
assign cout[i] = a[i]&b[i] | a[i]&cin | b[i]&cin;
end
else
begin
assign sum[i] = a[i] ^ b[i]^ cout[i-1];
assign cout[i] = a[i]&b[i] | a[i]&cout[i-1] | b[i]&cout[i-1];
end
end
endgenerate
endmodule
m2014 q4j
module top_module (
input [3:0] x,
input [3:0] y,
output [4:0] sum);
wire [3:0] cout;
genvar i;
generate
for( i=0; i<=3; i=i+1) begin:add
if (i == 0) begin
assign sum[i] = x[i] ^ y[i];
assign cout[i] = x[i]&y[i] ;
end
else
begin
assign sum[i] = x[i] ^ y[i]^ cout[i-1];
assign cout[i] = x[i]&y[i] | x[i]&cout[i-1] | y[i]&cout[i-1];
end
end
endgenerate
assign sum[4] = cout[3];
endmodule
ece241 2014 q1c
module top_module (
input [7:0] a,
input [7:0] b,
output [7:0] s,
output overflow
); //
// assign s = ...
// assign overflow = ...
wire [7:0] cout;
genvar i;
generate
for( i=0; i<=7; i=i+1) begin:add
if (i == 0) begin
assign s[i] = a[i] ^ b[i];
assign cout[i] = a[i]&b[i] ;
end
else
begin
assign s[i] = a[i] ^ b[i]^ cout[i-1];
assign cout[i] = a[i]&b[i] | a[i]&cout[i-1] | b[i]&cout[i-1];
end
end
endgenerate
assign overflow = (cout[6] ^ cout[7]) ? 1'b1 : 1'b0;
endmodule
/*
补码加减法运算，如何判断溢出？
溢出用OF（overflow）表示：当OF=1时溢出；OF=0时，未溢出
m表示符号位是否进位（进位为1，否则为0）
n表示最高数值位是否进位（进位为1，否则为0）
*/
Adder100
module top_module(
input [99:0] a, b,
input cin,
output cout,
output [99:0] sum );
wire [99:0] cout1;
genvar i;
generate
for( i=0; i<=99; i=i+1) begin:add
if (i == 0) begin
assign sum[i] = a[i] ^ b[i] ^ cin;
assign cout1[i] = a[i]&b[i] | a[i]&cin | cin&b[i];
end
else
begin
assign sum[i] = a[i] ^ b[i]^ cout1[i-1];
assign cout1[i] = a[i]&b[i] | a[i]&cout1[i-1] | b[i]&cout1[i-1];
end
end
endgenerate
assign cout = cout1[99];
endmodule
/*看到这个我人麻了，这就是思维固化吗？
module top_module (
input [99:0] a,
input [99:0] b,
input cin,
output cout,
output [99:0] sum
);
// The concatenation {cout, sum} is a 101-bit vector.
assign {cout, sum} = a+b+cin;
endmodule
*/
Bcdadd4
module top_module(
input [15:0] a, b,
input cin,
output cout,
output [15:0] sum );
//题目说可以例化一个BCD加法器
wire [3:0] cout1;
bcd_fadd u_bcd_fadd(
.a(a[3:0]),
.b(b[3:0]),
.cin(cin),
.cout(cout1[0]),
.sum(sum[3:0])
);
genvar i;
generate
for (i = 1;i<=3 ; i=i+1) begin:bcdadd
bcd_fadd u_bcd_fadd(
.a(a[(4*i)+:4]),
.b(b[(4*i)+:4]),
.cin(cout1[i-1]),
.cout(cout1[i]),
.sum(sum[(4*i)+:4])
);
end
endgenerate
assign cout = cout1[3];
/*
//尝试自己写一个BCD加法器
wire [3:0] cout1;
assign sum[3:0] = ((a[3:0] + a[3:0] + cin) >= 10) ? (a[3:0] + b[3:0] + cin - 4'd10) : (a[3:0] + b[3:0] + cin);
assign cout1[0] = ((a[3:0] + b[3:0] + cin) >= 10) ? 1'b1 : 1'b0;
genvar i;
generate
for (i = 1;i<=3 ; i=i+1) begin:bcdadd
assign sum[(4*i)+:4] = ((a[(4*i)+:4] + b[(4*i)+:4] + cout1[i-1]) >= 10) ? (a[(4*i)+:4] + b[(4*i)+:4] + cout1[i-1] - 4'd10) : (a[(4*i)+:4] + b[(4*i)+:4] + cout1[i-1]);
assign cout1[i] = ((a[(4*i)+:4] + b[(4*i)+:4] + cout1[i-1]) >= 10) ? 1'b1 : 1'b0;
end
endgenerate
assign cout = cout1[3];
*/
endmodule
Karnaugh Map to Circuit
Kmap1
module top_module(
input a,
input b,
input c,
output out );
assign out = a&~b | ~b&c | b;
endmodule
Kmap2
module top_module(
input a,
input b,
input c,
input d,
output out );
assign out = ~a&~d | a&~b&~c | ~b&~c&d | a&c&d | ~a&b&c;
endmodule
Kmap3
module top_module(
input a,
input b,
input c,
input d,
output out );
assign out = a | ~a&~b&c;
endmodule
Kmap4
module top_module(
input a,
input b,
input c,
input d,
output out );
assign out = ~a&b&~c&~d | a&~b&~c&~d | ~a&~b&~c&d | a&b&~c&d | ~a&b&c&d | a&~b&c&d | ~a&~b&c&~d | a&b&c&~d ;
endmodule
ece241 2013 q2
module top_module (
input a,
input b,
input c,
input d,
output out_sop,
output out_pos
);
//最小项的反是最大项，最大项的反是最小项。最常用的是最小项。
assign out_sop = c&d | ~a&~b&c;
assign out_pos = ~((~c|~d) & (a|b|~c));
endmodule
m2014 q3
module top_module (
input [4:1] x,
output f );
assign f = ~x[1]&x[3] | x[1]&x[2]&x[4];
endmodule
2012 q1g
module top_module (
input [4:1] x,
output f
);
assign f = ~x[2]&~x[3]&~x[4] | ~x[1]&x[3] | x[1]&x[2]&x[3]&x[4] | x[1]&~x[2]&x[3]&~x[4];
endmodule
ece241 2014 q3
module top_module (
input c,
input d,
output [3:0] mux_in
);
assign mux_in[0] = ~c&d | c&d | c&~d;
assign mux_in[1] = 1'b0;
assign mux_in[3] = c&d;
assign mux_in[2] = ~c&~d | c&~d;
endmodule
Sequential Logic
Latches and Flip-Flops
Dff
module top_module (
input clk, // Clocks are used in sequential circuits
input d,
output reg q );//
// Use a clocked always block
// copy d to q at every positive edge of clk
// Clocked always blocks should use non-blocking assignments
always @(posedge clk) begin
q <= d;
end
endmodule
Dff8
module top_module (
input clk,
input [7:0] d,
output reg [7:0] q
);
always @(posedge clk) begin
q <= d;
end
endmodule
Dff8r
module top_module (
input clk,
input reset, // Synchronous reset
input [7:0] d,
output reg [7:0] q
);
always @(posedge clk ) begin
if (reset) begin
q <= 8'b0;
end
else
q <= d;
end
endmodule
Dff8p
module top_module (
input clk,
input reset,
input [7:0] d,
output reg [7:0] q
);
always @(negedge clk) begin
if (reset) begin
q <= 8'h34;
end
else
q <= d;
end
endmodule
Dff8ar
module top_module (
input clk,
input areset, // active high asynchronous reset
input [7:0] d,
output reg [7:0] q
);
always @(posedge clk or posedge areset) begin
if (areset) begin
q <= 8'b0;
end
else
q <= d;
end
endmodule
Dff16e
module top_module (
input clk,
input resetn,
input [1:0] byteena,
input [15:0] d,
output reg [15:0] q
);
always @(posedge clk) begin
if (!resetn) begin
q <= 16'b0;
end
else
begin
case (byteena)
2'b00:
q <= q;
2'b01:
q <= {q[15:8],d[7:0]};
2'b10:
q <= {d[15:8],q[7:0]};
2'b11:
q <= d;
endcase
end
end
endmodule
m2014 q4a
module top_module (
input d,
input ena,
output reg q);
always @( *) begin
if (ena) begin
q <= d;
end
else
q <= q;
end
endmodule
m2014 q4b
module top_module (
input clk,
input d,
input ar, // asynchronous reset
output reg q);
always @(posedge clk or posedge ar) begin
if (ar) begin
q <= 1'b0;
end
else
q <= d;
end
endmodule
m2014 q4c
module top_module (
input clk,
input d,
input r, // synchronous reset
output reg q);
always @(posedge clk) begin
if (r) begin
q <= 1'b0;
end
else
q <= d;
end
endmodule
m2014 q4d
module top_module (
input clk,
input in,
output reg out);
wire d;
assign d = in ^ out;
always @(posedge clk) begin
out <= d;
end
endmodule
Mt2015 muxdff
module top_module (
input clk,
input L,
input r_in,
input q_in,
output reg Q);
always @(posedge clk) begin
if (L) begin
Q <= r_in;
end
else
Q <= q_in;
end
endmodule
2014 q4a
module top_module (
input clk,
input w, R, E, L,
output reg Q
);
always @(posedge clk) begin
if (L) begin
Q <= R;
end
else
begin
if (E) begin
Q <= w;
end
else
Q <= Q;
end
end
endmodule
ece241 2014 q4
module top_module (
input clk,
input x,
output z
);
reg [2:0] Q;
always @(posedge clk) begin
Q[0] <= x ^ Q[0];
Q[1] <= x & ~Q[1];
Q[2] <= x | ~Q[2];
end
assign z = ~| Q;
endmodule
ece241 2013 q7
module top_module (
input clk,
input j,
input k,
output reg Q);
always @(posedge clk) begin
if (j) begin
if (k) begin
Q <= ~Q;
end
else
Q <= 1'b1;
end
else
begin
if (k) begin
Q <= 1'b0;
end
else
Q <= Q;
end
end
endmodule
Edgedetect
module top_module (
input clk,
input [7:0] in,
output reg [7:0] pedge
);
reg [7:0] in1;
always @(posedge clk) begin
in1 <= in;
end
always @(posedge clk) begin
for (integer i = 0;i<=7 ;i = i+1 ) begin
if ((in[i] == 1'b1) && (in1[i] == 1'b0)) begin
pedge[i] <= 1'b1;
end
else
pedge[i] <= 1'b0;
end
end
endmodule
/*
module top_module(
input clk,
input [7:0] in,
output reg [7:0] pedge);
reg [7:0] d_last;
always @(posedge clk) begin
d_last <= in; // Remember the state of the previous cycle
pedge <= in & ~d_last; // A positive edge occurred if input was 0 and is now 1.
end
endmodule
*/
Edgedetect2
module top_module (
input clk,
input [7:0] in,
output reg [7:0] anyedge
);
reg [7:0] last_in;
always @(posedge clk) begin
last_in <= in;
end
always @(posedge clk) begin
anyedge <= in ^ last_in;
end
endmodule
Edgecapture
module top_module (
input clk,
input reset,
input [31:0] in,
output reg [31:0] out
);
reg [31:0] in1;
always @(posedge clk) begin
in1 <= in;
end
always @(posedge clk) begin
if (reset) begin
out <= 32'b0;
end
else
out <= ~in & in1 | out;//可以利用或运算来保持out输出1之后一直保持不变，同样的道理如果想保持输出的0不变可以使用and
end
endmodule
/*
reg [31:0] in1;
wire [31:0] out1;
always @(posedge clk) begin
in1 <= in;
end
assign out1 = ~in & in1;
always @(posedge clk) begin
if (reset) begin
out <= 32'b0;
end
else
begin
for ( integer i=0 ;i<=31 ;i=i+1 ) begin
if (out1[i]) begin
out[i] <= 1'b1;
end
end
end
end
*/
Dualedge
module top_module (
input clk,
input d,
output q
);
reg q_d1;
reg q_d2;
always@(posedge clk)begin
q_d1 <= d ^ q_d2;
end
always@(negedge clk)begin
q_d2 <= d ^ q_d1;
end
assign q = q_d1 ^ q_d2;
//上升沿和下降沿交替触发，使两个寄存器交替变化，最后用异或来输出q,这个题目感觉有难度。
//原文链接：https://blog.csdn.net/wangkai_2019/article/details/106238994
endmodule
Counters
Count15
module top_module (
input clk,
input reset, // Synchronous active-high reset
output reg [3:0] q);
always @(posedge clk) begin
if (reset) begin
q <= 4'b0;
end
else if (q == 4'd15) begin
q <= 4'b0;
end
else
q <= q + 1'b1;
end
endmodule
/*
module top_module(
input clk,
input reset,
output reg [3:0] q);
always @(posedge clk)
if (reset)
q <= 0;
else
q <= q+1; // Because q is 4 bits, it rolls over from 15 -> 0.
// If you want a counter that counts a range different from 0 to (2^n)-1,
// then you need to add another rule to reset q to 0 when roll-over should occur.
endmodule
*/
Count10
module top_module (
input clk,
input reset, // Synchronous active-high reset
output reg [3:0] q);
always @(posedge clk) begin
if (reset) begin
q <= 4'b0;
end
else if(q == 4'd9) begin
q <= 4'b0;
end
else
q <= q +1'b1;
end
endmodule
Count1to10
module top_module (
input clk,
input reset,
output reg [3:0] q);
always @(posedge clk) begin
if (reset) begin
q <= 4'b1;
end
else if(q == 4'd10) begin
q <= 4'b1;
end
else
q <= q + 1'b1;
end
endmodule
Countslow
module top_module (
input clk,
input slowena,
input reset,
output reg [3:0] q);
always @(posedge clk) begin
if (reset) begin
q <= 4'b0;
end
else if(slowena) begin
q <= q + 1'b1;
if(q == 4'd9) begin
q <= 4'b0;
end
end
else
q <= q;
end
endmodule
ece241 2014 q7a
module top_module (
input clk,
input reset,
input enable,
output [3:0] Q,
output c_enable,
output c_load,
output [3:0] c_d
); //
wire load1;
assign load1 = (((Q == 4'd12)&enable) || (reset) ) ? 1'b1 : 1'b0;
//一定要注意，是在计数到12，并且使能状态之下才可以重装载
count4 the_counter (
.clk(clk),
.enable(enable),
.load(load1),
.d(4'b1),
.Q(Q)
);
assign c_enable = enable;
assign c_load = load1;
assign c_d = 4'b1;
endmodule
ece241 2014 q7b
module top_module (
input clk,
input reset,
output reg OneHertz,
output reg [2:0] c_enable
); //
reg [3:0] q0,q1,q2;
always @( *) begin
c_enable[0] <= 1'b1;
end
always @(posedge clk) begin
if (q0 == 4'd8) begin
c_enable[1] <= 1'b1;
end
else
c_enable[1] <= 1'b0;
end
always @(posedge clk) begin
if ((q1 == 4'd9) && (q0 == 4'd8)) begin
c_enable[2] <= 1'b1;
end
else
c_enable[2] <= 1'b0;
end
bcdcount count1(
.clk(clk),
.reset(reset),
.enable(c_enable[0]),
.Q(q0)
);
bcdcount count2(
.clk(clk),
.reset(reset),
.enable(c_enable[1]),
.Q(q1)
);
bcdcount count3(
.clk(clk),
.reset(reset),
.enable(c_enable[2]),
.Q(q2)
);
always @(posedge clk) begin
if ((q2 == 4'd9) && (q1 == 4'd9) && (q0 == 4'd8)) begin
OneHertz <= 1'b1;
end
else
OneHertz <= 1'b0;
end
//用always就会延迟一个时钟，所以要到998，如果用assign的话就不会延时，所以可以写到999
//因为要求每个计数器的时钟都是同一时钟，所以使能位就担任起不同时钟的作用了
endmodule
Countbcd
module top_module (
input clk,
input reset, // Synchronous active-high reset
output [3:1] ena,
output reg [15:0] q);
wire [3:0] ena1;
assign ena1[0] = 1'b1;
always @(posedge clk) begin
if (reset) begin
q[3:0] <= 4'b0;
end
else if (ena1[0]) begin
if(q[3:0] == 4'd9) begin
q[3:0] <= 4'b0;
end
else
q[3:0] <= q[3:0] +1'b1;
end
end
assign ena1[1] = (q[3:0] == 4'd9) ? 1'b1 : 1'b0;
always @(posedge clk) begin
if (reset) begin
q[7:4] <= 4'b0;
end
else if (ena1[1]) begin
if(q[7:4] == 4'd9) begin
q[7:4] <= 4'b0;
end
else
q[7:4] <= q[7:4] +1'b1;
end
end
assign ena1[2] = ((q[3:0] == 4'd9) && (q[7:4] == 4'd9)) ? 1'b1 : 1'b0;
always @(posedge clk) begin
if (reset) begin
q[11:8] <= 4'b0;
end
else if (ena1[2]) begin
if(q[11:8] == 4'd9) begin
q[11:8] <= 4'b0;
end
else
q[11:8] <= q[11:8] +1'b1;
end
end
assign ena1[3] = ((q[3:0] == 4'd9) && (q[7:4] == 4'd9) && (q[11:8] == 4'd9)) ? 1'b1 : 1'b0;
always @(posedge clk) begin
if (reset) begin
q[15:12] <= 4'b0;
end
else if (ena1[3]) begin
if(q[15:12] == 4'd9) begin
q[15:12] <= 4'b0;
end
else
q[15:12] <= q[15:12] +1'b1;
end
end
assign ena = ena1[3:1];
//
endmodule
Count clock
module top_module(
input clk,
input reset,
input ena,
output reg pm,
output [7:0] hh,
output [7:0] mm,
output [7:0] ss);
wire ss_en,ss_60_en; //秒个位进十位的进位脉冲，秒记满59的时候产生进位分钟的脉冲
reg [3:0] ss_one,ss_ten; //秒的个位和十位 ，以下类推
wire mm_en,mm_60_en;
reg [3:0] mm_one,mm_ten;
wire hh_en,pm_en; //产生AM PM交换时产生的脉冲，到11点59分59秒的时候产生一个脉冲，使pm取反
reg [3:0] hh_one,hh_ten;
assign ss = {ss_ten,ss_one};
assign mm = {mm_ten,mm_one};
assign hh = {hh_ten,hh_one};
always @(posedge clk) begin
if (reset) begin
ss_one <= 4'b0;
end
else if(ena) begin
if (ss_one == 4'd9) begin
ss_one <= 4'b0;
end
else
ss_one <= ss_one + 1'b1;
end
end
assign ss_en = ((ss_one == 4'd9) && ena) ? 1'b1 : 1'b0;
always @(posedge clk) begin
if (reset) begin
ss_ten <= 4'b0;
end
else if(ss_en) begin
if ((ss_one == 4'd9) && (ss_ten == 4'd5) && ena) begin
ss_ten <= 4'b0;
end
else
ss_ten <= ss_ten + 1'b1;
end
end
assign ss_60_en = ((ss_one == 4'd9) && (ss_ten == 4'd5) && ena) ? 1'b1 : 1'b0;
always @(posedge clk) begin
if (reset) begin
mm_one <= 4'b0;
end
else if(ss_60_en) begin
if (mm_one == 4'd9) begin
mm_one <= 4'b0;
end
else
mm_one <= mm_one + 1'b1;
end
end
assign mm_en = ((mm_one == 4'd9) && (ss_one == 4'd9) && (ss_ten == 4'd5) && ena) ? 1'b1 : 1'b0;
always @(posedge clk) begin
if (reset) begin
mm_ten <= 4'b0;
end
else if(mm_en) begin
if ((mm_one == 4'd9) && (mm_ten == 4'd5) && ena && (ss_one == 4'd9) && (ss_ten == 4'd5)) begin
mm_ten <= 4'b0;
end
else
mm_ten <= mm_ten + 1'b1;
end
end
assign mm_60_en = ((mm_one == 4'd9) && (mm_ten == 4'd5) && ena && (ss_one == 4'd9) && (ss_ten == 4'd5)) ? 1'b1 : 1'b0;
always @(posedge clk) begin
if (reset) begin
hh_one <= 4'd2;
end
else if(mm_60_en) begin
if ((hh_one == 4'd2) && (hh_ten == 4'd1) && (mm_one == 4'd9) && (mm_ten == 4'd5) && ena && (ss_one == 4'd9) && (ss_ten == 4'd5)) begin
hh_one <= 4'd1;
end
else if ((hh_one == 4'd9) && (hh_ten == 4'd0) && (mm_one == 4'd9) && (mm_ten == 4'd5) && ena && (ss_one == 4'd9) && (ss_ten == 4'd5)) begin
hh_one <= 4'd0;
end
else
hh_one <= hh_one + 1'b1;
end
end
assign hh_en = ((hh_one == 4'd9) && (hh_ten == 4'd0) && (mm_one == 4'd9) && (mm_ten == 4'd5) && ena && (ss_one == 4'd9) && (ss_ten == 4'd5)) ? 1'b1 : 1'b0;
always @(posedge clk) begin
if (reset) begin
hh_ten <= 4'b1;
end
else if ((hh_one == 4'd2) && (hh_ten == 4'd1) && (mm_one == 4'd9) && (mm_ten == 4'd5) && ena && (ss_one == 4'd9) && (ss_ten == 4'd5)) begin
hh_ten <= 4'd0;
end
else if(hh_en) begin
hh_ten <= 4'd1;
end
end
assign pm_en = ((hh_one == 4'd1) && (hh_ten == 4'd1) && (mm_one == 4'd9) && (mm_ten == 4'd5)&& (ss_one == 4'd9) && (ss_ten == 4'd5) && ena) ? 1'b1 : 1'b0;
always @(posedge clk) begin
if (reset) begin
pm <= 1'b0;
end
else if (pm_en) begin
pm <= ~pm;
end
end
//注意在产生进位脉冲的时候，要考虑到最小单位的进位，比如在判断分钟的进位时，要等到秒计数到59的时候才产生进位脉冲
endmodule
Shift Registers
Shift4
module top_module(
input clk,
input areset, // async active-high reset to zero
input load,
input ena,
input [3:0] data,
output reg [3:0] q);
always @(posedge clk or posedge areset) begin
if (areset) begin
q <= 4'b0;
end
else if (load) begin
q <= data;
end
else if (ena) begin
q <= {1'b0,q[3:1]};
end
end
endmodule
Rotate100
module top_module(
input clk,
input load,
input [1:0] ena,
input [99:0] data,
output reg [99:0] q);
always @(posedge clk) begin
if (load) begin
q <= data;
end
else
begin
case (ena)
2'b01:q <= {q[0],q[99:1]};
2'b10:q <= {q[98:0],q[99]};
default :
q <= q;
endcase
end
end
endmodule
Shift18
module top_module(
input clk,
input load,
input ena,
input [1:0] amount,
input [63:0] data,
output reg [63:0] q);
always @(posedge clk) begin
if (load) begin
q <= data;
end
else if(ena) begin
case (amount)
2'b00:q <= {q[62:0],1'b0};
2'b01:q <= {q[55:0],8'b0};
2'b10:q <= {q[63],q[63:1]};
2'b11:q <= {{8{q[63]}},q[63:8]};
endcase
end
else
q <= q;
end
endmodule
Lfsr5
module top_module(
input clk,
input reset, // Active-high synchronous reset to 5'h1
output reg [4:0] q
);
always @(posedge clk) begin
if (reset) begin
q <= 5'h1;
end
else
begin
q[4] <= 0 ^ q[0];
q[3] <= q[4];
q[2] <= q[3] ^ q[0];
q[1] <= q[2];
q[0] <= q[1];
end
end
endmodule
/*
线性反馈移位寄存器（英语：Linear feedback shift register，LFSR)
module top_module(
input clk,
input reset,
output reg [4:0] q);
reg [4:0] q_next; // q_next is not a register
Convenience: Create a combinational block of logic that computes
what the next value should be. For shorter code, I first shift
all of the values and then override the two bit positions that have taps.
A logic synthesizer creates a circuit that behaves as if the code were
executed sequentially, so later assignments override earlier ones.
Combinational always block: Use blocking assignments.
逻辑合成器创建的电路就像代码一样顺序执行，所以后面的赋值会覆盖前面的赋值。
always @(*) begin
q_next = q[4:1]; // Shift all the bits. This is incorrect for q_next[4] and q_next[2]，左边5位，右边4位，则会赋值给4个低位，高位为0
q_next[4] = q[0]; // Give q_next[4] and q_next[2] their correct assignments
q_next[2] = q[3] ^ q[0];
end
在 assign 赋值操作中，如果等号左右两侧信号的位宽不同，那么就会进行截断或者补零操作。
左侧信号位宽大于右侧信号位宽，右值的低位赋予左值对应的低位，左值高位的部分赋零。
左侧信号位宽小于右侧信号位宽，右值的低位赋予左值对应的低位，右值高位的部分直接被截断。即保留右值的低位。
This is just a set of DFFs. I chose to compute the connections between the
DFFs above in its own combinational always block, but you can combine them if you wish.
You'll get the same circuit either way.
Edge-triggered always block: Use non-blocking assignments.
always @(posedge clk) begin
if (reset)
q <= 5'h1;
else
q <= q_next;
end
endmodule
*/
Mt2015 lfsr
module top_module (
input [2:0] SW, // R
input [1:0] KEY, // L and clk
output [2:0] LEDR); // Q
reg [2:0] Q;
wire [2:0] R;
assign LEDR = Q;
assign R = SW;
always @(posedge KEY[0]) begin
if (KEY[1]) begin
Q[0] <= R[0];
Q[1] <= R[1];
Q[2] <= R[2];
end
else
begin
Q[0] <= Q[2];
Q[1] <= Q[0];
Q[2] <= Q[2] ^ Q[1];
end
end
endmodule
Lfsr32
module top_module(
input clk,
input reset, // Active-high synchronous reset to 32'h1
output reg [31:0] q
);
reg [31:0] q_next;
always @(*) begin
q_next = q[31:1];
q_next[31] = q[0];//这是32抽头，和0异或
q_next[0] = q[0] ^ q[1];
q_next[1] = q[0] ^ q[2];
q_next[21] = q[0] ^ q[22];
end
always @(posedge clk) begin
if (reset) begin
q <= 32'h1;
end
else
q <= q_next;
end
endmodule
m2014 q4k
module top_module (
input clk,
input resetn, // synchronous reset
input in,
output out);
reg [3:0] Q;
always @(posedge clk) begin
if (!resetn) begin
Q <= 4'b0;
end
else
begin
Q[0] <= in;
Q[1] <= Q[0];
Q[2] <= Q[1];
Q[3] <= Q[2];
end
end
assign out = Q[3];
endmodule
/*
module top_module (
input clk,
input resetn,
input in,
output out
);
reg [3:0] sr;
// Create a shift register named sr. It shifts in "in".
always @(posedge clk) begin
if (~resetn) // Synchronous active-low reset
sr <= 0;
else
sr <= {sr[2:0], in};
end
assign out = sr[3]; // Output the final bit (sr[3])
endmodule
*/
2014 q4b
module top_module (
input [3:0] SW,
input [3:0] KEY,
output [3:0] LEDR
); //
wire [3:0] R;
wire clk,E,L,W;
reg [3:0] Q;
assign R = SW;
assign clk = KEY[0];
assign E = KEY[1];
assign L = KEY[2];
assign W = KEY[3];
assign LEDR = Q;
MUXDFF MUXDFF_1(
.clk(clk),
.w(W),
.R(R[3]),
.E(E),
.L(L),
.Q(Q[3])
);
MUXDFF MUXDFF_2(
.clk(clk),
.w(Q[3]),
.R(R[2]),
.E(E),
.L(L),
.Q(Q[2])
);
MUXDFF MUXDFF_3(
.clk(clk),
.w(Q[2]),
.R(R[1]),
.E(E),
.L(L),
.Q(Q[1])
);
MUXDFF MUXDFF_4(
.clk(clk),
.w(Q[1]),
.R(R[0]),
.E(E),
.L(L),
.Q(Q[0])
);
endmodule
module MUXDFF (
input clk,
input w, R, E, L,
output reg Q
);
always @(posedge clk) begin
if (L) begin
Q <= R;
end
else
begin
if (E) begin
Q <= w;
end
else
Q <= Q;
end
end
endmodule
ece241 2013 q12
module top_module (
input clk,
input enable,
input S,
input A, B, C,
output reg Z );
reg [7:0] Q;
wire[2:0] chose;
assign chose = {A,B,C};
always @(posedge clk) begin
if (enable) begin
Q <= {Q[6:0],S};
end
end
always @(*) begin
case (chose)
3'd0: Z = Q[0];
3'd1: Z = Q[1];
3'd2: Z = Q[2];
3'd3: Z = Q[3];
3'd4: Z = Q[4];
3'd5: Z = Q[5];
3'd6: Z = Q[6];
3'd7: Z = Q[7];
default :
Z = 1'b0;
endcase
end
endmodule
/*
module top_module (
input clk,
input enable,
input S,
input A, B, C,
output reg Z
);
reg [7:0] q;
// The final circuit is a shift register attached to a 8-to-1 mux.
// Create a 8-to-1 mux that chooses one of the bits of q based on the three-bit number {A,B,C}:
// There are many other ways you could write a 8-to-1 mux
// (e.g., combinational always block -> case statement with 8 cases).
assign Z = q[ {A, B, C} ];//妙哉
// Edge-triggered always block: This is a standard shift register (named q) with enable.
// When enabled, shift to the left by 1 (discarding q[7] and and shifting in S).
always @(posedge clk) begin
if (enable)
q <= {q[6:0], S};
end
endmodule
*/
More Circuits
Rule90
module top_module(
input clk,
input load,
input [511:0] data,
output reg [511:0] q );
wire [511:0] q_l,q_r,q_next;
assign q_l = {q[510:0],1'b0};
assign q_r = {1'b0,q[511:1]};
assign q_next = q_l ^ q_r;
always @(posedge clk) begin
if (load) begin
q <= data;
end
else
q <= q_next;
end
endmodule
Rule110
module top_module(
input clk,
input load,
input [511:0] data,
output reg [511:0] q
);
wire [511:0] q_l,q_r,q_next;
assign q_r = {q[510:0],1'b0};
assign q_l = {1'b0,q[511:1]};
assign q_next = ~q_l & q | ~q_l & ~q & q_r | q_l & q & ~q_r | q_l & ~q & q_r;
always @(posedge clk) begin
if (load) begin
q <= data;
end
else
q <= q_next;
end
endmodule
Conwaylife
John Conway, mathematician and creator of the Game of Life cellular automaton, passed away from COVID-19 on April 11, 2020.
module top_module(
input clk,
input load,
input [255:0] data,
output reg [255:0] q );
//做之前应该画画图，看着图做。
reg [2:0] sum;
reg [255:0] q_next;
always @( *) begin
for (integer i= 0;i<=255 ; i = i+1) begin
if (i == 0) begin
sum = q[1]+q[16]+q[15]+q[240]+q[241]+q[31]+q[17]+q[255];
end
else if (i == 15) begin
sum = q[14]+q[255]+q[0]+q[31]+q[254]+q[240]+q[16]+q[30];
end
else if (i == 240) begin
sum = q[224]+q[241]+q[0]+q[255]+q[225]+q[239]+q[1]+q[15];
end
else if (i == 255) begin
sum = q[254]+q[239]+q[240]+q[15]+q[238]+q[224]+q[14]+q[0];
end
else if (i%16 == 0) begin
sum = q[i+1]+q[i+15]+q[i+16]+q[i+17]+q[i+31]+q[i-16]+q[i-15]+q[i-1];
end
else if (i%16 == 15) begin
sum = q[i-1]+q[i-15]+q[i+16]+q[i+15]+q[i+1]+q[i-16]+q[i-17]+q[i-31];
end
else if ((i>=241) && (i<=254)) begin
sum = q[i-1]+q[i+1]+q[i-16]+q[i-17]+q[i-15]+q[i-240]+q[i-241]+q[i-239];
end
else if ((i>=1) && (i<=14)) begin
sum = q[i-1]+q[i+1]+q[i+16]+q[i+15]+q[i+17]+q[i+240]+q[i+241]+q[i+239];
end
else
sum = q[i-1]+q[i+1]+q[i-16]+q[i-15]+q[i-17]+q[i+16]+q[i+15]+q[i+17];
case (sum)
3'd0:q_next[i] = 1'b0;
3'd1:q_next[i] = 1'b0;
3'd2:q_next[i] = q[i];
3'd3:q_next[i] = 1'b1;
default:
q_next[i] = 1'b0;
endcase
end
end
always @(posedge clk) begin
if (load) begin
q <= data;
end
else
q <= q_next;
end
endmodule
Finite State Machines
Fsm1
module top_module(
input clk,
input areset, // Asynchronous reset to state B
input in,
output out);//
parameter A=0, B=1;
reg state, next_state;
always @(*) begin // This is a combinational always block
// State transition logic
case (state)
A:
begin
if (in == 1'b0) begin
next_state = B;
end
else
next_state = A;
end
B:
begin
if (in == 1'b0) begin
next_state = A;
end
else
next_state = B;
end
endcase
end
always @(posedge clk, posedge areset) begin // This is a sequential always block
// State flip-flops with asynchronous reset
if (areset) begin
state <= B;
end
else
state <= next_state;
end
// Output logic
// assign out = (state == ...);
assign out = (state == B) ? 1'b1 : 1'b0;
endmodule
/*
module top_module (
input clk,
input in,
input areset,
output out
);
// Give state names and assignments. I'm lazy, so I like to use decimal numbers.
// It doesn't really matter what assignment is used, as long as they're unique.
parameter A=0, B=1;
reg state; // Ensure state and next are big enough to hold the state encoding.
reg next;
// A finite state machine is usually coded in three parts:
// State transition logic
// State flip-flops
// Output logic
// It is sometimes possible to combine one or more of these blobs of code
// together, but be careful: Some blobs are combinational circuits, while some
// are clocked (DFFs).
// Combinational always block for state transition logic. Given the current state and inputs,
// what should be next state be?
// Combinational always block: Use blocking assignments.
always@(*) begin
case (state)
A: next = in ? A : B;
B: next = in ? B : A;
endcase
end
// Edge-triggered always block (DFFs) for state flip-flops. Asynchronous reset.
always @(posedge clk, posedge areset) begin
if (areset) state <= B; // Reset to state B
else state <= next; // Otherwise, cause the state to transition
end
// Combinational output logic. In this problem, an assign statement is the simplest.
// In more complex circuits, a combinational always block may be more suitable.
assign out = (state==B);
endmodule
*/
Fsm1s
// Note the Verilog-1995 module declaration syntax here:
module top_module(clk, reset, in, out);
input clk;
input reset; // Synchronous reset to state B
input in;
output out;
parameter A=0, B=1;
reg state, next_state;
always @(*) begin // This is a combinational always block
// State transition logic
case (state)
A:
begin
if (in == 1'b0) begin
next_state = B;
end
else
next_state = A;
end
B:
begin
if (in == 1'b0) begin
next_state = A;
end
else
next_state = B;
end
endcase
end
always @(posedge clk) begin // This is a sequential always block
// State flip-flops with asynchronous reset
if (reset) begin
state <= B;
end
else
state <= next_state;
end
// Output logic
// assign out = (state == ...);
assign out = (state == B) ? 1'b1 : 1'b0;
endmodule
/*
// Note the Verilog-1995 module declaration syntax here:
module top_module(clk, reset, in, out);
input clk;
input reset; // Synchronous reset to state B
input in;
output out;//
reg out;
// Fill in state name declarations
reg present_state, next_state;
always @(posedge clk) begin
if (reset) begin
// Fill in reset logic
end else begin
case (present_state)
// Fill in state transition logic
endcase
// State flip-flops
present_state = next_state;
case (present_state)
// Fill in output logic
endcase
end
end
endmodule
*/
Fsm2
module top_module(
input clk,
input areset, // Asynchronous reset to OFF
input j,
input k,
output out); //
parameter OFF=0, ON=1;
reg state, next_state;
always @(*) begin
// State transition logic
case (state)
OFF:
begin
if (j == 1'b1) begin
next_state = ON;
end
else
next_state = state;
end
ON:
begin
if (k == 1'b1) begin
next_state = OFF;
end
else
next_state = state;
end
endcase
end
always @(posedge clk, posedge areset) begin
// State flip-flops with asynchronous reset
if (areset) begin
state <= OFF;
end
else
state <= next_state;
end
// Output logic
// assign out = (state == ...);
assign out = (state == ON);
endmodule
Fsm2s
module top_module(
input clk,
input reset, // Asynchronous reset to OFF
input j,
input k,
output out); //
parameter OFF=0, ON=1;
reg state, next_state;
always @(*) begin
// State transition logic
case (state)
OFF:
begin
if (j == 1'b1) begin
next_state = ON;
end
else
next_state = state;
end
ON:
begin
if (k == 1'b1) begin
next_state = OFF;
end
else
next_state = state;
end
endcase
end
always @(posedge clk) begin
// State flip-flops with asynchronous reset
if (reset) begin
state <= OFF;
end
else
state <= next_state;
end
// Output logic
// assign out = (state == ...);
assign out = (state == ON);
endmodule
Fsm3comb
module top_module(
input in,
input [1:0] state,
output reg [1:0] next_state,
output out); //
parameter A=0, B=1, C=2, D=3;
// State transition logic: next_state = f(state, in)
always @( *) begin
case (state)
A:
begin
case (in)
1'b0:next_state = A;
1'b1:next_state = B;
endcase
end
B:
begin
case (in)
1'b0:next_state = C;
1'b1:next_state = B;
endcase
end
C:
begin
case (in)
1'b0:next_state = A;
1'b1:next_state = D;
endcase
end
D:
begin
case (in)
1'b0:next_state = C;
1'b1:next_state = B;
endcase
end
endcase
end
assign out = (state == D);
// Output logic: out = f(state) for a Moore state machine
endmodule
Fsm3onehot
module top_module(
input in,
input [3:0] state,
output [3:0] next_state,
output out); //
parameter A=0, B=1, C=2, D=3;
// State transition logic: Derive an equation for each state flip-flop.
assign next_state[A] = ~in & (state[A] | state[C]);
assign next_state[B] = in & (state[A] | state[B]| state[D]);
assign next_state[C] = ~in & (state[B] | state[D]);
assign next_state[D] = in & state[C];
// Output logic:
assign out = state[D];
/*本题的关键是理解题目的意思，题目的输入和输出的状态信息都是独热码，需要用逻辑电路的方式来判断下一个状态
独热码可以理解为已经将二进制编码进行译码之后的结果，就像是经过了3-8译码器一样，因此使用独热码可以节约逻辑资源，
但是，独热码会浪费更多的寄存器，因此状态比较少的时候可以使用独热码来节约逻辑资源，提升运行速度*/
endmodule
Fsm3
module top_module(
input clk,
input in,
input areset,
output out); //
reg [4:0] state,next_state;
parameter A=4'b0001,B=4'b0010,C=4'b0100,D=4'b1000;
// State transition logic
always @( *) begin
case (state)
A:next_state = in ? B : A;
B:next_state = in ? B : C;
C:next_state = in ? D : A;
D:next_state = in ? B : C;
/*我的太不简洁了
A:
begin
if (in) begin
next_state = B;
end
else
next_state = A;
end
B:
begin
if (in) begin
next_state = B;
end
else
next_state = C;
end
C:
begin
if (in) begin
next_state = D;
end
else
next_state = A;
end
D:
begin
if (in) begin
next_state = B;
end
else
next_state = C;
end
*/
default : next_state = A;
endcase
end
// State flip-flops with asynchronous reset
always @(posedge clk or posedge areset) begin
if (areset) begin
state <= A;
end
else
state <= next_state;
end
// Output logic
assign out = (state == D) ;
endmodule
/*
module top_module (
input clk,
input in,
input areset,
output out
);
// Give state names and assignments. I'm lazy, so I like to use decimal numbers.
// It doesn't really matter what assignment is used, as long as they're unique.
parameter A=0, B=1, C=2, D=3;
reg [1:0] state; // Make sure state and next are big enough to hold the state encodings.
reg [1:0] next;
// Combinational always block for state transition logic. Given the current state and inputs,
// what should be next state be?
// Combinational always block: Use blocking assignments.
always@(*) begin
case (state)
A: next = in ? B : A;
B: next = in ? B : C;
C: next = in ? D : A;
D: next = in ? B : C;
endcase
end
// Edge-triggered always block (DFFs) for state flip-flops. Asynchronous reset.
always @(posedge clk, posedge areset) begin
if (areset) state <= A;
else state <= next;
end
// Combinational output logic. In this problem, an assign statement is the simplest.
assign out = (state==D);
endmodule
*/
Fsm3s
module top_module(
input clk,
input in,
input reset,
output out); //
reg [4:0] state,next_state;
parameter A=4'b0001,B=4'b0010,C=4'b0100,D=4'b1000;
// State transition logic
always @( *) begin
case (state)
A:next_state = in ? B : A;
B:next_state = in ? B : C;
C:next_state = in ? D : A;
D:next_state = in ? B : C;
default : next_state = A;
endcase
end
// State flip-flops with asynchronous reset
always @(posedge clk) begin
if (reset) begin
state <= A;
end
else
state <= next_state;
end
// Output logic
assign out = (state == D) ;
endmodule
ece241 2013 q4
module top_module (
input clk,
input reset,
input [3:1] s,
output fr3,
output fr2,
output fr1,
output dfr
);
reg [3:0] out;
assign {fr3,fr2,fr1,dfr} = out;
reg [2:0] state,next_state,last_state;
parameter A=3'd1,B=3'd2,C=3'd3,D=3'd4;
always @( *) begin
case (state)
A:
begin
next_state = (s == 3'b011) ? B : A;
if (s == 3'b011) begin
end
end
B:
begin
if (s == 3'b001) begin
next_state = C;
end
else if (s == 3'b111) begin
next_state = A;
end
else
next_state = B;
end
C:
begin
if (s == 3'b000) begin
next_state = D;
end
else if (s == 3'b011) begin
next_state = B;
end
else
next_state = C;
end
D:
begin
next_state = (s == 3'b001) ? C : D;
if (s == 3'b001) begin
end
end
endcase
end
always @(posedge clk) begin
if (reset) begin
state <= D;
end
else
state <= next_state;
end
always @(*) begin
case (state)
A:
begin
out[3:1] = 3'b000;
end
B:
begin
out[3:1] = 3'b001;
end
C:
begin
out[3:1] = 3'b011;
end
D: out[3:1] = 3'b111;
endcase
end
always @(posedge clk) begin
last_state <= state;
end
always @(*) begin
if (((last_state==A) && (state==B)) || ((last_state==B) && (state==C))) begin
out[0] = 1'b1;
end
else if (((last_state==D) && (state==C)) || ((last_state==C) && (state==B))) begin
out[0] = 1'b0;
end
else if (state == D) begin
out[0] = 1'b1;
end
else if (state == A) begin
out[0] = 1'b0;
end
end
endmodule
//本题的关键是dfr的输出，我的想法是通过检测水位到底是由高水位降到低水位还是相反的过程，类似于边沿检测的想法
//题目的答案的想法就非常简洁，直接把高水位和低水位变化过来的当成两个状态，这样就可以直接输出结果，不需要再去判断边沿了，完美
/*
module top_module (
input clk,
input reset,
input [3:1] s,
output reg fr3,
output reg fr2,
output reg fr1,
output reg dfr
);
// Give state names and assignments. I'm lazy, so I like to use decimal numbers.
// It doesn't really matter what assignment is used, as long as they're unique.
// We have 6 states here.
parameter A2=0, B1=1, B2=2, C1=3, C2=4, D1=5;
reg [2:0] state, next; // Make sure these are big enough to hold the state encodings.
// Edge-triggered always block (DFFs) for state flip-flops. Synchronous reset.
always @(posedge clk) begin
if (reset) state <= A2;
else state <= next;
end
// Combinational always block for state transition logic. Given the current state and inputs,
// what should be next state be?
// Combinational always block: Use blocking assignments.
always@(*) begin
case (state)
A2: next = s[1] ? B1 : A2;
B1: next = s[2] ? C1 : (s[1] ? B1 : A2);
B2: next = s[2] ? C1 : (s[1] ? B2 : A2);
C1: next = s[3] ? D1 : (s[2] ? C1 : B2);
C2: next = s[3] ? D1 : (s[2] ? C2 : B2);
D1: next = s[3] ? D1 : C2;
default: next = 'x;
endcase
end
// Combinational output logic. In this problem, a procedural block (combinational always block)
// is more convenient. Be careful not to create a latch.
always@(*) begin
case (state)
A2: {fr3, fr2, fr1, dfr} = 4'b1111;
B1: {fr3, fr2, fr1, dfr} = 4'b0110;
B2: {fr3, fr2, fr1, dfr} = 4'b0111;
C1: {fr3, fr2, fr1, dfr} = 4'b0010;
C2: {fr3, fr2, fr1, dfr} = 4'b0011;
D1: {fr3, fr2, fr1, dfr} = 4'b0000;
default: {fr3, fr2, fr1, dfr} = 'x;
endcase
end
endmodule
*/
Lemmings1
module top_module(
input clk,
input areset, // Freshly brainwashed Lemmings walk left.
input bump_left,
input bump_right,
output walk_left,
output walk_right); //
parameter LEFT=1'b0, RIGHT=1'b1;
reg state, next_state;
always @(*) begin
// State transition logic
case (state)
LEFT:next_state = (bump_left) ? RIGHT : LEFT;
RIGHT:next_state = (bump_right) ? LEFT : RIGHT;
endcase
end
always @(posedge clk, posedge areset) begin
// State flip-flops with asynchronous reset
if (areset) begin
state <= LEFT;
end
else
state <= next_state;
end
// Output logic
assign walk_left = (state == LEFT);
assign walk_right = (state == RIGHT);
endmodule
/*
module top_module (
input clk,
input areset,
input bump_left,
input bump_right,
output walk_left,
output walk_right
);
// Give state names and assignments. I'm lazy, so I like to use decimal numbers.
// It doesn't really matter what assignment is used, as long as they're unique.
parameter WL=0, WR=1;
reg state;
reg next;
// Combinational always block for state transition logic. Given the current state and inputs,
// what should be next state be?
// Combinational always block: Use blocking assignments.
always@(*) begin
case (state)
WL: next = bump_left ? WR : WL;
WR: next = bump_right ? WL : WR;
endcase
end
// Combinational always block for state transition logic. Given the current state and inputs,
// what should be next state be?
// Combinational always block: Use blocking assignments.
always @(posedge clk, posedge areset) begin
if (areset) state <= WL;
else state <= next;
end
// Combinational output logic. In this problem, an assign statement are the simplest.
// In more complex circuits, a combinational always block may be more suitable.
assign walk_left = (state==WL);
assign walk_right = (state==WR);
endmodule
*/
Lemmings2
module top_module(
input clk,
input areset, // Freshly brainwashed Lemmings walk left.
input bump_left,
input bump_right,
input ground,
output walk_left,
output walk_right,
output aaah );
parameter LEFT=2'd0,RIGHT=2'd1,LEFT_FALL=2'd2,RIGHT_FALL=2'd3;
reg [1:0] state,next_state;
always @( *) begin
case (state)
LEFT:
begin
if (!ground) begin
next_state = LEFT_FALL;
end
else if (bump_left) begin
next_state = RIGHT;
end
else
next_state = LEFT;
end
RIGHT:
begin
if (!ground) begin
next_state = RIGHT_FALL;
end
else if (bump_right) begin
next_state = LEFT;
end
else
next_state = RIGHT;
end
LEFT_FALL:
begin
if (ground) begin
next_state = LEFT;
end
else
next_state = LEFT_FALL;
end
RIGHT_FALL:
begin
if (ground) begin
next_state = RIGHT;
end
else
next_state = RIGHT_FALL;
end
endcase
end
always @(posedge clk or posedge areset) begin
if (areset) begin
state <= LEFT;
end
else
state <= next_state;
end
assign walk_left = (state == LEFT);
assign walk_right = (state == RIGHT);
assign aaah = (state == RIGHT_FALL || state == LEFT_FALL);
endmodule
Lemmings3
module top_module(
input clk,
input areset, // Freshly brainwashed Lemmings walk left.
input bump_left,
input bump_right,
input ground,
input dig,
output walk_left,
output walk_right,
output aaah,
output digging );
parameter LEFT=3'd0,RIGHT=3'd1,LEFT_FALL=3'd2,RIGHT_FALL=3'd3,LEFT_DIG=3'd4,RIGHT_DIG=3'd5;
reg [2:0] state,next_state;
always @( *) begin
case (state)
LEFT:
begin
if (!ground) begin
next_state = LEFT_FALL;
end
else if(dig) begin
next_state = LEFT_DIG;
end
else if (bump_left) begin
next_state = RIGHT;
end
else
next_state = LEFT;
end
RIGHT:
begin
if (!ground) begin
next_state = RIGHT_FALL;
end
else if(dig) begin
next_state = RIGHT_DIG;
end
else if (bump_right) begin
next_state = LEFT;
end
else
next_state = RIGHT;
end
LEFT_FALL:
begin
if (ground) begin
next_state = LEFT;
end
else
next_state = LEFT_FALL;
end
RIGHT_FALL:
begin
if (ground) begin
next_state = RIGHT;
end
else
next_state = RIGHT_FALL;
end
LEFT_DIG:
begin
if (!ground) begin
next_state = LEFT_FALL;
end
else
next_state = LEFT_DIG;
end
RIGHT_DIG:
begin
if (!ground) begin
next_state = RIGHT_FALL;
end
else
next_state = RIGHT_DIG;
end
endcase
end
always @(posedge clk or posedge areset) begin
if (areset) begin
state <= LEFT;
end
else
state <= next_state;
end
assign walk_left = (state == LEFT);
assign walk_right = (state == RIGHT);
assign aaah = (state == RIGHT_FALL || state == LEFT_FALL);
assign digging = (state == RIGHT_DIG || state == LEFT_DIG);
endmodule
Lemmings4
//这种方式的想法是在检测到计数器已经计数到了20，但是还是没有地面，因此在此之后旅鼠就一定会死了，这时跳转到SPLATTER状态，
//在这个状态再去判断是否接触到地面，这时就不用再计数了，真正实现了下落时间无限长
module top_module(
input clk,
input areset, // Freshly brainwashed Lemmings walk left.
input bump_left,
input bump_right,
input ground,
input dig,
output reg walk_left,
output reg walk_right,
output reg aaah,
output reg digging );
parameter LEFT=3'd0,RIGHT=3'd1,LEFT_FALL=3'd2,RIGHT_FALL=3'd3,LEFT_DIG=3'd4,RIGHT_DIG=3'd5,SPLATTER=3'd6,DEAD=3'd7;
reg [2:0] state,next_state;
reg [4:0] count;
always @(posedge clk or posedge areset) begin
if (areset) begin
count <= 21'b0;
end
else if (next_state == RIGHT_FALL || next_state == LEFT_FALL) begin
count <= count + 1'b1;
end
else
count <= 21'b0;
end
always @( *) begin
case (state)
LEFT:
begin
if (!ground) begin
next_state = LEFT_FALL;
end
else if(dig) begin
next_state = LEFT_DIG;
end
else if (bump_left) begin
next_state = RIGHT;
end
else
next_state = LEFT;
end
RIGHT:
begin
if (!ground) begin
next_state = RIGHT_FALL;
end
else if(dig) begin
next_state = RIGHT_DIG;
end
else if (bump_right) begin
next_state = LEFT;
end
else
next_state = RIGHT;
end
LEFT_FALL:
begin
if (ground) begin
next_state = LEFT;
end
else
begin
if (count >= 20) begin
next_state = SPLATTER;
end
else
next_state = LEFT_FALL;
end
end
RIGHT_FALL:
begin
if (ground) begin
next_state = RIGHT;
end
else
begin
if (count >= 20) begin
next_state = SPLATTER;
end
else
next_state = RIGHT_FALL;
end
end
LEFT_DIG:
begin
if (!ground) begin
next_state = LEFT_FALL;
end
else
next_state = LEFT_DIG;
end
RIGHT_DIG:
begin
if (!ground) begin
next_state = RIGHT_FALL;
end
else
next_state = RIGHT_DIG;
end
SPLATTER:
begin
if (ground) begin
next_state = DEAD;
end
else
next_state = SPLATTER;
end
DEAD: next_state = DEAD;
default :
next_state = state;
endcase
end
always @(posedge clk or posedge areset) begin
if (areset) begin
state <= LEFT;
end
else
state <= next_state;
end
always @( *) begin
case (state)
DEAD:
begin
walk_left = 1'b0;
walk_right = 1'b0;
aaah = 1'b0;
digging = 1'b0;
end
SPLATTER:
begin
walk_left = 1'b0;
walk_right = 1'b0;
aaah = 1'b1;
digging = 1'b0;
end
LEFT:
begin
walk_left = 1'b1;
walk_right = 1'b0;
aaah = 1'b0;
digging = 1'b0;
end
RIGHT:
begin
walk_left = 1'b0;
walk_right = 1'b1;
aaah = 1'b0;
digging = 1'b0;
end
LEFT_FALL:
begin
walk_left = 1'b0;
walk_right = 1'b0;
aaah = 1'b1;
digging = 1'b0;
end
RIGHT_FALL:
begin
walk_left = 1'b0;
walk_right = 1'b0;
aaah = 1'b1;
digging = 1'b0;
end
LEFT_DIG:
begin
walk_left = 1'b0;
walk_right = 1'b0;
aaah = 1'b0;
digging = 1'b1;
end
RIGHT_DIG:
begin
walk_left = 1'b0;
walk_right = 1'b0;
aaah = 1'b0;
digging = 1'b1;
end
endcase
end
endmodule
/*
module top_module(
input clk,
input areset, // Freshly brainwashed Lemmings walk left.
input bump_left,
input bump_right,
input ground,
input dig,
output reg walk_left,
output reg walk_right,
output reg aaah,
output reg digging );
parameter LEFT=3'd0,RIGHT=3'd1,LEFT_FALL=3'd2,RIGHT_FALL=3'd3,LEFT_DIG=3'd4,RIGHT_DIG=3'd5,SPLATTER=3'd6;
reg [2:0] state,next_state;
reg [20:0] count;
always @(posedge clk or posedge areset) begin
if (areset) begin
count <= 21'b0;
end
else if (next_state == RIGHT_FALL || next_state == LEFT_FALL) begin
count <= count + 1'b1;
end
else
count <= 21'b0;
end
always @( *) begin
case (state)
LEFT:
begin
if (!ground) begin
next_state = LEFT_FALL;
end
else if(dig) begin
next_state = LEFT_DIG;
end
else if (bump_left) begin
next_state = RIGHT;
end
else
next_state = LEFT;
end
RIGHT:
begin
if (!ground) begin
next_state = RIGHT_FALL;
end
else if(dig) begin
next_state = RIGHT_DIG;
end
else if (bump_right) begin
next_state = LEFT;
end
else
next_state = RIGHT;
end
LEFT_FALL:
begin
if (ground) begin
if (count <= 21'd20) begin
next_state = LEFT;
end
else
next_state = SPLATTER;
end
else
next_state = LEFT_FALL;
end
RIGHT_FALL:
begin
if (ground) begin
if (count <= 21'd20) begin
next_state = RIGHT;
end
else
next_state = SPLATTER;
end
else
next_state = RIGHT_FALL;
end
LEFT_DIG:
begin
if (!ground) begin
next_state = LEFT_FALL;
end
else
next_state = LEFT_DIG;
end
RIGHT_DIG:
begin
if (!ground) begin
next_state = RIGHT_FALL;
end
else
next_state = RIGHT_DIG;
end
SPLATTER:
next_state = SPLATTER;
default :
next_state = state;
endcase
end
always @(posedge clk or posedge areset) begin
if (areset) begin
state <= LEFT;
end
else
state <= next_state;
end
always @( *) begin
case (state)
SPLATTER:
begin
walk_left = 1'b0;
walk_right = 1'b0;
aaah = 1'b0;
digging = 1'b0;
end
LEFT:
begin
walk_left = 1'b1;
walk_right = 1'b0;
aaah = 1'b0;
digging = 1'b0;
end
RIGHT:
begin
walk_left = 1'b0;
walk_right = 1'b1;
aaah = 1'b0;
digging = 1'b0;
end
LEFT_FALL:
begin
walk_left = 1'b0;
walk_right = 1'b0;
aaah = 1'b1;
digging = 1'b0;
end
RIGHT_FALL:
begin
walk_left = 1'b0;
walk_right = 1'b0;
aaah = 1'b1;
digging = 1'b0;
end
LEFT_DIG:
begin
walk_left = 1'b0;
walk_right = 1'b0;
aaah = 1'b0;
digging = 1'b1;
end
RIGHT_DIG:
begin
walk_left = 1'b0;
walk_right = 1'b0;
aaah = 1'b0;
digging = 1'b1;
end
endcase
end
endmodule
*/
/*
这是第一次的版本，我把count设置为5位的寄存器，但是提交之后一直都无法通过，折腾了好长时间，分析了各种问题，一度以为是网站有问题，因为逻辑上完全没问题的，
经过上网搜索一番后我终于意识到了问题在哪，题目中说的是下落的时间可以无限长，如果我设置的是5位的寄存器的话，计数只能记32个，
一旦下落的时间超过了32个周期的话计数器就归零了，这样的话就不对了，这也是C语言的后遗症了感觉，经常忽略寄存器的位数问题，
所以我在下一次提交直接把位数改到了21位，果不其然通过了验证，因为网站不可能真的无限进行下去，只要的计数够多就可以，但是这属于作弊。
module top_module(
input clk,
input areset, // Freshly brainwashed Lemmings walk left.
input bump_left,
input bump_right,
input ground,
input dig,
output reg walk_left,
output reg walk_right,
output reg aaah,
output reg digging );
parameter LEFT=3'd0,RIGHT=3'd1,LEFT_FALL=3'd2,RIGHT_FALL=3'd3,LEFT_DIG=3'd4,RIGHT_DIG=3'd5,SPLATTER=3'd6;
reg [2:0] state,next_state;
reg [4:0] count;
always @(posedge clk or posedge areset) begin
if (areset) begin
count <= 5'b0;
end
else if (next_state == RIGHT_FALL || next_state == LEFT_FALL) begin
count <= count + 1'b1;
end
else
count <= 5'b0;
end
always @( *) begin
case (state)
LEFT:
begin
if (!ground) begin
next_state = LEFT_FALL;
end
else if(dig) begin
next_state = LEFT_DIG;
end
else if (bump_left) begin
next_state = RIGHT;
end
else
next_state = LEFT;
end
RIGHT:
begin
if (!ground) begin
next_state = RIGHT_FALL;
end
else if(dig) begin
next_state = RIGHT_DIG;
end
else if (bump_right) begin
next_state = LEFT;
end
else
next_state = RIGHT;
end
LEFT_FALL:
begin
if (ground) begin
if (count <= 5'd20) begin
next_state = LEFT;
end
else
next_state = SPLATTER;
end
else
next_state = LEFT_FALL;
end
RIGHT_FALL:
begin
if (ground) begin
if (count <= 5'd20) begin
next_state = RIGHT;
end
else
next_state = SPLATTER;
end
else
next_state = RIGHT_FALL;
end
LEFT_DIG:
begin
if (!ground) begin
next_state = LEFT_FALL;
end
else
next_state = LEFT_DIG;
end
RIGHT_DIG:
begin
if (!ground) begin
next_state = RIGHT_FALL;
end
else
next_state = RIGHT_DIG;
end
SPLATTER:
next_state = SPLATTER;
default :
next_state = state;
endcase
end
always @(posedge clk or posedge areset) begin
if (areset) begin
state <= LEFT;
end
else
state <= next_state;
end
always @( *) begin
case (state)
SPLATTER:
begin
walk_left = 1'b0;
walk_right = 1'b0;
aaah = 1'b0;
digging = 1'b0;
end
LEFT:
begin
walk_left = 1'b1;
walk_right = 1'b0;
aaah = 1'b0;
digging = 1'b0;
end
RIGHT:
begin
walk_left = 1'b0;
walk_right = 1'b1;
aaah = 1'b0;
digging = 1'b0;
end
LEFT_FALL:
begin
walk_left = 1'b0;
walk_right = 1'b0;
aaah = 1'b1;
digging = 1'b0;
end
RIGHT_FALL:
begin
walk_left = 1'b0;
walk_right = 1'b0;
aaah = 1'b1;
digging = 1'b0;
end
LEFT_DIG:
begin
walk_left = 1'b0;
walk_right = 1'b0;
aaah = 1'b0;
digging = 1'b1;
end
RIGHT_DIG:
begin
walk_left = 1'b0;
walk_right = 1'b0;
aaah = 1'b0;
digging = 1'b1;
end
endcase
end
endmodule
*/
Fsm onehot
module top_module(
input in,
input [9:0] state,
output reg [9:0] next_state,
output out1,
output out2);
parameter S0=4'd0,S1=4'd1,S2=4'd2,S3=4'd3,S4=4'd4,S5=4'd5,S6=4'd6,S7=4'd7,S8=4'd8,S9=4'd9;
always @( *) begin
next_state[S0] = state[S0]&~in | state[S1]&~in | state[S2]&~in | state[S3]&~in | state[S4]&~in | state[S7]&~in | state[S8]&~in | state[S9]&~in;
next_state[S1] = state[S0]&in | state[S8]&in | state[S9]∈
next_state[S2] = state[S1]∈
next_state[S3] = state[S2]∈
next_state[S4] = state[S3]∈
next_state[S5] = state[S4]∈
next_state[S6] = state[S5]∈
next_state[S7] = state[S6]&in | state[S7]∈
next_state[S8] = state[S5]&~in;
next_state[S9] = state[S6]&~in;
end
assign out1 = state[S8] | state[S9];
assign out2 = state[S7] | state[S9];
endmodule
Fsm ps2
module top_module(
input clk,
input [7:0] in,
input reset, // Synchronous reset
output reg done); //
parameter BYTE1=2'd1,BYTE2=2'd2,BYTE3=2'd3;
reg [1:0] state,next_state;
// State transition logic (combinational)
always @( *) begin
case (state)
BYTE1: next_state = (in[3]==1'b1) ? BYTE2 : BYTE1;
BYTE2:next_state = BYTE3;
BYTE3:next_state = BYTE1;
endcase
end
// State flip-flops (sequential)
always @(posedge clk) begin
if (reset) begin
state <= BYTE1;
end
else
state <= next_state;
end
// Output logic
always @(posedge clk) begin
if (reset) begin
done <= 1'b0;
end
else if (state == BYTE3) begin
done <= 1'b1;
end
else
done <= 1'b0;
end
endmodule
Fsm ps2data
module top_module(
input clk,
input [7:0] in,
input reset, // Synchronous reset
output reg [23:0] out_bytes,
output reg done); //
// FSM from fsm_ps2
parameter BYTE1=2'd1,BYTE2=2'd2,BYTE3=2'd3;
reg [1:0] state,next_state;
// State transition logic (combinational)
always @( *) begin
case (state)
BYTE1: next_state = (in[3]==1'b1) ? BYTE2 : BYTE1;
BYTE2:next_state = BYTE3;
BYTE3:next_state = BYTE1;
endcase
end
// State flip-flops (sequential)
always @(posedge clk) begin
if (reset) begin
state <= BYTE1;
end
else
state <= next_state;
end
// Output logic
always @(posedge clk) begin
if (reset) begin
done <= 1'b0;
end
else if (state == BYTE3) begin
done <= 1'b1;
end
else
done <= 1'b0;
end
// New: Datapath to store incoming bytes.
always @(posedge clk) begin
if (reset) begin
out_bytes <= 24'b0;
end
else
out_bytes <= {out_bytes[15:0],in};
end
endmodule
Fsm serial
module top_module(
input clk,
input in,
input reset, // Synchronous reset
output done
);
//reg last_in;
parameter READY=2'd0,DATA=2'd1,WAIT=2'd2,STOP=2'd3;
reg [1:0] state,next_state;
reg [3:0] count;
always @(posedge clk) begin
if (reset) begin
count <= 4'd0;
end
else if (count >= 4'd8) begin
count <= 4'd0;
end
else if (state == DATA) begin
count <= count + 1'b1;
end
else
count <= 4'd0;
end
/*
always @(posedge clk) begin
last_in <= in;
end
*/
always @( *) begin
case (state)
READY: next_state = (/*last_in &&*/ ~in) ? DATA : READY;
DATA: next_state = (count == 4'd8) ? ((in==1'b1) ? STOP : WAIT) : DATA;
WAIT: next_state = (in) ? READY : WAIT;
STOP:next_state = (in) ? READY : DATA;
endcase
end
always @(posedge clk) begin
if (reset) begin
state <= READY;
end
else
state <= next_state;
end
assign done = (state == STOP);
endmodule
如果用边沿检测的话就出如下的问题。
Fsm serialdata
module top_module(
input clk,
input in,
input reset, // Synchronous reset
output reg [7:0] out_byte,
output done
); //
// Use FSM from Fsm_serial
parameter READY=2'd0,DATA=2'd1,WAIT=2'd2,STOP=2'd3;
reg [1:0] state,next_state;
reg [3:0] count;
always @(posedge clk) begin
if (reset) begin
count <= 4'd0;
end
else if (count >= 4'd8) begin
count <= 4'd0;
end
else if (state == DATA) begin
count <= count + 1'b1;
end
else
count <= 4'd0;
end
/*
always @(posedge clk) begin
last_in <= in;
end
*/
always @( *) begin
case (state)
READY: next_state = (/*last_in &&*/ ~in) ? DATA : READY;
DATA: next_state = (count == 4'd8) ? ((in==1'b1) ? STOP : WAIT) : DATA;
WAIT: next_state = (in) ? READY : WAIT;
STOP:next_state = (in) ? READY : DATA;
endcase
end
always @(posedge clk) begin
if (reset) begin
state <= READY;
end
else
state <= next_state;
end
assign done = (state == STOP);
// New: Datapath to latch input bits.
always @(posedge clk) begin
if (state == DATA && count <= 4'd7) begin
out_byte <= {in,out_byte[7:1]};
end
end
endmodule
Fsm serialdp
module top_module(
input clk,
input in,
input reset, // Synchronous reset
output [7:0] out_byte,
output done
); //
// Modify FSM and datapath from Fsm_serialdata
parameter READY=2'd0,DATA=2'd1,WAIT=2'd2,STOP=2'd3;
reg [1:0] state,next_state;
reg [3:0] count;
reg [8:0] out_byte1;
wire parity_reset,odd;
always @(posedge clk) begin
if (reset) begin
count <= 4'd0;
end
else if (count >= 4'd9) begin
count <= 4'd0;
end
else if (state == DATA) begin
count <= count + 1'b1;
end
else
count <= 4'd0;
end
/*
always @(posedge clk) begin
last_in <= in;
end
*/
assign parity_reset = (state == DATA) ? 1'b0 : 1'b1;
parity u_parity(
.clk(clk),
.reset(parity_reset),
.in(in),
.odd(odd)
);
always @( *) begin
case (state)
READY: next_state = (/*last_in &&*/ ~in) ? DATA : READY;
DATA: next_state = (count == 4'd9) ? ((in==1'b1) ? STOP : WAIT) : DATA;
WAIT: next_state = (in) ? READY : WAIT;
STOP:next_state = (in) ? READY : DATA;
endcase
end
always @(posedge clk) begin
if (reset) begin
state <= READY;
end
else
state <= next_state;
end
assign done = (state == STOP & odd == 1'b0);
// New: Datapath to latch input bits.
always @(posedge clk) begin
if (state == DATA && count <= 4'd8) begin
out_byte1 <= {in,out_byte1[8:1]};
end
end
assign out_byte = out_byte1[7:0];
// New: Add parity checking.
endmodule
Fsm hdlc
module top_module(
input clk,
input reset, // Synchronous reset
input in,
output disc,
output flag,
output err);
parameter IDLE=3'd0,DISC=3'd1,FLAG=3'd2,ERR=3'd3,ONE=3'd4;
reg [2:0] state,next_state;
reg [3:0] count;
always @(posedge clk) begin
if (reset) begin
count <= 4'b0;
end
else if (in) begin
count <= count +1'b1;
end
else if (~in) begin
count <= 4'b0;
end
end
always @(*) begin
case (state)
IDLE: next_state = (in) ? ONE : IDLE;
ONE:
begin
if (~in & count == 4'd5) begin
next_state = DISC;
end
else if(~in & count == 4'd6) begin
next_state = FLAG;
end
else if(in & count == 4'd6) begin
next_state = ERR;
end
else if(~in) begin
next_state = IDLE;
end
else
next_state = ONE;
end
DISC:
begin
if (in) begin
next_state = ONE;
end
else
next_state = IDLE;
end
FLAG:
begin
if (in) begin
next_state = ONE;
end
else
next_state = IDLE;
end
ERR:
begin
if (~in) begin
next_state = IDLE;
end
else
next_state = ERR;
end
default :
next_state = IDLE;
endcase
end
always @(posedge clk) begin
if (reset) begin
state <= IDLE;
end
else
state <= next_state;
end
assign disc = (state == DISC);
assign flag = (state == FLAG);
assign err = (state == ERR);
endmodule
ece241 2013 q8
module top_module (
input clk,
input aresetn, // Asynchronous active-low reset
input x,
output z );
parameter A=2'd0,B=2'd1,C=2'd2;
reg [1:0] state,next_state;
always @( *) begin
case (state)
A: next_state = (x) ? B : A;
B: next_state = (x) ? B : C;
C: next_state = (x) ? B : A;
default :
next_state = A;
endcase
end
always @(posedge clk or negedge aresetn) begin
if (~aresetn) begin
state <= A;
end
else
state <= next_state;
end
assign z = (state == C && x);
endmodule
/*
module top_module (
input clk,
input aresetn,
input x,
output reg z
);
// Give state names and assignments. I'm lazy, so I like to use decimal numbers.
// It doesn't really matter what assignment is used, as long as they're unique.
parameter S=0, S1=1, S10=2;
reg[1:0] state, next; // Make sure state and next are big enough to hold the state encodings.
// Edge-triggered always block (DFFs) for state flip-flops. Asynchronous reset.
always@(posedge clk, negedge aresetn)
if (!aresetn)
state <= S;
else
state <= next;
// Combinational always block for state transition logic. Given the current state and inputs,
// what should be next state be?
// Combinational always block: Use blocking assignments.
always@(*) begin
case (state)
S: next = x ? S1 : S;
S1: next = x ? S1 : S10;
S10: next = x ? S1 : S;
default: next = 'x;
endcase
end
// Combinational output logic. I used a combinational always block.
// In a Mealy state machine, the output depends on the current state *and*
// the inputs.
always@(*) begin
case (state)
S: z = 0;
S1: z = 0;
S10: z = x; // This is a Mealy state machine: The output can depend (combinational) on the input.
default: z = 1'bx;
endcase
end
endmodule
*/
ece241 2014 q5a
module top_module (
input clk,
input areset,
input x,
output z
);
//本题的意思应该是直接默认输入的数都是复数，不用管符号位，而且第一个输入也就是最低位一定是1，这样在求补码的时候，
//只有最低位是1，剩下的位直接就反就是结果了
parameter A=2'd0,B=2'd1,C=2'd2;
reg [1:0] state,next_state;
always @( *) begin
case (state)
A:next_state = (x) ? B : A;
B:next_state = (x) ? C : B;
C:next_state = (x) ? C : B;
default :
next_state = A;
endcase
end
always @(posedge clk or posedge areset) begin
if (areset) begin
state <= A;
end
else
state <= next_state;
end
assign z = (state == B);
endmodule
ece241 2014 q5b
module top_module (
input clk,
input areset,
input x,
output reg z
);
parameter A = 1'b0,B = 1'b1;
reg [1:0] state,next_state;
always @( *) begin
next_state[A] = state[A] & ~x;
next_state[B] = (state[A] & x) || (state[B]);
end
always @(posedge clk or posedge areset) begin
if (areset) begin
state <= 2'b01;
end
else
state <= next_state;
end
always @( *) begin
if (state[A]) begin
z = x;
end
else if (state[B]) begin
z = ~x;
end
else
z = 1'b0;
end
endmodule
2014 q3fsm
module top_module (
input clk,
input reset, // Synchronous reset
input s,
input w,
output reg z
);
parameter A=1'b0,B=1'b1;
reg state,next_state;
reg [1:0] count,num;
always @( *) begin
case (state)
A: next_state = (s) ? B : A;
B: next_state = B;
endcase
end
always @(posedge clk) begin
if (reset) begin
state <= A;
end
else
state <= next_state;
end
always @(posedge clk) begin
if (reset) begin
count <= 2'b0;
end
else if(state == B) begin
if (count == 2'd2) begin
count <= 2'b0;
end
else
count <= count + 1'b1;
end
else
count <= 2'b0;
end
always @(posedge clk) begin
if (reset) begin
num <= 2'b0;
end
else if (state == B) begin
if (count == 2'd2) begin
num <= 2'b0;
end
else
num <= num + w;
end
else
num <= 2'b0;
end
always @(posedge clk) begin
if (reset) begin
z <= 1'b0;
end
else if ((count == 2'd2) && ((num == 2'd1 && w) || (num == 2'd2 && ~w))) begin
z <= 1'b1;
end
else
z <= 1'b0;
end
endmodule
2014 q3bfsm
module top_module (
input clk,
input reset, // Synchronous reset
input x,
output z
);
parameter S1=3'b000,S2=3'b001,S3=3'b010,S4=3'b011,S5=3'b100;
reg [2:0] state,next_state;
always @(*) begin
case (state)
S1: next_state = (x) ? S2 : S1;
S2: next_state = (x) ? S5 : S2;
S3: next_state = (x) ? S2 : S3;
S4: next_state = (x) ? S3 : S2;
S5: next_state = (x) ? S5 : S4;
default :
next_state = S1;
endcase
end
always @(posedge clk) begin
if (reset) begin
state <= S1;
end
else
state <= next_state;
end
assign z = (state == S4 || state == S5);
endmodule
2014 q3c
module top_module (
input clk,
input [2:0] y,
input x,
output Y0,
output z
);
//这题好像和时钟没关系
parameter S1=3'b000,S2=3'b001,S3=3'b010,S4=3'b011,S5=3'b100;
reg [2:0] next_state;
always @(*) begin
case (y)
S1: next_state = (x) ? S2 : S1;
S2: next_state = (x) ? S5 : S2;
S3: next_state = (x) ? S2 : S3;
S4: next_state = (x) ? S3 : S2;
S5: next_state = (x) ? S5 : S4;
default :
next_state = S1;
endcase
end
assign z = (y == S4 || y == S5);
assign Y0 = next_state[0];
endmodule
m2014 q6b
module top_module (
input [3:1] y,
input w,
output Y2);
parameter A=3'b000,B=3'b001,C=3'b010,D=3'b011,E=3'b100,F=3'b101;
reg [2:0] next_state;
always @( *) begin
case (y)
A: next_state = (w) ? A : B;
B: next_state = (w) ? D : C;
C: next_state = (w) ? D : E;
D: next_state = (w) ? A : F;
E: next_state = (w) ? D : E;
F: next_state = (w) ? D : C;
endcase
end
assign Y2 = next_state[1];
endmodule
m2014 q6c
module top_module (
input [6:1] y,
input w,
output Y2,
output Y4);
parameter A=3'd1,B=3'd2,C=3'd3,D=3'd4,E=3'd5,F=33'd6;
wire [6:1] next_state;
assign next_state[A] = y[A]&w || y[D]&w;
assign next_state[B] = y[A]&~w;
assign next_state[C] = y[B]&~w || y[F]&~w;
assign next_state[D] = y[B]&w || y[C]&w || y[E]&w || y[F]&w;
assign next_state[E] = y[C]&~w || y[E]&~w;
assign next_state[F] = y[D]&~w;
assign Y2 = next_state[2];
assign Y4 = next_state[4];
endmodule
m2014 q6
module top_module (
input clk,
input reset, // synchronous reset
input w,
output z);
parameter A=3'd1,B=3'd2,C=3'd3,D=3'd4,E=3'd5,F=33'd6;
wire [6:1] next_state;
reg [6:1] state;
assign next_state[A] = state[A]&w || state[D]&w;
assign next_state[B] = state[A]&~w;
assign next_state[C] = state[B]&~w || state[F]&~w;
assign next_state[D] = state[B]&w || state[C]&w || state[E]&w || state[F]&w;
assign next_state[E] = state[C]&~w || state[E]&~w;
assign next_state[F] = state[D]&~w;
always @(posedge clk) begin
if (reset) begin
state <= 6'b000001;
end
else
state <= next_state;
end
assign z = (state[F] || state[E]);
endmodule
2012 q2fsm
module top_module (
input clk,
input reset, // Synchronous active-high reset
input w,
output z
);
parameter A=3'b000,B=3'b001,C=3'b010,D=3'b011,E=3'b100,F=3'b101;
reg [2:0] state,next_state;
always @( *) begin
case (state)
A: next_state = (~w) ? A : B;
B: next_state = (~w) ? D : C;
C: next_state = (~w) ? D : E;
D: next_state = (~w) ? A : F;
E: next_state = (~w) ? D : E;
F: next_state = (~w) ? D : C;
endcase
end
always @(posedge clk) begin
if (reset) begin
state <= A;
end
else
state <= next_state;
end
assign z = (state == F || state == E);
endmodule
2012 q2b
module top_module (
input [5:0] y,
input w,
output Y1,
output Y3
);
parameter A=3'd0,B=3'd1,C=3'd2,D=3'd3,E=3'd4,F=33'd5;
wire [5:0] next_state;
assign next_state[A] = y[A]&~w || y[D]&~w;
assign next_state[B] = y[A]&w;
assign next_state[C] = y[B]&w || y[F]&w;
assign next_state[D] = y[B]&~w || y[C]&~w || y[E]&~w || y[F]&~w;
assign next_state[E] = y[C]&w || y[E]&w;
assign next_state[F] = y[D]&w;
assign Y1 = next_state[1];
assign Y3 = next_state[3];
endmodule
2013 q2afsm
module top_module (
input clk,
input resetn, // active-low synchronous reset
input [3:1] r, // request
output [3:1] g // grant
);
parameter A=2'b00,B=2'b01,C=2'b10,D=2'b11;
reg [1:0] state,next_state;
always @( *) begin
case (state)
A:
begin
if (r == 3'b000) begin
next_state = A;
end
else if(r[1] == 1'b1) begin
next_state = B;
end
else if(r[2:1] == 2'b10) begin
next_state = C;
end
else if(r == 3'b100) begin
next_state = D;
end
else
next_state = A;
end
B: next_state = (r[1]) ? B : A;
C: next_state = (r[2]) ? C : A;
D: next_state = (r[3]) ? D : A;
default :
next_state = A;
endcase
end
always @(posedge clk) begin
if (!resetn) begin
state <= A;
end
else
state <= next_state;
end
assign g[1] = (state == B);
assign g[2] = (state == C);
assign g[3] = (state == D);
endmodule
2013 q2bfsm
module top_module (
input clk,
input resetn, // active-low synchronous reset
input x,
input y,
output f,
output g
);
parameter A=4'd0,B0=4'd8,B1=4'd1,B2=4'd2,B3=4'd3,C1=4'd4,C2=4'd5,D=4'd6,E=4'd7;
reg [3:0] state,next_state;
always @( *) begin
case (state)
A: next_state = B0;
B0:next_state = B1;
B1:next_state = (x) ? B2 : B1;
B2:next_state = (x) ? B2 : B3;
B3:next_state = (x) ? C1 : B1;
C1:next_state = (y) ? D : C2;
C2:next_state = (y) ? D : E;
D:next_state = D;
E:next_state = E;
default :
next_state = A;
endcase
end
always @(posedge clk) begin
if (!resetn) begin
state <= A;
end
else
begin
state <= next_state;
end
end
assign f = (state == B0);
assign g = (state == D || state == C1 || state == C2);
endmodule
Building Larger Circuits
review2015 count1k
module top_module (
input clk,
input reset,
output reg [9:0] q);
always @(posedge clk) begin
if (reset) begin
q <= 10'd0;
end
else if (q == 10'd999) begin
q <= 10'd0;
end
else
q <= q + 1'b1;
end
endmodule
review2015 shiftcount
module top_module (
input clk,
input shift_ena,
input count_ena,
input data,
output reg [3:0] q);
always @(posedge clk) begin
if (shift_ena) begin
q <= {q[2:0],data};
end
else if(count_ena) begin
q <= q - 1'b1;
end
else
q <= q;
end
endmodule
review2015 fsmseq
module top_module (
input clk,
input reset, // Synchronous reset
input data,
output start_shifting);
parameter A=3'd0,B=3'd1,C=3'd2,D=3'd3,E=3'd4;
reg [2:0] state,next_state;
always @( *) begin
case (state)
A: next_state = (data) ? B : A;
B: next_state = (data) ? C : A;
C: next_state = (data) ? C : D;
D: next_state = (data) ? E : A;
E: next_state = E ;
default :
next_state = A;
endcase
end
always @(posedge clk) begin
if (reset) begin
state <= A;
end
else
state <= next_state;
end
assign start_shifting = (state == E);
endmodule
review2015 fsmshift
module top_module (
input clk,
input reset, // Synchronous reset
output shift_ena);
parameter A=3'd0,B=3'd1,C=3'd2,D=3'd3,E=3'd4;
reg [2:0] state,next_state;
always @( *) begin
case (state)
A: next_state = B;
B: next_state = C;
C: next_state = D;
D: next_state = E;
E: next_state = E;
default :
next_state = A;
endcase
end
always @(posedge clk) begin
if (reset) begin
state <= A;
end
else
state <= next_state;
end
assign shift_ena = (state == A || state == B || state == C || state == D);
endmodule
review2015 fsm
module top_module (
input clk,
input reset, // Synchronous reset
input data,
output shift_ena,
output counting,
input done_counting,
output done,
input ack );
parameter A=4'd0,B=4'd1,C=4'd2,D=4'd3,E=4'd4,F=4'd5,G=4'd6,H=4'd7,I=4'd8,J=4'd9;
reg [3:0] state,next_state;
always @( *) begin
case (state)
A: next_state = (data) ? B : A;
B: next_state = (data) ? C : A;
C: next_state = (data) ? C : D;
D: next_state = (data) ? E : A;
E: next_state = F;
F: next_state = G;
G: next_state = H;
H: next_state = I;
I: next_state = (done_counting) ? J : I;
J: next_state = (ack) ? A : J;
default :
next_state = A;
endcase
end
always @(posedge clk) begin
if (reset) begin
state <= A;
end
else
state <= next_state;
end
assign shift_ena = (state == E || state == F || state == G || state == H);
assign counting = (state == I);
assign done = (state == J);
endmodule
review2015 fancytimer
module top_module (
input clk,
input reset, // Synchronous reset
input data,
output reg [3:0] count,
output counting,
output done,
input ack );
wire shift_ena;
reg done_counting;
reg [9:0] count1;
parameter A=4'd0,B=4'd1,C=4'd2,D=4'd3,E=4'd4,F=4'd5,G=4'd6,H=4'd7,I=4'd8,J=4'd9;
reg [3:0] state,next_state;
always @( *) begin
case (state)
A: next_state = (data) ? B : A;
B: next_state = (data) ? C : A;
C: next_state = (data) ? C : D;
D: next_state = (data) ? E : A;
E: next_state = F;
F: next_state = G;
G: next_state = H;
H: next_state = I;
I: next_state = (done_counting) ? J : I;
J: next_state = (ack) ? A : J;
default :
next_state = A;
endcase
end
always @(posedge clk) begin
if (reset) begin
state <= A;
end
else
state <= next_state;
end
assign shift_ena = (state == E || state == F || state == G || state == H);
assign counting = (state == I);
assign done = (state == J);
//counter
always @(posedge clk) begin
if (reset) begin
count1 <= 10'd0;
end
else if(shift_ena) begin
count1 <= 10'd0;
end
else if (count1 == 10'd999) begin
count1 <= 10'd0;
end
else
count1 <= count1 + 1'b1;
end
always @(posedge clk) begin
if (shift_ena) begin
count <= {count[2:0],data};
end
else if(count1 == 10'd999) begin
count <= count - 1'b1;
end
else
count <= count;
end
always @(posedge clk) begin
if (reset) begin
done_counting <= 1'b0;
end
else if (count1 == 10'd998 && count == 3'b0 && state == I) begin
done_counting <= 1'b1;
end
else
done_counting <= 1'b0;
end
endmodule
review2015 fsmonehot
module top_module(
input d,
input done_counting,
input ack,
input [9:0] state, // 10-bit one-hot current state
output B3_next,
output S_next,
output S1_next,
output Count_next,
output Wait_next,
output done,
output counting,
output shift_ena
); //
// You may use these parameters to access state bits using e.g., state[B2] instead of state[6].
parameter S=0, S1=1, S11=2, S110=3, B0=4, B1=5, B2=6, B3=7, Count=8, Wait=9;
assign B3_next = state[B2];
assign S_next = state[S]&~d || state[S110]&~d || state[Wait]&ack || state[S1]&~d;
assign S1_next = state[S]&d;
assign Count_next = state[B3] || state[Count]&~done_counting;
assign Wait_next = state[Count]&done_counting || state[Wait]&~ack;
assign done = state[Wait];
assign counting = state[Count];
assign shift_ena = state[B0] || state[B1] || state[B2] || state[B3];
// assign B3_next = ...;
// assign S_next = ...;
// etc.
endmodule
Verification: Reading Simulations
Finding bugs in code
Bugs mux2
module top_module (
input sel,
input [7:0] a,
input [7:0] b,
output [7:0] out );
assign out = sel ? a : b;
endmodule
Bugs nand3
module top_module (input a, input b, input c, output out);//
wire out1;
andgate inst1 ( out1,a,b,c,1'b1,1'b1 );
assign out = ~out1;
endmodule
Bugs mux4
module top_module (
input [1:0] sel,
input [7:0] a,
input [7:0] b,
input [7:0] c,
input [7:0] d,
output [7:0] out ); //
wire [7:0] muxA, muxB;
mux2 mux0 ( sel[0], a, b, muxA );
mux2 mux1 ( sel[0], c, d, muxB );
mux2 mux2 ( sel[1], muxA, muxB, out );
endmodule
Bugs addsubz
// synthesis verilog_input_version verilog_2001
module top_module (
input do_sub,
input [7:0] a,
input [7:0] b,
output reg [7:0] out,
output reg result_is_zero
);//
always @(*) begin
case (do_sub)
0: out = a+b;
1: out = a-b;
endcase
if (out == 8'd0)
result_is_zero = 1;
else
result_is_zero = 0;
end
endmodule
Bugs case
module top_module (
input [7:0] code,
output reg [3:0] out,
output reg valid );//
always @(*)
begin
out = 0;
valid=1;
case (code)
8'h45: out = 0;
8'h16: out = 1;
8'h1e: out = 2;
8'h26: out = 3;
8'h25: out = 4;
8'h2e: out = 5;
8'h36: out = 6;
8'h3d: out = 7;
8'h3e: out = 8;
8'h46: out = 9;
default: valid = 0;
endcase
end
endmodule
Building a circuit from a simulation waveform
circuit1
module top_module (
input a,
input b,
output q );//
assign q = a & b; // Fix me
endmodule
circuit2
module top_module (
input a,
input b,
input c,
input d,
output q );//
assign q = ~a&~b&~c&~d | a&b&~c&~d | ~a&b&~c&d | a&~b&~c&d | ~a&~b&c&d | a&b&c&d | ~a&b&c&~d | a&~b&c&~d; // Fix me
endmodule
circuit3
module top_module (
input a,
input b,
input c,
input d,
output q );//
assign q = b & d | b & c | a & d | a & c;// Fix me
endmodule
circuit4
module top_module (
input a,
input b,
input c,
input d,
output q );//
assign q = b | c; // Fix me
endmodule
circuit5
module top_module (
input [3:0] a,
input [3:0] b,
input [3:0] c,
input [3:0] d,
input [3:0] e,
output reg [3:0] q );
always @( *) begin
case (c)
4'h0:q=b;
4'h1:q=e;
4'h2:q=a;
4'h3:q=d;
default :
q = 4'b1111;
endcase
end
endmodule
circuit6
module top_module (
input [2:0] a,
output reg [15:0] q );
always @( *) begin
case (a)
3'd0:q = 16'h1232;
3'd1:q = 16'haee0;
3'd2:q = 16'h27d4;
3'd3:q = 16'h5a0e;
3'd4:q = 16'h2066;
3'd5:q = 16'h64ce;
3'd6:q = 16'hc526;
3'd7:q = 16'h2f19;
default :
q = 16'h0;
endcase
end
endmodule
circuit7
module top_module (
input clk,
input a,
output reg q );
always @(posedge clk) begin
if (a) begin
q <= 1'b0;
end
else
q <= 1'b1;
end
endmodule
circuit8
module top_module (
input clock,
input a,
output reg p,
output reg q );
always @( *) begin
if (clock) begin
p = a;
end
end
always @(negedge clock) begin
q <= p;
//这是一开始的想法 q <= ~q;
end
endmodule
circuit9
module top_module (
input clk,
input a,
output reg [3:0] q );
always @(posedge clk) begin
if (a) begin
q <= 4'd4;
end
else
begin
if (q == 4'd6) begin
q <= 4'd0;
end
else
q <= q + 1'b1;
end
end
endmodule
circuit10
module top_module (
input clk,
input a,
input b,
output q,
output reg state );
assign q = (a ^ b) ^ state;
always @(posedge clk) begin
if (a==0 && b==0) begin
state <= 1'b0;
end
else if (a==1 && b==1) begin
state <= 1'b1;
end
else
state <= state;
end
endmodule
Verfication: Writing Testbenches
clock
`timescale 1ps / 1ps
module top_module ( );
reg clk;
dut u_dut( .clk(clk) ) ;
initial begin
clk = 1'b0;
forever begin
#(5) clk = ~clk;
end
end
endmodule
tb1
`timescale 1ps / 1ps
module top_module ( output reg A, output reg B );//
// generate input patterns here
initial begin
A = 1'b0;
B = 1'b0;
#10;
A = 1'b1;
#5;
B = 1'b1;
#5;
A = 1'b0;
#20;
B = 1'b0;
end
endmodule
and
`timescale 1ps/1ps
module top_module();
reg [1:0] in;
wire out;
andgate u_andgate(
.in(in),
.out(out)
);
initial begin
in = 2'b00;
#10;
in[0] = 1'b1;
#10;
in[0] = 1'b0;
in[1] = 1'b1;
#10;
in[0] = 1'b1;
end
endmodule
tb2
`timescale 1ps/1ps
module top_module();
reg [2:0] s;
reg clk,in;
wire out;
q7 u_q7(
.clk(clk),
.in(in),
.s(s),
.out(out)
);
initial begin
clk = 1'b0;
forever begin
#5;
clk = ~clk;
end
end
initial begin
in = 1'b0;
s = 3'd2;
#10;
s = 3'd6;
#10;
s = 3'd2;
in = 1'b1;
#10;
s = 3'd7;
in = 1'b0;
#10;
s = 3'd0;
in = 1'b1;
#30;
in = 1'b0;
end
endmodule
tff
`timescale 1ps/1ps
module top_module ();
reg clk,reset,t;
wire q;
tff u_tff(
.clk(clk),
.reset(reset),
.t(t),
.q(q)
);
initial begin
clk = 1'b0;
forever begin
#5;
clk = ~clk;
end
end
initial begin
reset = 1'b0;
t = 1'b0;
#10;
reset = 1'b1;
#10;
reset = 1'b0;
t = 1'b1;
end
endmodule
//reset the T flip-flop then toggle it to the "1" state.意思是把t置1
最后
有始有终，断断续续用了一个月左右的时间才完成。希望可以坚持学习，持续进步。