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//----------------------------------------------------------------------------
// Copyright (C) 2009 , Olivier Girard
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above copyright
//       notice, this list of conditions and the following disclaimer in the
//       documentation and/or other materials provided with the distribution.
//     * Neither the name of the authors nor the names of its contributors
//       may be used to endorse or promote products derived from this software
//       without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
// OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
// THE POSSIBILITY OF SUCH DAMAGE
//
//----------------------------------------------------------------------------
//
// *File Name: omsp_clock_mux.v
//
// *Module Description:
//                       Standard clock mux for the openMSP430
//
// *Author(s):
//              - Olivier Girard,    olgirard@gmail.com
//
//----------------------------------------------------------------------------
// $Rev: 103 $
// $LastChangedBy: olivier.girard $
// $LastChangedDate: 2011-03-05 15:44:48 +0100 (Sat, 05 Mar 2011) $
//----------------------------------------------------------------------------
 
module  omsp_clock_mux (
 
// OUTPUTs
    clk_out,                   // Clock output
 
// INPUTs
    clk_in0,                   // Clock input 0
    clk_in1,                   // Clock input 1
    reset,                     // Reset
    scan_mode,                 // Scan mode (clk_in0 is selected in scan mode)
    select_in                  // Clock selection
);
 
// OUTPUTs
//=========
output         clk_out;        // Clock output
 
// INPUTs
//=========
input          clk_in0;        // Clock input 0
input          clk_in1;        // Clock input 1
input          reset;          // Reset
input          scan_mode;      // Scan mode (clk_in0 is selected in scan mode)
input          select_in;      // Clock selection
 
 
//===========================================================================================================================//
// 1)  CLOCK MUX                                                                                                             //
//===========================================================================================================================//
//                                                                                                                           //
//    The following (glitch free) clock mux is implemented as following:                                                     //
//                                                                                                                           //
//                                                                                                                           //
//                                                                                                                           //
//                                                                                                                           //
//                                   +-----.     +--------+   +--------+                                                     //
//    select_in >>----+-------------O|      \    |        |   |        |          +-----.                                    //
//                    |              |       |---| D    Q |---| D    Q |--+-------|      \                                   //
//                    |     +-------O|      /    |        |   |        |  |       |       |O-+                               //
//                    |     |        +-----'     |        |   |        |  |   +--O|      /   |                               //
//                    |     |                    |   /\   |   |   /\   |  |   |   +-----'    |                               //
//                    |     |                    +--+--+--+   +--+--+--+  |   |              |                               //
//                    |     |                        O            |       |   |              |                               //
//                    |     |                        |            |       |   |              |  +-----.                      //
//       clk_in0 >>----------------------------------+------------+-----------+              +--|      \                     //
//                    |     |                                             |                     |       |----<< clk_out      //
//                    |     |     +---------------------------------------+                  +--|      /                     //
//                    |     |     |                                                          |  +-----'                      //
//                    |     +---------------------------------------------+                  |                               //
//                    |           |                                       |                  |                               //
//                    |           |  +-----.     +--------+   +--------+  |                  |                               //
//                    |           +-O|      \    |        |   |        |  |       +-----.    |                               //
//                    |              |       |---| D    Q |---| D    Q |--+-------|      \   |                               //
//                    +--------------|      /    |        |   |        |          |       |O-+                               //
//                                   +-----'     |        |   |        |      +--O|      /                                   //
//                                               |   /\   |   |   /\   |      |   +-----'                                    //
//                                               +--+--+--+   +--+--+--+      |                                              //
//                                                   O            |           |                                              //
//                                                   |            |           |                                              //
//       clk_in1 >>----------------------------------+------------+-----------+                                              //
//                                                                                                                           //
//                                                                                                                           //
//===========================================================================================================================//
 
//-----------------------------------------------------------------------------
// Wire declarations
//-----------------------------------------------------------------------------
 
wire in0_select;
reg  in0_select_s;
reg  in0_select_ss;
wire in0_enable;
 
wire in1_select;
reg  in1_select_s;
reg  in1_select_ss;
wire in1_enable;
 
wire clk_in0_inv;
wire clk_in1_inv;
wire gated_clk_in0;
wire gated_clk_in1;
 
 
//-----------------------------------------------------------------------------
// CLK_IN0 Selection
//-----------------------------------------------------------------------------
 
assign in0_select = ~select_in & ~in1_select_ss;
 
always @ (posedge clk_in0_inv or posedge reset)
  if (reset) in0_select_s  <=  1'b1;
  else       in0_select_s  <=  in0_select;
 
always @ (posedge clk_in0     or posedge reset)
  if (reset) in0_select_ss <=  1'b1;
  else       in0_select_ss <=  in0_select_s;
 
assign in0_enable = in0_select_ss | scan_mode;
 
 
//-----------------------------------------------------------------------------
// CLK_IN1 Selection
//-----------------------------------------------------------------------------
 
assign in1_select =  select_in & ~in0_select_ss;
 
always @ (posedge clk_in1_inv or posedge reset)
  if (reset) in1_select_s  <=  1'b0;
  else       in1_select_s  <=  in1_select;
 
always @ (posedge clk_in1     or posedge reset)
  if (reset) in1_select_ss <=  1'b0;
  else       in1_select_ss <=  in1_select_s;
 
assign in1_enable = in1_select_ss & ~scan_mode;
 
 
//-----------------------------------------------------------------------------
// Clock MUX
//-----------------------------------------------------------------------------
//
// IMPORTANT NOTE:
//                  Because the clock network is a critical part of the design,
//                 the following combinatorial logic should be replaced with
//                 direct instanciation of standard cells from target library.
//                  Don't forget the "dont_touch" attribute to make sure
//                 synthesis won't mess it up.
//
 
// Replace with standard cell INVERTER
assign clk_in0_inv   = ~clk_in0;
assign clk_in1_inv   = ~clk_in1;
 
 
// Replace with standard cell NAND2
assign gated_clk_in0 = ~(clk_in0_inv & in0_enable);
assign gated_clk_in1 = ~(clk_in1_inv & in1_enable);
 
 
// Replace with standard cell AND2
assign clk_out       =  (gated_clk_in0 & gated_clk_in1);
 
 
 
endmodule // omsp_clock_gate

Line No.	Rev	Author	Line
1	136	olivier.gi	`//----------------------------------------------------------------------------`
2			`// Copyright (C) 2009 , Olivier Girard`
3			`//`
4			`// Redistribution and use in source and binary forms, with or without`
5			`// modification, are permitted provided that the following conditions`
6			`// are met:`
7			`// * Redistributions of source code must retain the above copyright`
8			`// notice, this list of conditions and the following disclaimer.`
9			`// * Redistributions in binary form must reproduce the above copyright`
10			`// notice, this list of conditions and the following disclaimer in the`
11			`// documentation and/or other materials provided with the distribution.`
12			`// * Neither the name of the authors nor the names of its contributors`
13			`// may be used to endorse or promote products derived from this software`
14			`// without specific prior written permission.`
15			`//`
16			`// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"`
17			`// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE`
18			`// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE`
19			`// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE`
20			`// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,`
21			`// OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF`
22			`// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS`
23			`// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN`
24			`// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)`
25			`// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF`
26			`// THE POSSIBILITY OF SUCH DAMAGE`
27			`//`
28			`//----------------------------------------------------------------------------`
29			`//`
30			`// *File Name: omsp_clock_mux.v`
31	202	olivier.gi	`//`
32	136	olivier.gi	`// *Module Description:`
33			`// Standard clock mux for the openMSP430`
34			`//`
35			`// *Author(s):`
36			`// - Olivier Girard, olgirard@gmail.com`
37			`//`
38			`//----------------------------------------------------------------------------`
39			`// $Rev: 103 $`
40			`// $LastChangedBy: olivier.girard $`
41			`// $LastChangedDate: 2011-03-05 15:44:48 +0100 (Sat, 05 Mar 2011) $`
42			`//----------------------------------------------------------------------------`
43
44			`module omsp_clock_mux (`
45
46			`// OUTPUTs`
47			`clk_out, // Clock output`
48
49			`// INPUTs`
50			`clk_in0, // Clock input 0`
51			`clk_in1, // Clock input 1`
52			`reset, // Reset`
53			`scan_mode, // Scan mode (clk_in0 is selected in scan mode)`
54	202	olivier.gi	`select_in // Clock selection`
55	136	olivier.gi	`);`
56
57			`// OUTPUTs`
58			`//=========`
59			`output clk_out; // Clock output`
60
61			`// INPUTs`
62			`//=========`
63			`input clk_in0; // Clock input 0`
64			`input clk_in1; // Clock input 1`
65			`input reset; // Reset`
66			`input scan_mode; // Scan mode (clk_in0 is selected in scan mode)`
67	202	olivier.gi	`input select_in; // Clock selection`
68	136	olivier.gi
69
70			`//===========================================================================================================================//`
71			`// 1) CLOCK MUX //`
72			`//===========================================================================================================================//`
73			`// //`
74			`// The following (glitch free) clock mux is implemented as following: //`
75			`// //`
76			`// //`
77			`// //`
78			`// //`
79			`// +-----. +--------+ +--------+ //`
80	202	olivier.gi	`// select_in >>----+-------------O\| \ \| \| \| \| +-----. //`
81	136	olivier.gi	`// \| \| \|---\| D Q \|---\| D Q \|--+-------\| \ //`
82			`// \| +-------O\| / \| \| \| \| \| \| \|O-+ //`
83			`// \| \| +-----' \| \| \| \| \| +--O\| / \| //`
84			`// \| \| \| /\ \| \| /\ \| \| \| +-----' \| //`
85			`// \| \| +--+--+--+ +--+--+--+ \| \| \| //`
86			`// \| \| O \| \| \| \| //`
87			`// \| \| \| \| \| \| \| +-----. //`
88			`// clk_in0 >>----------------------------------+------------+-----------+ +--\| \ //`
89			`// \| \| \| \| \|----<< clk_out //`
90			`// \| \| +---------------------------------------+ +--\| / //`
91			`// \| \| \| \| +-----' //`
92			`// \| +---------------------------------------------+ \| //`
93			`// \| \| \| \| //`
94			`// \| \| +-----. +--------+ +--------+ \| \| //`
95			`// \| +-O\| \ \| \| \| \| \| +-----. \| //`
96			`// \| \| \|---\| D Q \|---\| D Q \|--+-------\| \ \| //`
97			`// +--------------\| / \| \| \| \| \| \|O-+ //`
98			`// +-----' \| \| \| \| +--O\| / //`
99			`// \| /\ \| \| /\ \| \| +-----' //`
100			`// +--+--+--+ +--+--+--+ \| //`
101			`// O \| \| //`
102			`// \| \| \| //`
103			`// clk_in1 >>----------------------------------+------------+-----------+ //`
104			`// //`
105			`// //`
106			`//===========================================================================================================================//`
107
108			`//-----------------------------------------------------------------------------`
109			`// Wire declarations`
110			`//-----------------------------------------------------------------------------`
111	202	olivier.gi
112	136	olivier.gi	`wire in0_select;`
113			`reg in0_select_s;`
114			`reg in0_select_ss;`
115			`wire in0_enable;`
116
117			`wire in1_select;`
118			`reg in1_select_s;`
119			`reg in1_select_ss;`
120			`wire in1_enable;`
121
122			`wire clk_in0_inv;`
123			`wire clk_in1_inv;`
124			`wire gated_clk_in0;`
125			`wire gated_clk_in1;`
126
127
128			`//-----------------------------------------------------------------------------`
129			`// CLK_IN0 Selection`
130			`//-----------------------------------------------------------------------------`
131	202	olivier.gi
132			`assign in0_select = ~select_in & ~in1_select_ss;`
133
134	136	olivier.gi	`always @ (posedge clk_in0_inv or posedge reset)`
135			`if (reset) in0_select_s <= 1'b1;`
136			`else in0_select_s <= in0_select;`
137
138			`always @ (posedge clk_in0 or posedge reset)`
139			`if (reset) in0_select_ss <= 1'b1;`
140			`else in0_select_ss <= in0_select_s;`
141
142			`assign in0_enable = in0_select_ss \| scan_mode;`
143
144
145			`//-----------------------------------------------------------------------------`
146			`// CLK_IN1 Selection`
147			`//-----------------------------------------------------------------------------`
148	202	olivier.gi
149			`assign in1_select = select_in & ~in0_select_ss;`
150
151	136	olivier.gi	`always @ (posedge clk_in1_inv or posedge reset)`
152			`if (reset) in1_select_s <= 1'b0;`
153			`else in1_select_s <= in1_select;`
154
155			`always @ (posedge clk_in1 or posedge reset)`
156			`if (reset) in1_select_ss <= 1'b0;`
157			`else in1_select_ss <= in1_select_s;`
158
159			`assign in1_enable = in1_select_ss & ~scan_mode;`
160
161	202	olivier.gi
162	136	olivier.gi	`//-----------------------------------------------------------------------------`
163			`// Clock MUX`
164			`//-----------------------------------------------------------------------------`
165			`//`
166			`// IMPORTANT NOTE:`
167			`// Because the clock network is a critical part of the design,`
168			`// the following combinatorial logic should be replaced with`
169			`// direct instanciation of standard cells from target library.`
170			`// Don't forget the "dont_touch" attribute to make sure`
171			`// synthesis won't mess it up.`
172			`//`
173
174			`// Replace with standard cell INVERTER`
175			`assign clk_in0_inv = ~clk_in0;`
176			`assign clk_in1_inv = ~clk_in1;`
177
178
179			`// Replace with standard cell NAND2`
180			`assign gated_clk_in0 = ~(clk_in0_inv & in0_enable);`
181			`assign gated_clk_in1 = ~(clk_in1_inv & in1_enable);`
182
183	202	olivier.gi
184	136	olivier.gi	`// Replace with standard cell AND2`
185			`assign clk_out = (gated_clk_in0 & gated_clk_in1);`
186
187
188
189			`endmodule // omsp_clock_gate`

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[/] [openmsp430/] [trunk/] [fpga/] [xilinx_diligent_s3board/] [rtl/] [verilog/] [openmsp430/] [omsp_clock_mux.v] - Blame information for rev 202