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/////////////////////////////////////////////////////////////////////
////                                                             ////
////  Simple Baud Rate Generator                                 ////
////                                                             ////
////                                                             ////
////  Author: Rudolf Usselmann                                   ////
////          rudi@asics.ws                                      ////
////                                                             ////
////                                                             ////
////  Downloaded from: http://www.opencores.org/cores/sasc/      ////
////                                                             ////
/////////////////////////////////////////////////////////////////////
////                                                             ////
//// Copyright (C) 2000-2002 Rudolf Usselmann                    ////
////                         www.asics.ws                        ////
////                         rudi@asics.ws                       ////
////                                                             ////
//// 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 SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY     ////
//// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED   ////
//// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS   ////
//// FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL THE AUTHOR      ////
//// 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.                                 ////
////                                                             ////
/////////////////////////////////////////////////////////////////////
 
//  CVS Log
//
//  $Id: sasc_brg.v,v 1.1.1.1 2003-07-12 13:19:55 thorn_aitch Exp $
//
//  $Date: 2003-07-12 13:19:55 $
//  $Revision: 1.1.1.1 $
//  $Author: thorn_aitch $
//  $Locker:  $
//  $State: Exp $
//
// Change History:
//               $Log: not supported by cvs2svn $
//               Revision 1.1.1.1  2002/09/16 16:16:40  rudi
//               Initial Checkin
//
//
//
//
//
//
//
//
 
`include "timescale.v"
 
/*
        Baud rate Generator
        ==================
 
        div0 -  is the first stage divider
                Set this to the desired number of cycles less two
        div1 -  is the second stage divider
                Set this to the actual number of cycles
 
        Remember you have to generate a baud rate that is 4 higher than what
        you really want. This is because of the DPLL in the RX section ...
 
        Example:
        If your system clock is 50MHz and you want to generate a 9.6 Kbps baud rate:
        9600*4 = 38400KHz
        50MHz/38400KHz=1302 or 6*217
        set div0=4 (6-2) and set div1=217
 
*/
 
// Following Comments are added by Thorn Aitch, Nov.02,2002
//=========================================================
// <Actual Baud Rate>
//
//     Baud Rate = freq/[(div0 + 2)*(div1 + 1)*4]
//
//     ex)9600bps : 20MHz, div0=3, div1=103
//        20MHz/5*105*4=9524bps (error=  0.79%)            
//=========================================================
 
module sasc_brg(clk, rst, div0, div1, sio_ce, sio_ce_x4);
input           clk;
input           rst;
input   [7:0]    div0, div1;
output          sio_ce, sio_ce_x4;
 
///////////////////////////////////////////////////////////////////
//
// Local Wires and Registers
//
 
reg     [7:0]    ps;
reg             ps_clr;
reg     [7:0]    br_cnt;
reg             br_clr;
reg             sio_ce_x4_r;
reg     [1:0]    cnt;
reg             sio_ce, sio_ce_x4;
reg             sio_ce_r ;
reg             sio_ce_x4_t;
 
///////////////////////////////////////////////////////////////////
//
// Boud Rate Generator
//
 
// -----------------------------------------------------
// Prescaler
always @(posedge clk)
        if(!rst)        ps <= #1 8'h0;
        else
        if(ps_clr)      ps <= #1 8'h0;
        else            ps <= #1 ps + 8'h1;
 
always @(posedge clk)
        ps_clr <= #1 (ps == div0);      // Desired number of cycles less 2
 
// -----------------------------------------------------
// Oversampled Boud Rate (x4)
always @(posedge clk)
        if(!rst)        br_cnt <= #1 8'h0;
        else
        if(br_clr)      br_cnt <= #1 8'h0;
//      else            br_cnt <= #1 br_cnt + 8'h1;      // *** Deleted *** Oct.30,2002 Thorn Aitch
        else if (ps_clr) br_cnt <= #1 br_cnt + 8'h1; // *** Added   *** Oct.30,2002 Thorn Aitch
 
 
always @(posedge clk)
        br_clr <= #1 (br_cnt == div1); // Prciese number of PS cycles
 
always @(posedge clk)
        sio_ce_x4_r <= #1 br_clr;
 
always @(posedge clk)
        sio_ce_x4_t <= #1 !sio_ce_x4_r & br_clr;
 
always @(posedge clk)
        sio_ce_x4 <= #1 sio_ce_x4_t;
 
// -----------------------------------------------------
// Actual Boud rate
always @(posedge clk)
        if(!rst)                        cnt <= #1 2'h0;
        else
        if(!sio_ce_x4_r & br_clr)       cnt <= #1 cnt + 2'h1;
 
always @(posedge clk)
        sio_ce_r <= #1 (cnt == 2'h0);
 
always @(posedge clk)
        sio_ce <= #1 !sio_ce_r & (cnt == 2'h0);
 
endmodule
 

Line No.	Rev	Author	Line
1	2	thorn_aitc	`/////////////////////////////////////////////////////////////////////`
2			`//// ////`
3			`//// Simple Baud Rate Generator ////`
4			`//// ////`
5			`//// ////`
6			`//// Author: Rudolf Usselmann ////`
7			`//// rudi@asics.ws ////`
8			`//// ////`
9			`//// ////`
10			`//// Downloaded from: http://www.opencores.org/cores/sasc/ ////`
11			`//// ////`
12			`/////////////////////////////////////////////////////////////////////`
13			`//// ////`
14			`//// Copyright (C) 2000-2002 Rudolf Usselmann ////`
15			`//// www.asics.ws ////`
16			`//// rudi@asics.ws ////`
17			`//// ////`
18			`//// This source file may be used and distributed without ////`
19			`//// restriction provided that this copyright statement is not ////`
20			`//// removed from the file and that any derivative work contains ////`
21			`//// the original copyright notice and the associated disclaimer.////`
22			`//// ////`
23			//// THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY ////
24			`//// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED ////`
25			`//// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS ////`
26			`//// FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL THE AUTHOR ////`
27			`//// OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, ////`
28			`//// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES ////`
29			`//// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE ////`
30			`//// GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR ////`
31			`//// BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF ////`
32			`//// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT ////`
33			`//// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT ////`
34			`//// OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE ////`
35			`//// POSSIBILITY OF SUCH DAMAGE. ////`
36			`//// ////`
37			`/////////////////////////////////////////////////////////////////////`
38
39			`// CVS Log`
40			`//`
41			`// $Id: sasc_brg.v,v 1.1.1.1 2003-07-12 13:19:55 thorn_aitch Exp $`
42			`//`
43			`// $Date: 2003-07-12 13:19:55 $`
44			`// $Revision: 1.1.1.1 $`
45			`// $Author: thorn_aitch $`
46			`// $Locker: $`
47			`// $State: Exp $`
48			`//`
49			`// Change History:`
50			`// $Log: not supported by cvs2svn $`
51			`// Revision 1.1.1.1 2002/09/16 16:16:40 rudi`
52			`// Initial Checkin`
53			`//`
54			`//`
55			`//`
56			`//`
57			`//`
58			`//`
59			`//`
60			`//`
61
62			`include "timescale.v"
63
64			`/*`
65			`Baud rate Generator`
66			`==================`
67
68			`div0 - is the first stage divider`
69			`Set this to the desired number of cycles less two`
70			`div1 - is the second stage divider`
71			`Set this to the actual number of cycles`
72
73			`Remember you have to generate a baud rate that is 4 higher than what`
74			`you really want. This is because of the DPLL in the RX section ...`
75
76			`Example:`
77			`If your system clock is 50MHz and you want to generate a 9.6 Kbps baud rate:`
78			`9600*4 = 38400KHz`
79			`50MHz/38400KHz=1302 or 6*217`
80			`set div0=4 (6-2) and set div1=217`
81
82			`*/`
83
84			`// Following Comments are added by Thorn Aitch, Nov.02,2002`
85			`//=========================================================`
86			`// <Actual Baud Rate>`
87			`//`
88			`// Baud Rate = freq/[(div0 + 2)(div1 + 1)4]`
89			`//`
90			`// ex)9600bps : 20MHz, div0=3, div1=103`
91			`// 20MHz/51054=9524bps (error= 0.79%)`
92			`//=========================================================`
93
94			`module sasc_brg(clk, rst, div0, div1, sio_ce, sio_ce_x4);`
95			`input clk;`
96			`input rst;`
97			`input [7:0] div0, div1;`
98			`output sio_ce, sio_ce_x4;`
99
100			`///////////////////////////////////////////////////////////////////`
101			`//`
102			`// Local Wires and Registers`
103			`//`
104
105			`reg [7:0] ps;`
106			`reg ps_clr;`
107			`reg [7:0] br_cnt;`
108			`reg br_clr;`
109			`reg sio_ce_x4_r;`
110			`reg [1:0] cnt;`
111			`reg sio_ce, sio_ce_x4;`
112			`reg sio_ce_r ;`
113			`reg sio_ce_x4_t;`
114
115			`///////////////////////////////////////////////////////////////////`
116			`//`
117			`// Boud Rate Generator`
118			`//`
119
120			`// -----------------------------------------------------`
121			`// Prescaler`
122			`always @(posedge clk)`
123			`if(!rst) ps <= #1 8'h0;`
124			`else`
125			`if(ps_clr) ps <= #1 8'h0;`
126			`else ps <= #1 ps + 8'h1;`
127
128			`always @(posedge clk)`
129			`ps_clr <= #1 (ps == div0); // Desired number of cycles less 2`
130
131			`// -----------------------------------------------------`
132			`// Oversampled Boud Rate (x4)`
133			`always @(posedge clk)`
134			`if(!rst) br_cnt <= #1 8'h0;`
135			`else`
136			`if(br_clr) br_cnt <= #1 8'h0;`
137			`// else br_cnt <= #1 br_cnt + 8'h1; // * Deleted * Oct.30,2002 Thorn Aitch`
138			`else if (ps_clr) br_cnt <= #1 br_cnt + 8'h1; // * Added * Oct.30,2002 Thorn Aitch`
139
140
141			`always @(posedge clk)`
142			`br_clr <= #1 (br_cnt == div1); // Prciese number of PS cycles`
143
144			`always @(posedge clk)`
145			`sio_ce_x4_r <= #1 br_clr;`
146
147			`always @(posedge clk)`
148			`sio_ce_x4_t <= #1 !sio_ce_x4_r & br_clr;`
149
150			`always @(posedge clk)`
151			`sio_ce_x4 <= #1 sio_ce_x4_t;`
152
153			`// -----------------------------------------------------`
154			`// Actual Boud rate`
155			`always @(posedge clk)`
156			`if(!rst) cnt <= #1 2'h0;`
157			`else`
158			`if(!sio_ce_x4_r & br_clr) cnt <= #1 cnt + 2'h1;`
159
160			`always @(posedge clk)`
161			`sio_ce_r <= #1 (cnt == 2'h0);`
162
163			`always @(posedge clk)`
164			`sio_ce <= #1 !sio_ce_r & (cnt == 2'h0);`
165
166			`endmodule`
167

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[/] [Aquarius/] [trunk/] [verilog/] [sasc_brg.v] - Blame information for rev 2