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    /m1_core/trunk/hdl/behav/ps2_keyboard_model
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Rev 36 → Rev 54

/ps2_keyboard_model.v
0,0 → 1,299
//////////////////////////////////////////////////////////////////////
//// ////
//// ps2_keyboard_model.v ////
//// ////
//// This file is part of the "ps2" project ////
//// http://www.opencores.org/cores/ps2/ ////
//// ////
//// Author(s): ////
//// - mihad@opencores.org ////
//// - Miha Dolenc ////
//// ////
//// All additional information is avaliable in the README.txt ////
//// file. ////
//// ////
//// ////
//////////////////////////////////////////////////////////////////////
//// ////
//// Copyright (C) 2000 Miha Dolenc, mihad@opencores.org ////
//// ////
//// This source file may be used and distributed without ////
//// restriction provided that this copyright statement is not ////
//// removed from the file and that any derivative work contains ////
//// the original copyright notice and the associated disclaimer. ////
//// ////
//// This source file is free software; you can redistribute it ////
//// and/or modify it under the terms of the GNU Lesser General ////
//// Public License as published by the Free Software Foundation; ////
//// either version 2.1 of the License, or (at your option) any ////
//// later version. ////
//// ////
//// This source is distributed in the hope that it will be ////
//// useful, but WITHOUT ANY WARRANTY; without even the implied ////
//// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR ////
//// PURPOSE. See the GNU Lesser General Public License for more ////
//// details. ////
//// ////
//// You should have received a copy of the GNU Lesser General ////
//// Public License along with this source; if not, download it ////
//// from http://www.opencores.org/lgpl.shtml ////
//// ////
//////////////////////////////////////////////////////////////////////
//
// CVS Revision History
//
// $Log: not supported by cvs2svn $
// Revision 1.3 2003/10/03 10:16:50 primozs
// support for configurable devider added
//
// Revision 1.2 2002/04/09 13:15:16 mihad
// Wrong acknowledge generation during receiving repaired
//
// Revision 1.1.1.1 2002/02/18 16:16:55 mihad
// Initial project import - working
//
//
 
`include "timescale.v"
 
module ps2_keyboard_model
(
kbd_clk_io,
kbd_data_io,
last_char_received_o,
char_valid_o
);
 
parameter [31:0] kbd_clk_period = 50000; // chould be between 33 and 50 us to generate the clock between 30 and 20 kHz
 
inout kbd_clk_io,
kbd_data_io ;
 
output [7:0] last_char_received_o ;
reg [7:0] last_char_received_o ;
 
output char_valid_o ;
reg char_valid_o ;
 
reg kbd_clk,
kbd_data ;
 
assign kbd_clk_io = kbd_clk ? 1'bz : 1'b0 ;
assign kbd_data_io = kbd_data ? 1'bz : 1'b0 ;
 
reg receiving ;
initial
begin
kbd_clk = 1'b1 ;
kbd_data = 1'b1 ;
 
last_char_received_o = 0 ;
char_valid_o = 0 ;
 
receiving = 0 ;
end
 
always@(kbd_data_io or kbd_clk_io)
begin
// check if host is driving keyboard data low and doesn't drive clock
if ( !kbd_data_io && kbd_data && kbd_clk_io)
begin
// wait for half of clock period
#(kbd_clk_period/2) ;
 
// state hasn't changed - host wishes to send data - go receiving
if ( !kbd_data_io && kbd_data && kbd_clk_io)
kbd_receive_char(last_char_received_o) ;
end
end
 
task kbd_send_char ;
input [7:0] char ;
output transmited_ok ;
output severe_error ;
reg [10:0] tx_reg ;
integer i ;
begin:main
severe_error = 1'b0 ;
transmited_ok = 1'b0 ;
 
wait ( !receiving ) ;
 
tx_reg = { 1'b1, !(^char), char, 1'b0 } ;
 
fork
begin:wait_for_idle
wait( (kbd_clk_io === 1'b1) && (kbd_data_io === 1'b1) ) ;
// disable timeout ;
end
/*begin:timeout
#(256 * kbd_clk_period) ;
$display("Error! Keyboard bus did not go idle in 256 keyboard clock cycles time!") ;
severe_error = 1'b1 ;
transmited_ok = 1'b0 ;
disable main ;
end*/
join
 
#(kbd_clk_period/2) ;
if ( !kbd_clk_io )
begin
transmited_ok = 1'b0 ;
kbd_data = 1'b1 ;
disable main ;
end
 
i = 0 ;
while ( i < 11 )
begin
kbd_data = tx_reg[i] ;
 
#(kbd_clk_period/2) ;
 
if ( !kbd_clk_io )
begin
transmited_ok = 1'b0 ;
kbd_data = 1'b1 ;
disable main ;
end
 
kbd_clk = 1'b0 ;
 
i = i + 1 ;
 
#(kbd_clk_period/2) ;
kbd_clk = 1'b1 ;
end
 
if ( i == 11 )
transmited_ok = 1'b1 ;
end
endtask // kbd_send_char
 
task kbd_receive_char;
output [7:0] char ;
reg parity ;
integer i ;
reg stop_clocking ;
begin:main
i = 0 ;
receiving = 1 ;
stop_clocking = 1'b0 ;
 
#(kbd_clk_period/2) ;
 
while ( !stop_clocking )
begin
 
if ( !kbd_clk_io )
begin
receiving = 0 ;
disable main ;
end
 
kbd_clk = 1'b0 ;
 
#(kbd_clk_period/2) ;
 
kbd_clk = 1'b1 ;
 
if ( i > 0 )
begin
if ( i <= 8 )
char[i - 1] = kbd_data_io ;
else if ( i == 9 )
begin
parity = kbd_data_io ;
if ( parity !== ( !(^char) ) )
$display("Invalid parity bit received") ;
end
end
 
i = i + 1 ;
#(kbd_clk_period/4) ;
if ( i > 9 )
begin
if ( kbd_data_io === 1'b1 )
begin
kbd_data <= 1'b0 ;
stop_clocking = 1'b1 ;
end
end
 
#(kbd_clk_period/4) ;
end
 
kbd_clk = 1'b0 ;
 
#(kbd_clk_period/2) ;
kbd_clk <= 1'b1 ;
kbd_data <= 1'b1 ;
 
receiving = 0 ;
 
if ( i === 10 )
begin
char_valid_o = !char_valid_o ;
end
end
endtask // kbd_receive_char
 
 
time last_clk_low;
time last_clk_diference;
 
 
 
initial
begin
last_clk_low =0;
last_clk_diference =0;
 
end
 
always @(negedge kbd_clk_io)
begin:low_time_check
if (kbd_clk == 1)
begin
last_clk_low =$time;
fork
begin
#61000
$display(" clock low more then 61us");
$display("Time %t", $time) ;
#30000
$display("error clock low more then 90usec");
$display("Time %t", $time) ;
$stop;
end
begin
@(posedge kbd_clk_io);
disable low_time_check;
end
join
end
end
 
 
always @(posedge kbd_clk_io )
begin
if (last_clk_low >0 )
begin
last_clk_diference = $time - last_clk_low;
if (last_clk_diference < 60000)
begin
$display("error time< 60u");
#100 $stop;
end
end
end
 
 
 
 
 
 
endmodule // ps2_keyboard_model
/timescale.v
0,0 → 1,299
`timescale 1ns/1ps

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