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[/] [next186mp3/] [trunk/] [HW/] [timer8253.v] - Blame information for rev 2

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//////////////////////////////////////////////////////////////////////////////////
//
// This file is part of the Next186 Soc PC project
// http://opencores.org/project,next186
//
// Filename: timer8253.v
// Description: Part of the Next186 SoC PC project, timer
//      8253 simplified timer (no gate, only counters 0 and 2, no read back command)
// Version 1.0
// Creation date: May2012
//
// Author: Nicolae Dumitrache 
// e-mail: ndumitrache@opencores.org
//
/////////////////////////////////////////////////////////////////////////////////
// 
// Copyright (C) 2012 Nicolae Dumitrache
// 
// 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 
// 
///////////////////////////////////////////////////////////////////////////////////
// Additional Comments: 
// http://wiki.osdev.org/Programmable_Interval_Timer
//////////////////////////////////////////////////////////////////////////////////
 
`timescale 1ns / 1ps
 
module timer_8253(
    input CS,
         input WR,
    input [1:0]addr,
         input [7:0]din,
         output wire [7:0]dout,
         input CLK_25,
         input clk,             // cpu CLK
         output out0,
         output out2
    );
 
        reg [8:0]rclk = 0; // rclk[8] oscillates at 1193181.8181... Hz
        reg [1:0]cclk = 0;
 
        always @(posedge CLK_25) begin
                if(rclk[7:0] < 8'd208) rclk <= rclk + 21;
                else rclk <= rclk + 57;
        end
 
        always @ (posedge clk) begin
                cclk <= {cclk[0], rclk[8]};
        end
 
        wire a0 = addr == 0;
        wire a2 = addr == 2;
        wire a3 = addr == 3;
        wire cmd0 = a3 && din[7:6] == 0;
        wire cmd2 = a3 && din[7:6] == 2;
        wire [7:0]dout0;
        wire [7:0]dout2;
        wire [7:0]mode0;
        wire [7:0]mode2;
 
        counter counter0 (
                 .CS(CS && (a0 || cmd0)),
                 .WR(WR),
                 .clk(clk),
                 .cmd(cmd0),
                 .din(din),
                 .dout(dout0),
                 .mode(mode0),
                 .CE(cclk)
    );
 
        counter counter2 (
                 .CS(CS && (a2 || cmd2)),
                 .WR(WR),
                 .clk(clk),
                 .cmd(cmd2),
                 .din(din),
                 .dout(dout2),
                 .mode(mode2),
                 .CE(cclk)
                 );
 
        assign out0 = mode0[7];
        assign out2 = mode2[7];
        assign dout =   a0 ? dout0 : dout2;
 
endmodule
 
 
module counter(
         input CS,
    input WR,   // write cmd/data
         input clk,     // CPU clk
    input cmd,
         input [7:0]din,
         output [7:0]dout,
         output reg [7:0]mode,   // mode[7] = output
         input [1:0]CE   // count enable
    );
 
         reg [15:0]count = 0;
         reg [15:0]init = 0;
         reg [1:0]state = 0; // state[1] = init reg filled
         reg strobe = 0;
         reg rd = 0;
         reg latch = 0;
         reg newcmd = 0;
         wire c1 = count == 1;
         wire c2 = count == 2;
         reg CE1 = 0;
 
         assign dout = mode[5] & (~mode[4] | rd) ? count[15:8] : count[7:0];
 
        always @(posedge clk) begin
 
                if(CE == 2'b10) CE1 <= 1;
 
                if(CS) begin
                        if(WR) begin
                                mode[6] <= 1;
                                rd <= 0;
                                latch <= 0;
                                if(cmd) begin   // command
                                        if(|din[5:4]) begin
                                                mode[5:0] <= din[5:0];
                                                newcmd <= 1;
                                                state <= {1'b0, din[5] & ~din[4]};
                                        end else latch <= &mode[5:4];
                                end else begin  // data
                                        state <= state[0] + ^mode[5:4] + 1;
                                        if(state[0]) init[15:8] <= din;
                                        else init[7:0] <= din;
                                end
                        end else begin
                                rd <= ~rd;
                                if(rd) latch <= 0;
                        end
                end else if(state[1] && CE1 && !latch) begin
                        newcmd <= 0;
                        CE1 <= 0;
                        case(mode[3:1])
                                3'b000, 3'b001:
                                        if(mode[6]) begin
                                                mode[7:6] <= 2'b00;
                                                count <= init;
                                        end else begin
                                                count <= count - 1;
                                                if(c1) mode[7] <= 1;
                                        end
                                3'b010, 3'b110: begin
                                        mode[7] <= ~c2;
                                        if(c1 | newcmd) begin
                                                mode[6] <= 1'b0;
                                                count <= init;
                                        end else count <= count - 1;
                                end
                                3'b011, 3'b111: begin
                                        if(c1 | c2 | newcmd) begin
                                                mode[7:6] <= {~mode[7] | newcmd, 1'b0};
                                                count <= {init[15:1], (~mode[7] | newcmd) & init[0]};
                                        end else count <= count - 2;
                                end
                                3'b100, 3'b101:
                                        if(mode[6]) begin
                                                mode[7:6] <= 2'b10;
                                                count <= init;
                                                strobe <= 1;
                                        end else begin
                                                count <= count - 1;
                                                if(c1) begin
                                                        if(strobe) mode[7] <= 0;
                                                        strobe <= 0;
                                                end else mode[7] <= 1;
                                        end
                        endcase
                end
        end
 
endmodule

Line No.	Rev	Author	Line
1	2	ndumitrach	`//////////////////////////////////////////////////////////////////////////////////`
2			`//`
3			`// This file is part of the Next186 Soc PC project`
4			`// http://opencores.org/project,next186`
5			`//`
6			`// Filename: timer8253.v`
7			`// Description: Part of the Next186 SoC PC project, timer`
8			`// 8253 simplified timer (no gate, only counters 0 and 2, no read back command)`
9			`// Version 1.0`
10			`// Creation date: May2012`
11			`//`
12			`// Author: Nicolae Dumitrache`
13			`// e-mail: ndumitrache@opencores.org`
14			`//`
15			`/////////////////////////////////////////////////////////////////////////////////`
16			`//`
17			`// Copyright (C) 2012 Nicolae Dumitrache`
18			`//`
19			`// This source file may be used and distributed without`
20			`// restriction provided that this copyright statement is not`
21			`// removed from the file and that any derivative work contains`
22			`// the original copyright notice and the associated disclaimer.`
23			`//`
24			`// This source file is free software; you can redistribute it`
25			`// and/or modify it under the terms of the GNU Lesser General`
26			`// Public License as published by the Free Software Foundation;`
27			`// either version 2.1 of the License, or (at your option) any`
28			`// later version.`
29			`//`
30			`// This source is distributed in the hope that it will be`
31			`// useful, but WITHOUT ANY WARRANTY; without even the implied`
32			`// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR`
33			`// PURPOSE. See the GNU Lesser General Public License for more`
34			`// details.`
35			`//`
36			`// You should have received a copy of the GNU Lesser General`
37			`// Public License along with this source; if not, download it`
38			`// from http://www.opencores.org/lgpl.shtml`
39			`//`
40			`///////////////////////////////////////////////////////////////////////////////////`
41			`// Additional Comments:`
42			`// http://wiki.osdev.org/Programmable_Interval_Timer`
43			`//////////////////////////////////////////////////////////////////////////////////`
44
45			`timescale 1ns / 1ps
46
47			`module timer_8253(`
48			`input CS,`
49			`input WR,`
50			`input [1:0]addr,`
51			`input [7:0]din,`
52			`output wire [7:0]dout,`
53			`input CLK_25,`
54			`input clk, // cpu CLK`
55			`output out0,`
56			`output out2`
57			`);`
58
59			`reg [8:0]rclk = 0; // rclk[8] oscillates at 1193181.8181... Hz`
60			`reg [1:0]cclk = 0;`
61
62			`always @(posedge CLK_25) begin`
63			`if(rclk[7:0] < 8'd208) rclk <= rclk + 21;`
64			`else rclk <= rclk + 57;`
65			`end`
66
67			`always @ (posedge clk) begin`
68			`cclk <= {cclk[0], rclk[8]};`
69			`end`
70
71			`wire a0 = addr == 0;`
72			`wire a2 = addr == 2;`
73			`wire a3 = addr == 3;`
74			`wire cmd0 = a3 && din[7:6] == 0;`
75			`wire cmd2 = a3 && din[7:6] == 2;`
76			`wire [7:0]dout0;`
77			`wire [7:0]dout2;`
78			`wire [7:0]mode0;`
79			`wire [7:0]mode2;`
80
81			`counter counter0 (`
82			`.CS(CS && (a0 \|\| cmd0)),`
83			`.WR(WR),`
84			`.clk(clk),`
85			`.cmd(cmd0),`
86			`.din(din),`
87			`.dout(dout0),`
88			`.mode(mode0),`
89			`.CE(cclk)`
90			`);`
91
92			`counter counter2 (`
93			`.CS(CS && (a2 \|\| cmd2)),`
94			`.WR(WR),`
95			`.clk(clk),`
96			`.cmd(cmd2),`
97			`.din(din),`
98			`.dout(dout2),`
99			`.mode(mode2),`
100			`.CE(cclk)`
101			`);`
102
103			`assign out0 = mode0[7];`
104			`assign out2 = mode2[7];`
105			`assign dout = a0 ? dout0 : dout2;`
106
107			`endmodule`
108
109
110			`module counter(`
111			`input CS,`
112			`input WR, // write cmd/data`
113			`input clk, // CPU clk`
114			`input cmd,`
115			`input [7:0]din,`
116			`output [7:0]dout,`
117			`output reg [7:0]mode, // mode[7] = output`
118			`input [1:0]CE // count enable`
119			`);`
120
121			`reg [15:0]count = 0;`
122			`reg [15:0]init = 0;`
123			`reg [1:0]state = 0; // state[1] = init reg filled`
124			`reg strobe = 0;`
125			`reg rd = 0;`
126			`reg latch = 0;`
127			`reg newcmd = 0;`
128			`wire c1 = count == 1;`
129			`wire c2 = count == 2;`
130			`reg CE1 = 0;`
131
132			`assign dout = mode[5] & (~mode[4] \| rd) ? count[15:8] : count[7:0];`
133
134			`always @(posedge clk) begin`
135
136			`if(CE == 2'b10) CE1 <= 1;`
137
138			`if(CS) begin`
139			`if(WR) begin`
140			`mode[6] <= 1;`
141			`rd <= 0;`
142			`latch <= 0;`
143			`if(cmd) begin // command`
144			`if(\|din[5:4]) begin`
145			`mode[5:0] <= din[5:0];`
146			`newcmd <= 1;`
147			`state <= {1'b0, din[5] & ~din[4]};`
148			`end else latch <= &mode[5:4];`
149			`end else begin // data`
150			`state <= state[0] + ^mode[5:4] + 1;`
151			`if(state[0]) init[15:8] <= din;`
152			`else init[7:0] <= din;`
153			`end`
154			`end else begin`
155			`rd <= ~rd;`
156			`if(rd) latch <= 0;`
157			`end`
158			`end else if(state[1] && CE1 && !latch) begin`
159			`newcmd <= 0;`
160			`CE1 <= 0;`
161			`case(mode[3:1])`
162			`3'b000, 3'b001:`
163			`if(mode[6]) begin`
164			`mode[7:6] <= 2'b00;`
165			`count <= init;`
166			`end else begin`
167			`count <= count - 1;`
168			`if(c1) mode[7] <= 1;`
169			`end`
170			`3'b010, 3'b110: begin`
171			`mode[7] <= ~c2;`
172			`if(c1 \| newcmd) begin`
173			`mode[6] <= 1'b0;`
174			`count <= init;`
175			`end else count <= count - 1;`
176			`end`
177			`3'b011, 3'b111: begin`
178			`if(c1 \| c2 \| newcmd) begin`
179			`mode[7:6] <= {~mode[7] \| newcmd, 1'b0};`
180			`count <= {init[15:1], (~mode[7] \| newcmd) & init[0]};`
181			`end else count <= count - 2;`
182			`end`
183			`3'b100, 3'b101:`
184			`if(mode[6]) begin`
185			`mode[7:6] <= 2'b10;`
186			`count <= init;`
187			`strobe <= 1;`
188			`end else begin`
189			`count <= count - 1;`
190			`if(c1) begin`
191			`if(strobe) mode[7] <= 0;`
192			`strobe <= 0;`
193			`end else mode[7] <= 1;`
194			`end`
195			`endcase`
196			`end`
197			`end`
198
199			`endmodule`

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[/] [next186mp3/] [trunk/] [HW/] [timer8253.v] - Blame information for rev 2