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Honored ContributorPCI testbench verifying....please help...
Guys,
I have created myself a PCI testbench for verifying home made PCI card, Can anyone give idea if I'm doing in a right way or not ? I'm following the paper "Interfacing PCI with FPGA" The port is not yet completed, because it's a test..... Any ideas or references will be very appreciated, Thanks a lot in advance. Please see the code :
/* testbench for PCI
File: PCI_testbench.v */
//`timescale 10ns / 10ns
module pci_testbench;
wire t_ad; //input output data multiplex with address
reg t_cbe; //command or byte enable
reg t_frame; //input
reg t_clk; //input
reg t_ad_value;
reg t_irdy; //input
reg t_devsel; //output
reg t_trdy; //output
reg t_reset; //input
pci my_pci(.ad(t_ad), .cbe(t_cbe), .clk(t_clk), .frame(t_frame), .irdy(t_irdy), .reset(t_reset));
assign t_ad = t_ad_value;
initial
t_clk = 1'b0 ;
always
# 5 t_clk =~t_clk;
initial
begin
/*
Cycle 1 - The bus is idle
*/
/*
Cycle 2 - The initiator assets a valid address and places a read command on CBE
==>Address phase
*/
# 1 t_reset = 1'b0; //put reset on low
# 1 t_frame = 1'b0; //active low, the device is ready to perform
//#10 t_ad = 32'b1010100010;
# 1 t_cbe = 4'b0010; //read command
# 2 t_ad_value = 32'h0000_0001; //insert address
/*
Cycle 3 ->
The initiator tristates the address, prepare for reading data.
Drive a valid byte enable information on CBE.
Asserts IRDY ==> LOW , indicating it's ready to capture read data.
Asserts DEVSEL ==> LOW, in this cycle or the next as an acknowledgment it has positively decoded the address
The target drives TRDY==>HIGH indicating it is not yet providing valid read data.
*/
# 1 t_reset = 1'b0; //put reset on low
# 1 t_ad_value = 32'bz; //insert tristate value
//#3 t_cbe = //drive a valid byte enable
# 2 t_irdy = 1'b0;
//t_devsel = 1'b0;
//t_trdy = 1'b1;
/*Cycle 4 ->
Target provides valid data and asserts TRDY ==> LOW indicating to the initiator that data is valid.
TRDY and IRDY now are both LOW during this cycle causing a data transfer to take place.
The initiator captures the data.
This is the first data phase.
*/
//#2 t_trdy = 1'b0;
/*
Cycle 5 - The target deasserts TRDY# high
indicating it needs more time to prepare the next data
transfer.
*/
//#1 t_trdy = 1'b1;
/*
Cycle 6 - The second data phase occurs as both
IRDY# and TRDY# are low. The initiator captures
the data provided by the target.
*/
//#2 t_trdy = 1'b0;
/*
Cycle 7 - The target provides valid data for the third
data phase, but the initiator indicates it is not ready
by deasserting IRDY# high.
*/
//#2 t_trdy = 1'b0;
/*
Cycle 8 - The initiator re-asserts IRDY# low to
complete the third data phase. The initiator captures
the data provided by the target. The initiator drives
FRAME# high indicating this is the final data phase
(master termination).
*/
# 1 t_reset = 1'b0; //put reset on low
# 1 t_frame = 1'b1; //final data phase ( master termination)
/*
Cycle 9 - FRAME#, AD, and C/BE# are tri-stated, as
IRDY#, TRDY#, and DEVSEL# are driven inactive
high for one cycle prior to being tri-stated.
*/
# 1 t_reset = 1'b0; //put reset on low
# 1 t_frame = 1'bz; //final data phase ( master termination)
t_ad_value = 32'bz;
t_cbe = 4'bz;
end
endmodule
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 ad;
input cbe;
inout par;
output stop;
output inta;
output 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 state;
reg data;
reg enable;
parameter EN_NONE = 0;
parameter EN_RD = 1;
parameter EN_WR = 2;
parameter EN_TR = 3;
reg memen; // respond to baseaddr?
reg baseaddr;
reg 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 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 == 2'b00);
wire addr_hit = ((cbe == MEMREAD || cbe == MEMWRITE) && memen && ad == {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;
if (hit) begin
state <= {1'b1, cbe, cbe};
devsel <= 0;
// pipeline the write enable
if (cbe)
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; // XXX examine cbe
1: memen <= ad;
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;
`endif
default: ;
endcase
address <= address + 1;
if (frame) begin
devsel <= 1;
state <= ST_IDLE;
enable <= EN_TR;
end
end
end
endcase
end
end
endmodule
