I have the main module with FIFO stuff.
Here it is:
module syn_fifo #(
parameter DATA_WIDTH = 8, // inpit capacity
parameter DATA_DEPTH = 8 // the depth of the FIFO
)
(
input wire clk,
input wire rst,
// Write_______________________________________________
input wire [DATA_WIDTH-1:0]din, // the input data
input wire wren, // Write anable
output wire full,
// Read________________________________________________
output wire [DATA_WIDTH-1:0]dout, // The output data
input wire rden, // Read enable
output wire empty
);
integer q_size; // The queue size(length)
integer golova; // The queue beginning
integer hvost; // The end of queue
reg [DATA_WIDTH-1:0]fifo[DATA_DEPTH-1:0];
assign full = (q_size == DATA_DEPTH) ? 1'b1: 1'b0; // FIFO is full
/*
True { full = (q_size==DATA_TEPTH) = 1 }, then wire "full" goes to "1" value
False { full = (q_size==DATA_TEPTH) = 0 }, then wire "full" goes to "0" value
*/
assign empty = (golova == hvost); // FIFO is empty
assign dout = fifo[hvost]; // FWFT (other write mode)
integer i;
//___________(The queue fullness)___________________
always #(posedge clk or posedge rst)
begin
if (rst == 1'b1)
begin
for (i = 0; i < DATA_DEPTH; i = i + 1) // incrementing the FIFO
fifo[i] <= 0; // Resetting the FIFO
golova <= 0; // Resetting the queue start variable
end
else
begin //Write_______________________________________
if (wren && ~full)
begin
fifo[golova] <= din; // putting data in to the golova
if (golova == DATA_DEPTH-1) // restrictions for the queue beginning
golova <= 0; // Reset the beginning
else
golova <= golova + 1; // other occurence incrementing
end
end
end
//Reading
always #(posedge clk or posedge rst)
begin
if (rst == 1'b1)
begin
hvost <= 0;
end
else
begin
if (rden && !empty)
/*for staying inside the queue limits - make the check of non equality of the "hvost" & "queue size"*/
begin
if (hvost == DATA_DEPTH-1) // if hvost = DATA_DEPTH-1, then
hvost <= 0; // Reset hvost
else
hvost <= hvost + 1;
end
end
end
always # (posedge clk)
begin
if (rst == 1'b1) begin
q_size <= 0;
end
else
begin
case ({wren && ~full, rden && ~empty} )
2'b01: q_size <= q_size + 1; // RO
2'b10: q_size <= q_size - 1; // WO
default: q_size <= q_size; // read and write at the same time
endcase
end
end
endmodule
Also i've got the testbench module down delow:
`timescale 1ns / 1ps
module fifo_tb();
localparam CLK_PERIOD = 10;
reg clk;
reg rst;
always begin
clk <= 1'b0;
#(CLK_PERIOD / 2);
clk <= 1'b1;
#(CLK_PERIOD / 2);
end
localparam DATA_WIDTH = 8;
localparam DATA_DEPTH = 4;
reg [DATA_WIDTH-1:0]din;
reg wren;
reg rden;
wire [DATA_WIDTH-1:0]dout;
wire empty;
wire full;
wire wr_valid;
wire rd_valid;
task write;
input integer length;
begin
if (length) begin
#(posedge clk);
wren <= 1'b1;
while (length) begin
#(posedge clk);
if (wr_valid) begin
length <= length - 1;
if (length == 1) begin
wren <= 1'b0;
end
end
end
end
end
endtask
task read;
input integer length;
begin
if (length) begin
#(posedge clk);
rden <= 1'b1;
while (length) begin
#(posedge clk);
if (rd_valid) begin
length <= length - 1;
if (length == 1) begin
rden <= 1'b0;
end
end
end
end
end
endtask
initial begin
rst <= 1'b0;
wren <= 1'b0;
rden <= 1'b0;
#50;
rst <= 1'b1;
#50;
rst <= 1'b0;
#200;
/* Test Start */
//write(4);
//read(4);
/* Test Stop */
#1000;
$finish;
end
assign wr_valid = wren & ~full;
assign rd_valid = rden & ~empty;
always #(posedge clk) begin
if (rst == 1'b1) begin
din <= 0;
end else begin
if (wr_valid == 1'b1) begin
din <= din + 1;
end
end
end
// write?
always begin
#400;
write(5);
#15;
write(7);
#25;
write(3);
#15;
write(9);
#15;
write(1);
#10000;
end
// read?
always begin
#420;
read(3);
#37;
read(13);
#21;
read(7);
#15;
read(9);
#15;
read(4);
#20;
read(7);
#10000;
end
initial begin
$dumpfile("test.vcd");
$dumpvars(0,fifo_tb);
end
syn_fifo #(.DATA_WIDTH(DATA_WIDTH),
.DATA_DEPTH(DATA_DEPTH)) dut ( .clk(clk),
.rst(rst),
.din(din),
.wren(wren),
.full(full),
.dout(dout),
.rden(rden),
.empty(empty));
endmodule
Trying to compile all of it with iVerilog + GTKwave + Win10 by next command:
C:\Program Files\iverilog\bin>iverilog -o fifo.v fifo_tb.v
The compiler gives me the next message:
fifo_tb.v:138:error: Unknown module type:syn_fifo
2 error(s) during elaboration.
These modules were missing:syn_fifo referenced 1 times
At the necessary line "138" maybe the main mistake is covered by the "Number sign" in module instantiation?
/*132|*/ initial begin
/*133|*/ $dumpfile("test.vcd");
/*134|*/ $dumpvars(0,fifo_tb);
/*135|*/ end
/*136|*/
/*137|*/ syn_fifo #(.DATA_WIDTH(DATA_WIDTH),
/*138|*/ .DATA_DEPTH(DATA_DEPTH)) dut ( .clk(clk),
/*139|*/ .rst(rst),
/*140|*/ .din(din),
/*141|*/ .wren(wren),
/*142|*/ .full(full),
/*143|*/ .dout(dout),
/*144|*/ .rden(rden),
/*145|*/ .empty(empty));
/*146|*/
/*147|*/ endmodule
I'm not shure of that.
Seems like you are indicating fifo.v to be your output file, try:
iverilog -o syn_fifo.tb -s fifo_tb fifo_tb.v fifo.v
-o -> output file
-s -> top module (in this case, the test one)
(after everything, include all the files)
Then, to run it:
vvp syn_fifo.tb
Thank you, dear #m4j0rt0m
I just forgot to type in the output file name at the CMD window. Was very exhausted so haven't noticed such a detail)))
Usually it looks like:
iverilog -o OUTPUT_FILE_NAME fifo_tb.v fifo.v
And also I tried your advice, and it's finally done!
Related
this is a very basic question but if somebody can help me with these errors, I'd really appreciate it. I am an EE undergrad, new to Verilog, and I'd appreciate any help/explanation.
The errors I received were:
10028 Can't resolve multiple constant drivers for "led" at compare_block.sv (66)
10029 Constant driver at compare_block.sv(61)
What are the multiple constant drivers here? Originally, I had the led assignment (led <= led_val) within the second always block, and I thought moving it up to the first always block would change the errors, but it did not.
module compare_block (clk, reset_n, result, led);
parameter data_width = 8; /
parameter size = 1000;
input clk, reset_n;
input [data_width:0] result;
logic [(data_width):0] data_from_rom;
logic [9:0] addr_to_rom;
output reg led;
reg [(data_width):0] comp_sig [size-1:0];
reg [data_width:0] comp_sig_temp;
reg [(data_width):0] filt_sig [size-1:0];
reg [(data_width):0] ans_sig [size-1:0];
integer i, iii;
reg [9:0] ii ;
integer sum_array;
wire [(data_width+3):0] array_avg;
reg [data_width:0] summed_arr [size-2 : 0];//container for all summation steps
wire total_sum;
reg ans_sig_done;
reg [data_width : 0] summed_ans;
reg [data_width:0] max_val, error_val;
initial begin
i = 0;
ii = 0;
led=0;
data_from_rom='b000000000;
summed_ans='b000000000;
max_val='b000000000;
for (iii=0;iii<(size-1);iii=iii+1) begin
filt_sig[iii]=0;
ans_sig [iii]=0;
comp_sig[iii]=0;
summed_arr[iii]=0;
end
end
//port map to ROM
rom_compare ref_wave(
.clk(clk),
.addr(addr_to_rom), //text file?
.data(data_from_rom)
);
//Moore FSM
localparam [3:0]
s0=0, s1 = 1, s2 = 2, s3 = 3, s4 = 4, s5 = 5;
reg [3:0] state_reg, state_next;
initial state_next = 0;
always #(posedge clk, negedge reset_n) begin
if (reset_n == 'b0) begin //reset is active low
state_reg <= s0;
end else begin
state_reg <= state_next;
led <= led_val;
end
end
always #(state_reg) begin
state_next = state_reg;
led=0;
case (state_reg)
s0 : begin //initial state, reset state
if (!reset_n) begin
led <= 0;
ii <= 0;
end else begin
state_next <= s1;
end
end
s1 : begin
if (ii>(size)) begin
ii <= 0;
end else begin
addr_to_rom <= ii;
state_next <= s2;
end
end
s2 : begin
comp_sig_temp <= data_from_rom;
filt_sig [ii] <= result;
state_next <= s3;
end
s3 : begin
comp_sig[ii] <= comp_sig_temp;
state_next <= s4;
end
s4 : begin
ans_sig[ii] <= filt_sig[ii] - comp_sig[ii];
state_next <= s5;
end
s5 : begin
if (ii>(size-2)) begin
ans_sig_done = 1;
end else begin
ans_sig_done = 0;
end
ii <= ii+1;
state_next <= s0;
end
endcase
end
reg [(data_width+2):0] sum;
integer j;
always #* begin
sum = 0;
if (ans_sig_done == 1) begin
for (j=4; j<(size-1); j=j+2) begin
sum = sum +ans_sig[j];
if (ans_sig[j] > max_val) begin
max_val = ans_sig[j];
end
end
end
end
assign array_avg = sum >> 'd3; //2^3 = 8
always #(clk, result) begin //posedge clk, result
filt_sig [i] <= result;
i <= i + 1;
end
assign error_val = max_val >> 'd2; //approx 25% of max value of array
reg led_val;
always #(*)
begin
if (array_avg < error_val) begin
led_val <= 'b1;
end else begin
led_val <= 'b0;
end
end
endmodule
I figured it out!
The two instances were me trying to initialize one led = 0 in one always block and then assigning led <= led_val in another. You can't refer to an output in two different always blocks.
i wrote a fifo in system verilog
i try to push some data to this fifo (i wrote a tb) and when i push data the fifo_wr_ptr, fifo_fre_space,fifo_used_space don't update (only data write to mem[0])
i will be glad for help (why my ptr don't increment by 1 for example)
Thanks alot!
and here is my simulation that shows my problem:
i attached my code:
module fifo
#(parameter WIDTH = 32, parameter DEPTH = 64 ) ( clk, rst_l, sw_rst, fifo_din, fifo_push_en, fifo_pop_en, fifo_dout, fifo_o_full, fifo_o_empty, fifo_used_space, fifo_free_space );
function integer log2; //can use the $clog2() function
input [31:0] value;
reg [31:0] value_tmp;
begin value_tmp = value; for(log2=0; value_tmp>0; log2=log2+1)
value_tmp=(value_tmp>>1);
end endfunction
localparam DEPTH_LOG2 = log2(DEPTH);
//interface input clk; input rst_l; input sw_rst; input[WIDTH-1:0] fifo_din; input fifo_push_en; input fifo_pop_en; output logic[WIDTH-1:0] fifo_dout; output logic fifo_o_full; output logic fifo_o_empty; output logic[DEPTH_LOG2-1:0] fifo_used_space; output logic[DEPTH_LOG2-1:0] fifo_free_space; logic debug_flag; //internal logic logic[WIDTH-1:0] mem[DEPTH_LOG2-1:0]; logic[DEPTH_LOG2-1:0] fifo_rd_ptr,fifo_wr_ptr;
assign fifo_o_empty = (fifo_used_space==0); assign fifo_o_full = (fifo_free_space==0);
always # (posedge clk or negedge rst_l) begin if(~rst_l) begin
fifo_free_space <= DEPTH;
fifo_used_space <= 0;
fifo_rd_ptr <= 0;
fifo_wr_ptr <= 0;
debug_flag <=0 ;
end else if (~sw_rst) begin
fifo_free_space <= DEPTH;
fifo_used_space <= 0;
fifo_rd_ptr <= 0;
fifo_wr_ptr <= 0;
debug_flag <= 0;
end else if(fifo_push_en==1 && fifo_o_full==0 && fifo_pop_en==0) begin //the fifo isn't full and can perform the write trasaction (and no read transaction)
fifo_used_space <= fifo_used_space + 1;
fifo_free_space <= fifo_free_space - 1;
mem[fifo_wr_ptr]<= fifo_din;
debug_flag <= 1;
if(fifo_wr_ptr == (DEPTH - 1))
fifo_wr_ptr <= 0;
else
fifo_wr_ptr++;
end else if (fifo_pop_en==1 && fifo_o_empty==0 && fifo_push_en==0) begin // the fifo isn't empty and can perform the read trasaction (and no write trasaction)
fifo_used_space <= fifo_used_space - 1;
fifo_free_space <= fifo_free_space + 1;
fifo_dout <= mem[fifo_rd_ptr];
if(fifo_rd_ptr == (DEPTH - 1)) begin
fifo_rd_ptr <= 0;
end else begin
fifo_rd_ptr <= fifo_rd_ptr + 1;
end end else begin
fifo_rd_ptr <= fifo_rd_ptr;
//fifo_wr_ptr <= fifo_wr_ptr;
//fifo_dout <= fifo_dout;
//fifo_used_space <= fifo_used_space;
fifo_free_space <= fifo_free_space; end end
endmodule
and here is the tb code:
`define WIDTH 32
`define DEPTH 64
module fifo_tb();
function integer log2; //can use the $clog2() function
input [31:0] value;
reg [31:0] value_tmp;
begin
value_tmp = value;
for(log2=0; value_tmp>0; log2=log2+1)
value_tmp=(value_tmp>>1);
end
endfunction
localparam DEPTH_LOG2 = log2(`DEPTH);
logic clk,rst_l,sw_rst,fifo_push_en,fifo_pop_en,fifo_o_full,fifo_o_empty;
logic[`WIDTH-1:0] fifo_din,fifo_dout,tempdata;
logic[DEPTH_LOG2-1:0] fifo_used_space,fifo_free_space;
fifo #(`WIDTH,`DEPTH) ff(.clk(clk), .rst_l(rst_l), .sw_rst(sw_rst), .fifo_din(fifo_din),
.fifo_push_en(fifo_push_en), .fifo_pop_en(fifo_pop_en),
.fifo_dout(fifo_dout), .fifo_o_full(fifo_o_full), .fifo_o_empty(fifo_o_empty),
.fifo_used_space(fifo_used_space), .fifo_free_space(fifo_free_space) );
initial
begin
clk =0;
rst_l = 0;
sw_rst= 0;
fifo_push_en=0;
fifo_pop_en=0;
fifo_din=0;
tempdata=0;
#15 rst_l=1;
#1 sw_rst=1;
push(10);
push(20);
push(30);
push(40);
pop(tempdata);
push(tempdata);
end
always
#5 clk=~clk;
task push;
input[`WIDTH-1:0] data;
if(fifo_o_full)
$display("--- Cannot push: Buffer full ----");
else begin
$display("Pushed: ",data);
#(posedge clk);
fifo_din = data;
fifo_push_en=1;
#(posedge clk);
fifo_push_en=0;
end
endtask
task pop;
output [`WIDTH-1:0] data;
if(fifo_o_empty)
$display("Cannot pop: buffer empty ---");
else begin
#(posedge clk);
fifo_pop_en=1;
#(posedge clk);
fifo_pop_en=0;
data=fifo_dout;
$display("----- Poped : ",data);
end
endtask
endmodule
Taking aside the oddity related to pointer incrementation, the code itself is confusing and difficult to deal with. Pasting reference FIFO module that should do the job, this also should help you to grasp on basics of coding style.
//----------------------------------------------------
// Module Name: fifo_sync.v
//----------------------------------------------------
// Description: generic sync FIFO module
//----------------------------------------------------
module fifo_sync #
(
parameter FIFO_DATA_WIDTH = 'd32,
parameter FIFO_PTR_WIDTH = 'd6
)
(
//------------------------------------------------
// Inputs
//------------------------------------------------
input clk,
input rst_n,
input wr_en,
input [FIFO_DATA_WIDTH-1:0] wr_data,
input rd_en,
//------------------------------------------------
// Outputs
//------------------------------------------------
output reg [FIFO_DATA_WIDTH-1:0] rd_data,
output stat_full,
output stat_empty,
output [ FIFO_PTR_WIDTH-1:0] stat_occupancy
);
//------------------------------------------------
// Local Parameters
//------------------------------------------------
localparam FIFO_DEPTH = 2**(FIFO_PTR_WIDTH-1);
//------------------------------------------------
// Internal Register(s)/Wire(s)/Integer(s)
//------------------------------------------------
reg [ FIFO_PTR_WIDTH-1:0] wr_ptr;
reg [ FIFO_PTR_WIDTH-1:0] rd_ptr;
reg [FIFO_DATA_WIDTH-1:0] fifo_array [FIFO_DEPTH-1:0];
integer int_i;
//------------------------------------------------
// Write Pointer Logic
//------------------------------------------------
always #(posedge clk or negedge rst_n)
begin: p_wr_ptr
if (!rst_n)
wr_ptr <= {FIFO_PTR_WIDTH{1'b0}};
else if (wr_en & !stat_full)
wr_ptr <= wr_ptr + 1'b1;
end
//------------------------------------------------
// Read Pointer Logic
//------------------------------------------------
always #(posedge clk or negedge rst_n)
begin: p_rd_ptr
if (!rst_n)
rd_ptr <= {FIFO_PTR_WIDTH{1'b0}};
else if (rd_en & !stat_empty)
rd_ptr <= rd_ptr + 1'b1;
end
//------------------------------------------------
// Status Interface
//------------------------------------------------
// FIFO full status flag
assign stat_full = (wr_ptr[FIFO_PTR_WIDTH-1] ^ rd_ptr[FIFO_PTR_WIDTH-1]) & (wr_ptr[FIFO_PTR_WIDTH-2:0] == rd_ptr[FIFO_PTR_WIDTH-2:0]);
// FIFO empty status flag
assign stat_empty = (wr_ptr == rd_ptr);
// FIFO occupancy status
assign stat_occupancy = wr_ptr - rd_ptr;
//-----------------------------------------------
// FIFO Write
//-----------------------------------------------
always #(posedge clk or negedge rst_n)
begin: p_fifo_write
if (!rst_n)
for (int_i = 0; int_i < FIFO_DEPTH - 1; int_i = int_i + 1)
fifo_array[int_i] <= {FIFO_DATA_WIDTH{1'b0}};
else if (wr_en & !stat_full)
fifo_array[wr_ptr] <= wr_data;
end
//-----------------------------------------------
// FIFO Read
//-----------------------------------------------
always #(posedge clk or negedge rst_n)
begin: p_fifo_read
if (!rst_n)
rd_data <= {FIFO_DATA_WIDTH{1'b0}};
else if (rd_en & !stat_empty)
rd_data <= fifo_array[rd_ptr];
end
endmodule
I am trying to learn valid/ready handshake in verilog. In particular, I am interested to use ready as a flag that indicates the successful transaction of data (i.e., ready_in becomes high after valid_out goes high). I would like to explain my problem using a very simple Verilog example. I have written a convolutional encoder (code below)
module Conv_Encoder_Core(
input wire clk,
input wire reset,
input wire in_bit,
output reg out_A,
output reg out_B,
input wire sleep,
input wire valid_in,
input wire ready_in,
output reg valid_out,
output reg ready_out);
reg [5:0] S;
wire S_A, S_B, clkON;
assign S_A = S[1] ^ S[2] ^ S[4] ^S[5];
assign S_B = S[0] ^ S[1] ^ S[2] ^S[5];
assign clkON = clk & !sleep;
always #(posedge clkON)begin
if (reset) begin
S <=0;
valid_out <=0;
ready_out <=0;
end else if (valid_in) begin
out_A <= in_bit ^ S_A;
out_B <= in_bit ^ S_B;
valid_out <=1;
if (ready_in)begin
S<= S<<1;
S[0] <=in_bit;
ready_out <=1;
end else begin
ready_out <=0;
end
end else begin
valid_out <=0;
ready_out <=0;
end
end
endmodule
I am interested to use ready_in flag as an indicator that data out_A and out_B are received by the next block, so my block can accept the new data by setting ready_out flag high. I have written a testbench for this block, however, I am not getting the results I am expecting
`timescale 1 ns/1 ns
module TB_Conv();
reg clk;
//---------------clock generator-----------------------
initial begin
clk = 1'b0;
#5;
clk = 1'b1;
forever begin
#5 clk = ~clk;
end
end
//------------------ dump -----------------------
initial begin
$dumpfile("dumpVCD.vcd");
$dumpvars(10);
end
localparam N_DATA=10;
reg in_bits_vec [0:N_DATA-1];
initial begin
in_bits_vec[0] = 1'b1;
in_bits_vec[1] = 1'b0;
in_bits_vec[2] = 1'b0;
in_bits_vec[3] = 1'b0;
in_bits_vec[4] = 1'b0;
in_bits_vec[5] = 1'b0;
in_bits_vec[6] = 1'b0;
in_bits_vec[7] = 1'b0;
in_bits_vec[8] = 1'b0;
in_bits_vec[9] = 1'b1;
end
reg in_bit, ready_in,reset, valid_in;
Conv_Encoder_Core UUT(.clk(clk),
.reset(reset),
.in_bit(in_bit),
.out_A(out_A),
.out_B(out_B),
.sleep(1'b0),
.valid_in(valid_in),
.ready_in(ready_in),
.valid_out(valid_out),
.ready_out(ready_out));
//---------------- code starts here -------------------//
reg [3:0] addr;
always #(posedge clk) begin
if (reset)begin
addr<=0;
valid_in <=0;
in_bit <=0;
end else if (addr < 10) begin
in_bit <= in_bits_vec[addr];
valid_in <=1'b1;
if (ready_out) begin
addr <= addr+1'b1;
end
end else begin
in_bit <=0;
valid_in <=0;
end
if (valid_out==1) ready_in <= 1;
else ready_in <= 0;
end
// ----------- reset logic -----------//
reg [3:0] cnt;
initial cnt=0;
always #(negedge clk)begin
if (cnt<5) begin
reset = 1;
cnt=cnt+1;
end else reset =0;
end
initial begin
#1000;
$finish;
end
endmodule
if you look at the input data (in the testbech), you can see it is 1000000000. I am expecting to see 1 being passed through S register as follows:
S = 000000 //at beginning
S = 000001 // after ready_out=1
S = 000010
S = 000100
however, the results I get is entirely different(please see snapshot).
Another problem I have is that inbit=1 continues two clock cycles more than what I expect. in fact when ready_out=1, I expect to see that in_bit becomes zero but this happens two clock cycles later(yellow cursor in the snapshot ).
I would be most grateful if someone could explain what I do wrong in this example.
Conv_Encoder_Core
module Conv_Encoder_Core
(
input wire clk,
input wire reset,
input wire in_bit,
output reg out_A,
output reg out_B,
input wire sleep,
// input channel
input wire inp_valid_i,
output wire inp_ready_o,
// output channel
output reg out_valid_o,
input reg out_ready_i
);
reg [5:0] S;
wire S_A, S_B, clkON;
assign S_A = S[1] ^ S[2] ^ S[4] ^S[5];
assign S_B = S[0] ^ S[1] ^ S[2] ^S[5];
assign clkON = clk & !sleep;
// -- Changes start here -- //
wire wr_en;
reg full_r;
assign wr_en = ~full_r | out_ready_i;
always #(posedge clkON)begin
if (reset) begin
S <=0;
full_r <=0;
end else begin
if (wr_en) begin
if (inp_valid_i) begin
full_r <= 1;
out_A <= in_bit ^ S_A;
out_B <= in_bit ^ S_B;
S <= S<<1;
S[0] <=in_bit;
end else begin
full_r <= 0;
end
end
end
end
assign inp_ready_o = wr_en;
assign out_valid_o = full_r;
endmodule
tb
`timescale 1 ns/1 ns
module tb();
reg clk;
//---------------clock generator-----------------------
initial begin
clk = 1'b0;
#5;
clk = 1'b1;
forever begin
#5 clk = ~clk;
end
end
//------------------ dump -----------------------
initial begin
$dumpfile("dumpVCD.vcd");
$dumpvars(10);
end
localparam N_DATA=10;
reg in_bits_vec [0:N_DATA-1];
initial begin
in_bits_vec[0] = 1'b1;
in_bits_vec[1] = 1'b0;
in_bits_vec[2] = 1'b0;
in_bits_vec[3] = 1'b0;
in_bits_vec[4] = 1'b0;
in_bits_vec[5] = 1'b0;
in_bits_vec[6] = 1'b0;
in_bits_vec[7] = 1'b0;
in_bits_vec[8] = 1'b0;
in_bits_vec[9] = 1'b1;
end
reg in_bit, reset, inp_valid, inp_ready, out_valid, out_ready;
Conv_Encoder_Core UUT(.clk(clk),
.reset(reset),
.in_bit(in_bit),
.out_A(out_A),
.out_B(out_B),
.sleep(1'b0),
// input channel
.inp_valid_i(inp_valid),
.inp_ready_o(inp_ready),
// output channel
.out_valid_o(out_valid),
.out_ready_i(out_ready));
//---------------- code starts here -------------------//
reg [3:0] addr;
// -- Transmitter Side -- //
always #(posedge clk) begin: ff_addr
if (reset)begin
addr <= 0;
end else begin
if (addr < 10) begin
if (inp_valid && inp_ready) begin
addr <= addr + 1;
end
end else begin
addr <= 0;
end
end
end
assign inp_valid = (addr < 10) ? 1'b1 : 1'b0;
assign in_bit = in_bits_vec[addr];
// -- Receiver Side -- //
always #(posedge clk) begin: ff_ready_in
if (reset) begin
out_ready <= 0;
end else begin
out_ready <= $urandom_range(0, 1); // some randomness on the receiver, otherwise, we won't see if our DUT behaves correctly in case of ready=0
end
end
// ----------- reset logic -----------//
reg [3:0] cnt;
initial cnt=0;
always #(negedge clk)begin
if (cnt<5) begin
reset = 1;
cnt=cnt+1;
end else reset =0;
end
initial begin
#1000;
$finish;
end
endmodule
Issues with your implementation
Bad protocol definition & implementation
You are defining a protocol that looks more like "request/acknowledge" than "ready/valid" one, because data transmissions in your protocol are acknowledged after a one-cycle delay. What you need is concurrent transmission acknowledge in the same cycle, something like the following:
A valid data transmission is indicated by the Transmitter through valid=1 and are acknowledged by the Receiver through ready=1. So, a data transmission is valid only when valid && ready in the same cycle. Note that input data is equivalent to in_bit in your case, while output data is out_A and out_B.
Input/Output ready/valid channel confusion
If you add a processing/buffering unit between the Transmitter and the Receiver of the above channel, then what you got is something like this:
In that case, your buffer is the Conv_Encoder_Core module and, apart from its internal core logic, it must expose an input ready/valid channel, from which it receives input data, and an output one, from which it outputs its data. Also note that the Transmitter and the Receiver, are implemented by the testbench code (tb module). See
"Transmitter Side" and "Receiver Side" comments in code.
I want to implement in Verilog the following Matlab code:
symBuf = [symBuf(numFFT/2+1:end); zeros(numFFT/2,1)];
symBuf(KF+(1:KF)) = symBuf(KF+(1:KF)) + txSymb;
It is a simple overlap and add operation.
Here is my implementation:
module overlap
#(K = 3,
FFT = 128
)
(
input signed [15:0] symbInReal ,
input signed [15:0] symbInImag ,
input clock ,
input reset ,
input readyIn ,
input validIn ,
input lastIn ,
output signed [15:0] outReal ,
output signed [15:0] outImag ,
output reg lastOut ,
output wire readyOut ,
output reg validOut
);
reg signed [15:0] previousSymbolReal [2*FFT*K-1:0] ;
reg signed [15:0] previousSymbolImag [2*FFT*K-1:0] ;
reg signed [15:0] txSymbolBuffReal [K*FFT-1:0] ;
reg signed [15:0] txSymbolBuffImag [K*FFT-1:0] ;
reg [15:0] counter ;
reg [1:0] state ;
reg [3:0] nextstate ;
reg [15:0] clockcount ;
reg signed [15:0] outputValueReal ;
reg signed [15:0] outputValueImag ;
reg [15:0] buffcount ;
reg [7:0] symboutcount ;
reg [7:0] symbincount ;
reg last ;
reg lastvalidout ;
wire lastout ;
integer i;
initial begin
for (i=0; i<2*FFT*K ; i = i + 1) begin
previousSymbolReal[i] = 0;
previousSymbolImag[i] = 0;
end
end
always#(posedge clock) begin
if(~reset) begin
counter <= 0;
end else begin
counter <= counter +1;
if(nextstate != state)
counter <= 0;
end
end
always#(*) begin
if(~reset) begin
nextstate = 0;
end else begin
nextstate = state;
if(readyIn) begin
case(state)
4'd0: begin
if(validIn || last) begin
nextstate = 1;
end
end
4'd1: begin
if (counter == (FFT*K-2)) begin
nextstate = 2;
end
end
4'd2: begin
nextstate = 0;
end
endcase
end
end
end
always#(posedge clock) begin
if(~reset) begin
state <= 0;
end else begin
if(readyIn)
state <= nextstate;
end
end
always#(posedge clock) begin
if(~reset) begin
clockcount <= 0;
symboutcount <= 0;
lastOut <= 0;
end else begin
if(readyIn) begin
clockcount <= clockcount +1 ;
case(state)
4'd0: begin
validOut <= 0;
clockcount <= 0;
lastOut <= 0;
end
4'd1: begin
if(~lastvalidout)
validOut <= 1;
outputValueReal <= previousSymbolReal[clockcount+ FFT/2];
outputValueImag <= previousSymbolImag[clockcount+ FFT/2];
end
4'd2: begin
outputValueReal <= previousSymbolReal[clockcount + FFT/2];
outputValueImag <= previousSymbolImag[clockcount + FFT/2];
clockcount <= 0;
if(~lastvalidout)
validOut <= 1;
if(symboutcount == symbincount + 1 && last)
lastOut <= 1;
symboutcount <= symboutcount +1 ;
end
endcase
end
end
end
assign readyOut = readyIn;
genvar M;
generate
for(M=0;M<K*FFT;M=M+1) begin
always#(posedge clock) begin
if(state==2) begin
previousSymbolReal[M] <= previousSymbolReal[M+FFT/2];
previousSymbolImag[M] <= previousSymbolImag[M+FFT/2];
end
end
end
for(M=K*FFT;M<2*K*FFT-FFT/2;M=M+1) begin
always#(posedge clock) begin
if(state==2) begin
previousSymbolReal[M] <= previousSymbolReal[M+FFT/2]+txSymbolBuffReal[M-K*FFT];
previousSymbolImag[M] <= previousSymbolImag[M+FFT/2]+txSymbolBuffImag[M-K*FFT];
end
end
end
for(M=2*K*FFT-FFT/2;M<2*K*FFT;M=M+1) begin
always#(posedge clock) begin
if(state==2) begin
previousSymbolReal[M] <= txSymbolBuffReal[M-K*FFT];
previousSymbolImag[M] <= txSymbolBuffImag[M-K*FFT];
end
end
end
endgenerate
always#(posedge clock) begin
if(~reset) begin
buffcount <= 0;
symbincount <= 0;
last <= 0;
end else begin
if(validIn) begin
txSymbolBuffReal[buffcount] <= symbInReal;
txSymbolBuffImag[buffcount] <= symbInImag;
buffcount <= buffcount +1;
if(buffcount == K*FFT-1) begin
symbincount <= symbincount + 1;
buffcount <= 0;
end
if(lastIn)
last <= 1;
end
end
end
always#(posedge clock) begin
if(~reset)
lastvalidout <= 0;
else begin
if(last && lastOut)
lastvalidout <= 1;
end
end
assign outReal = outputValueReal;
assign outImag = outputValueImag;
endmodule
The problem here is that I have 4 huge arrays which take up to 4 times what is available in my FPGA.
Hence, I want to be able to use block RAMs. However, I don't think it's possible due to the number of read and write operations performed.
Does anyone have a solution for this?
However, I don't think it's possible due to the number of read and write operations performed.
Correct. At least, not without major changes to your design.
A typical block RAM element can only read or write one (or sometimes two) values per clock cycle, but your generate loops are trying to update every element in the RAM at once!
To make this operation use a block RAM, you will need to implement a state machine to update one element per clock cycle, and to sequence operations such that other states wait until the updates have completed.
If you want to accelerate this, you may be able to split the array into multiple block RAMs so that multiple values can be updated in parallel. (You will need to carefully consider which elements need to be read/written to avoid conflicts.)
I have a program written in Verilog and I want to convert it into a FSM automatically. Is this possible (just to visualize it)?
Here is the code :
module pci(reset,clk,frame,irdy,trdy,devsel,idsel,ad,cbe,par,stop,inta,led_out);
input reset;
input clk;
input frame;
input irdy;
output trdy;
output devsel;
input idsel;
inout [31:0] ad;
input [3:0] cbe;
inout par;
output stop;
output inta;
output [3:0] led_out;
parameter DEVICE_ID = 16'h9500;
parameter VENDOR_ID = 16'h106d; // Sequent!
parameter DEVICE_CLASS = 24'hFF0000; // Misc
parameter DEVICE_REV = 8'h01;
parameter SUBSYSTEM_ID = 16'h0001; // Card identifier
parameter SUBSYSTEM_VENDOR_ID = 16'hBEBE; // Card identifier
parameter DEVSEL_TIMING = 2'b00; // Fast!
reg [2:0] state;
reg [31:0] data;
reg [1:0] enable;
parameter EN_NONE = 0;
parameter EN_RD = 1;
parameter EN_WR = 2;
parameter EN_TR = 3;
reg memen; // respond to baseaddr?
reg [7:0] baseaddr;
reg [5:0] address;
parameter ST_IDLE = 3'b000;
parameter ST_BUSY = 3'b010;
parameter ST_MEMREAD = 3'b100;
parameter ST_MEMWRITE = 3'b101;
parameter ST_CFGREAD = 3'b110;
parameter ST_CFGWRITE = 3'b111;
parameter MEMREAD = 4'b0110;
parameter MEMWRITE = 4'b0111;
parameter CFGREAD = 4'b1010;
parameter CFGWRITE = 4'b1011;
`define LED
`ifdef LED
reg [3:0] led;
`endif
`undef STATE_DEBUG_LED
`ifdef STATE_DEBUG_LED
assign led_out = ~state;
`else
`ifdef LED
assign led_out = ~led; // board is wired for active low LEDs
`endif
`endif
assign ad = (enable == EN_RD) ? data : 32'bZ;
assign trdy = (enable == EN_NONE) ? 'bZ : (enable == EN_TR ? 1 : 0);
assign par = (enable == EN_RD) ? 0 : 'bZ;
reg devsel;
assign stop = 1'bZ;
assign inta = 1'bZ;
wire cfg_hit = ((cbe == CFGREAD || cbe == CFGWRITE) && idsel && ad[1:0] == 2'b00);
wire addr_hit = ((cbe == MEMREAD || cbe == MEMWRITE) && memen && ad[31:12] == {12'b0, baseaddr});
wire hit = cfg_hit | addr_hit;
always #(posedge clk)
begin
if (~reset) begin
state <= ST_IDLE;
enable <= EN_NONE;
baseaddr <= 0;
devsel <= 'bZ;
memen <= 0;
`ifdef LED
led <= 0;
`endif
end
else begin
case (state)
ST_IDLE: begin
enable <= EN_NONE;
devsel <= 'bZ;
if (~frame) begin
address <= ad[7:2];
if (hit) begin
state <= {1'b1, cbe[3], cbe[0]};
devsel <= 0;
// pipeline the write enable
if (cbe[0])
enable <= EN_WR;
end
else begin
state <= ST_BUSY;
enable <= EN_NONE;
end
end
end
ST_BUSY: begin
devsel <= 'bZ;
enable <= EN_NONE;
if (frame)
state <= ST_IDLE;
end
ST_CFGREAD: begin
enable <= EN_RD;
if (~irdy || trdy) begin
case (address)
0: data <= { DEVICE_ID, VENDOR_ID };
1: data <= { 5'b0, DEVSEL_TIMING, 9'b0, 14'b0, memen, 1'b0};
2: data <= { DEVICE_CLASS, DEVICE_REV };
4: data <= { 12'b0, baseaddr, 8'b0, 4'b0010 }; // baseaddr + request mem < 1Mbyte
11: data <= {SUBSYSTEM_ID, SUBSYSTEM_VENDOR_ID };
16: data <= { 24'b0, baseaddr };
default: data <= 'h00000000;
endcase
address <= address + 1;
end
if (frame && ~irdy && ~trdy) begin
devsel <= 1;
state <= ST_IDLE;
enable <= EN_TR;
end
end
ST_CFGWRITE: begin
enable <= EN_WR;
if (~irdy) begin
case (address)
4: baseaddr <= ad[19:12]; // XXX examine cbe
1: memen <= ad[1];
default: ;
endcase
address <= address + 1;
if (frame) begin
devsel <= 1;
state <= ST_IDLE;
enable <= EN_TR;
end
end
end
ST_MEMREAD: begin
enable <= EN_RD;
if (~irdy || trdy) begin
case (address)
`ifdef LED
0: data <= { 28'b0, led };
`endif
default: data <= 'h00000000;
endcase
address <= address + 1;
end
if (frame && ~irdy && ~trdy) begin
devsel <= 1;
state <= ST_IDLE;
enable <= EN_TR;
end
end
ST_MEMWRITE: begin
enable <= EN_WR;
if (~irdy) begin
case (address)
`ifdef LED
0: led <= ad[3:0];
`endif
default: ;
endcase
address <= address + 1;
if (frame) begin
devsel <= 1;
state <= ST_IDLE;
enable <= EN_TR;
end
end
end
endcase
end
end
endmodule
If there is no automatic way, could you explain a way of doing this?
Here is an FSM made with hand but can't test so ...
Does it seem ok?
It is sometimes easier to write the code and have the documentation generated from that. Sometimes you inherit legacy code without documentation, in these situations especially if new to a language tools to help visualise what is happening can be quite useful.
With cadence tools you can run your code with 'code coverage' then imc can load the coverage data and run FSM Analysis.
I have included a simple FSM below and show the generated state diagram.
module simple_fsm();
//Inputs to FSM
logic clk;
logic rst_n;
logic [1:0] state ;
logic [1:0] nextstate;
logic turn_on ;
logic turn_off ;
localparam S_OFF = 2'b00;
localparam S_GO_ON = 2'b01;
localparam S_ON = 2'b10;
localparam S_GO_OFF = 2'b11;
// State FlipFlop
always #(posedge clk or negedge rst_n) begin
if (~rst_n) begin
state <= 2'b0;
end
else begin
state <= nextstate;
end
end
//Nextstate Logic
always #* begin
case (state)
2'd0 : if (turn_on) begin
nextstate = S_GO_ON;
end
2'd1 : nextstate = S_ON;
2'd2 : if (turn_off) begin
nextstate = S_GO_OFF ;
end
2'd3 : nextstate = S_OFF;
endcase
end
//TB clk
initial begin
#1ns;
clk = 0;
forever begin
#20ns;
clk = ~clk;
end
end
//The Test
initial begin
rst_n = 1'b0;
turn_on = 1'b0;
turn_off = 1'b0;
#(posedge clk);
#(posedge clk);
rst_n = 1'b1 ;
#(posedge clk);
turn_on = 1'b1;
#(posedge clk);
turn_on = 1'b0;
#(posedge clk);
#(posedge clk);
#100ms;
$finish();
end
endmodule
Execute with :
$ irun simple_fsm.sv -coverage all -covdut simple_fsm
$ imc &
Load cov_work (folder created by above simulation) in imc, select simple_fsm and choose FSM Analysis.
imc also helps to visualise your test coverage as well. Arcs and states that have not been hit are shown in red.
We have seen that there are some tools which can visualise the FSM, another part of the question is; is the syntax of the purposed FSM suitable for these tools.
#vermaete has reported that Modelsim SE can not see the FSM. From imc I get :
Which does not seem to cover the complexity of the code, and is shown as only having 2 reachable states, IDLE and BUSY. I would recommend if OP is going down the route of using tools to visualise, adopt a simpler (syntax) FSM structure so that the tools can parse it better.
The better and expensive simulators can detect FSM's in the code and make a visualization of it. E.g. the Modelsim SE version. These can be nice to understand code and check the coveage.
But making you're own drawing of a 6-state FSM is not that hard.
The way to check if it's OK is to write a simulation and check that the behaviour is what you want. There is no point getting a bubble diagram out and seeing if it matches your hand-drawn one, as you have no way of knowing if your hand-drawn diagram is correct...
case(segmentRead)
//-------------------
SEGMENT0: begin
READ_Ready_EEPROM <= 1'b0;
READ_RDSR_Enable <= 1'b0;
Read_Enable <= 1'b0;
READ_RDSR_DATA_REG <= 8'b0;
// READ_DATA_REG <= 8'b0;
end
//-------------------
SEGMENT2: begin
READ_RDSR_Enable <= 1'b1;
READ_RDSR_DATA_REG <= 8'b0;
end
// //-------------------
SEGMENT3: begin
READ_RDSR_Enable <= 1'b0;
READ_RDSR_DATA_REG <= RDSR_Data;
end
//-------------------
SEGMENT4: begin
Read_Enable <= 1'b1;
end
//-------------------
SEGMENT5: begin
Read_Enable <= 1'b0;
READ_DATA_REG <= Read_Data;
end
//-------------------
SEGMENT6: begin
READ_Ready_EEPROM <= 1'b1;
end
//-------------------
endcase