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/////////////////////////////////////////////////////////////////////
////                                                             ////
////  WISHBONE rev.B2 compliant synthesizable I2C Slave model    ////
////                                                             ////
////                                                             ////
////  Authors: Richard Herveille (richard@asics.ws) www.asics.ws ////
////           John Sheahan (jrsheahan@optushome.com.au)         ////
////                                                             ////
////  Downloaded from: http://www.opencores.org/projects/i2c/    ////
////                                                             ////
/////////////////////////////////////////////////////////////////////
////                                                             ////
//// Copyright (C) 2001,2002 Richard Herveille                   ////
////                         richard@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: i2c_slave_model.v,v 1.7 2006-09-04 09:08:51 rherveille Exp $
//
//  $Date: 2006-09-04 09:08:51 $
//  $Revision: 1.7 $
//  $Author: rherveille $
//  $Locker:  $
//  $State: Exp $
//
// Change History:
//               $Log: not supported by cvs2svn $
//               Revision 1.6  2005/02/28 11:33:48  rherveille
//               Fixed Tsu:sta timing check.
//               Added Thd:sta timing check.
//
//               Revision 1.5  2003/12/05 11:05:19  rherveille
//               Fixed slave address MSB='1' bug
//
//               Revision 1.4  2003/09/11 08:25:37  rherveille
//               Fixed a bug in the timing section. Changed 'tst_scl' into 'tst_sto'.
//
//               Revision 1.3  2002/10/30 18:11:06  rherveille
//               Added timing tests to i2c_model.
//               Updated testbench.
//
//               Revision 1.2  2002/03/17 10:26:38  rherveille
//               Fixed some race conditions in the i2c-slave model.
//               Added debug information.
//               Added headers.
//
 
 
module i2c_slave_model (scl, sda);
 
        //
        // parameters
        //
        parameter I2C_ADR = 7'b001_0000;
 
        //
        // input && outpus
        //
        input scl;
        inout sda;
 
        //
        // Variable declaration
        //
        wire debug = 1'b1;
 
        reg [7:0] mem [255:0]; // initiate memory
        reg [7:0] mem_adr;   // memory address
        reg [7:0] mem_do;    // memory data output
 
        reg sta, d_sta;
        reg sto, d_sto;
 
        reg [7:0] sr;        // 8bit shift register
        reg       rw;        // read/write direction
 
        wire      my_adr;    // my address called ??
        wire      i2c_reset; // i2c-statemachine reset
        reg [2:0] bit_cnt;   // 3bit downcounter
        wire      acc_done;  // 8bits transfered
        reg       ld;        // load downcounter
 
        reg       sda_o;     // sda-drive level
        wire      sda_dly;   // delayed version of sda
 
        // statemachine declaration
        parameter idle        = 3'b000;
        parameter slave_ack   = 3'b001;
        parameter get_mem_adr = 3'b010;
        parameter gma_ack     = 3'b011;
        parameter data        = 3'b100;
        parameter data_ack    = 3'b101;
 
        reg [2:0] state; // synopsys enum_state
 
        //
        // module body
        //
 
        initial
        begin
           sda_o = 1'b1;
           state = idle;
        end
 
        // generate shift register
        always @(posedge scl)
          sr <= #1 {sr[6:0],sda};
 
        //detect my_address
        assign my_adr = (sr[7:1] == I2C_ADR);
        // FIXME: This should not be a generic assign, but rather
        // qualified on address transfer phase and probably reset by stop
 
        //generate bit-counter
        always @(posedge scl)
          if(ld)
            bit_cnt <= #1 3'b111;
          else
            bit_cnt <= #1 bit_cnt - 3'h1;
 
        //generate access done signal
        assign acc_done = !(|bit_cnt);
 
        // generate delayed version of sda
        // this model assumes a hold time for sda after the falling edge of scl.
        // According to the Phillips i2c spec, there s/b a 0 ns hold time for sda
        // with regards to scl. If the data changes coincident with the clock, the
        // acknowledge is missed
        // Fix by Michael Sosnoski
        assign #1 sda_dly = sda;
 
 
        //detect start condition
        always @(negedge sda)
          if(scl)
            begin
                sta   <= #1 1'b1;
                d_sta <= #1 1'b0;
                sto   <= #1 1'b0;
 
                if(debug)
                  $display("DEBUG i2c_slave; start condition detected at %t", $time);
            end
          else
            sta <= #1 1'b0;
 
        always @(posedge scl)
          d_sta <= #1 sta;
 
        // detect stop condition
        always @(posedge sda)
          if(scl)
            begin
               sta <= #1 1'b0;
               sto <= #1 1'b1;
 
               if(debug)
                 $display("DEBUG i2c_slave; stop condition detected at %t", $time);
            end
          else
            sto <= #1 1'b0;
 
        //generate i2c_reset signal
        assign i2c_reset = sta || sto;
 
        // generate statemachine
        always @(negedge scl or posedge sto)
          if (sto || (sta && !d_sta) )
            begin
                state <= #1 idle; // reset statemachine
 
                sda_o <= #1 1'b1;
                ld    <= #1 1'b1;
            end
          else
            begin
                // initial settings
                sda_o <= #1 1'b1;
                ld    <= #1 1'b0;
 
                case(state) // synopsys full_case parallel_case
                    idle: // idle state
                      if (acc_done && my_adr)
                        begin
                            state <= #1 slave_ack;
                            rw <= #1 sr[0];
                            sda_o <= #1 1'b0; // generate i2c_ack
 
                            #2;
                            if(debug && rw)
                              $display("DEBUG i2c_slave; command byte received (read) at %t", $time);
                            if(debug && !rw)
                              $display("DEBUG i2c_slave; command byte received (write) at %t", $time);
 
                            if(rw)
                              begin
                                  mem_do <= #1 mem[mem_adr];
 
                                  if(debug)
                                    begin
                                        #2 $display("DEBUG i2c_slave; data block read %x from address %x (1)", mem_do, mem_adr);
                                        #2 $display("DEBUG i2c_slave; memcheck [%x]=%x", mem_adr, mem[mem_adr]);
                                    end
                              end
                        end
 
                    slave_ack:
                      begin
                          if(rw)
                            begin
                                state <= #1 data;
                                sda_o <= #1 mem_do[7];
                            end
                          else
                            state <= #1 get_mem_adr;
 
                          ld    <= #1 1'b1;
                      end
 
                    get_mem_adr: // wait for memory address
                      if(acc_done)
                        begin
                            state <= #1 gma_ack;
                            mem_adr <= #1 sr; // store memory address
                            sda_o <= #1 !(sr <= 255); // generate i2c_ack, for valid address
 
                            if(debug)
                              #1 $display("DEBUG i2c_slave; address received. adr=%x, ack=%b", sr, sda_o);
                        end
 
                    gma_ack:
                      begin
                          state <= #1 data;
                          ld    <= #1 1'b1;
                      end
 
                    data: // receive or drive data
                      begin
                          if(rw)
                            sda_o <= #1 mem_do[7];
 
                          if(acc_done)
                            begin
                                state <= #1 data_ack;
                                mem_adr <= #2 mem_adr + 8'h1;
                                sda_o <= #1 (rw && (mem_adr <= 255) ); // send ack on write, receive ack on read
 
                                if(rw)
                                  begin
                                      #3 mem_do <= mem[mem_adr];
 
                                      if(debug)
                                        #5 $display("DEBUG i2c_slave; data block read %x from address %x (2)", mem_do, mem_adr);
                                  end
 
                                if(!rw)
                                  begin
                                      mem[ mem_adr ] <= #1 sr; // store data in memory
 
                                      if(debug)
                                        #2 $display("DEBUG i2c_slave; data block write %x to address %x", sr, mem_adr);
                                  end
                            end
                      end
 
                    data_ack:
                      begin
                          ld <= #1 1'b1;
 
                          if(rw)
                            if(sr[0]) // read operation && master send NACK
                              begin
                                  state <= #1 idle;
                                  sda_o <= #1 1'b1;
                              end
                            else
                              begin
                                  state <= #1 data;
                                  sda_o <= #1 mem_do[7];
                              end
                          else
                            begin
                                state <= #1 data;
                                sda_o <= #1 1'b1;
                            end
                      end
 
                endcase
            end
 
        // read data from memory
        always @(posedge scl)
          if(!acc_done && rw)
            mem_do <= #1 {mem_do[6:0], 1'b1}; // insert 1'b1 for host ack generation
 
        // generate tri-states
        assign sda = sda_o ? 1'bz : 1'b0;
 
 
        //
        // Timing checks
        //
 
        wire tst_sto = sto;
        wire tst_sta = sta;
 
        specify
          specparam normal_scl_low  = 4700,
                    normal_scl_high = 4000,
                    normal_tsu_sta  = 4700,
                    normal_thd_sta  = 4000,
                    normal_tsu_sto  = 4000,
                    normal_tbuf     = 4700,
 
                    fast_scl_low  = 1300,
                    fast_scl_high =  600,
                    fast_tsu_sta  = 1300,
                    fast_thd_sta  =  600,
                    fast_tsu_sto  =  600,
                    fast_tbuf     = 1300;
 
          $width(negedge scl, normal_scl_low);  // scl low time
          $width(posedge scl, normal_scl_high); // scl high time
 
          $setup(posedge scl, negedge sda &&& scl, normal_tsu_sta); // setup start
          $setup(negedge sda &&& scl, negedge scl, normal_thd_sta); // hold start
          $setup(posedge scl, posedge sda &&& scl, normal_tsu_sto); // setup stop
 
          $setup(posedge tst_sta, posedge tst_sto, normal_tbuf); // stop to start time
        endspecify
 
endmodule
 
 

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[/] [oms8051mini/] [trunk/] [verif/] [agents/] [i2cs/] [i2c_slave_model.v] - Blame information for rev 29

Line No.	Rev	Author	Line
1	29	dinesha	`/////////////////////////////////////////////////////////////////////`
2			`//// ////`
3			`//// WISHBONE rev.B2 compliant synthesizable I2C Slave model ////`
4			`//// ////`
5			`//// ////`
6			`//// Authors: Richard Herveille (richard@asics.ws) www.asics.ws ////`
7			`//// John Sheahan (jrsheahan@optushome.com.au) ////`
8			`//// ////`
9			`//// Downloaded from: http://www.opencores.org/projects/i2c/ ////`
10			`//// ////`
11			`/////////////////////////////////////////////////////////////////////`
12			`//// ////`
13			`//// Copyright (C) 2001,2002 Richard Herveille ////`
14			`//// richard@asics.ws ////`
15			`//// ////`
16			`//// This source file may be used and distributed without ////`
17			`//// restriction provided that this copyright statement is not ////`
18			`//// removed from the file and that any derivative work contains ////`
19			`//// the original copyright notice and the associated disclaimer.////`
20			`//// ////`
21			//// THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY ////
22			`//// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED ////`
23			`//// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS ////`
24			`//// FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL THE AUTHOR ////`
25			`//// OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, ////`
26			`//// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES ////`
27			`//// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE ////`
28			`//// GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR ////`
29			`//// BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF ////`
30			`//// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT ////`
31			`//// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT ////`
32			`//// OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE ////`
33			`//// POSSIBILITY OF SUCH DAMAGE. ////`
34			`//// ////`
35			`/////////////////////////////////////////////////////////////////////`
36
37			`// CVS Log`
38			`//`
39			`// $Id: i2c_slave_model.v,v 1.7 2006-09-04 09:08:51 rherveille Exp $`
40			`//`
41			`// $Date: 2006-09-04 09:08:51 $`
42			`// $Revision: 1.7 $`
43			`// $Author: rherveille $`
44			`// $Locker: $`
45			`// $State: Exp $`
46			`//`
47			`// Change History:`
48			`// $Log: not supported by cvs2svn $`
49			`// Revision 1.6 2005/02/28 11:33:48 rherveille`
50			`// Fixed Tsu:sta timing check.`
51			`// Added Thd:sta timing check.`
52			`//`
53			`// Revision 1.5 2003/12/05 11:05:19 rherveille`
54			`// Fixed slave address MSB='1' bug`
55			`//`
56			`// Revision 1.4 2003/09/11 08:25:37 rherveille`
57			`// Fixed a bug in the timing section. Changed 'tst_scl' into 'tst_sto'.`
58			`//`
59			`// Revision 1.3 2002/10/30 18:11:06 rherveille`
60			`// Added timing tests to i2c_model.`
61			`// Updated testbench.`
62			`//`
63			`// Revision 1.2 2002/03/17 10:26:38 rherveille`
64			`// Fixed some race conditions in the i2c-slave model.`
65			`// Added debug information.`
66			`// Added headers.`
67			`//`
68
69
70			`module i2c_slave_model (scl, sda);`
71
72			`//`
73			`// parameters`
74			`//`
75			`parameter I2C_ADR = 7'b001_0000;`
76
77			`//`
78			`// input && outpus`
79			`//`
80			`input scl;`
81			`inout sda;`
82
83			`//`
84			`// Variable declaration`
85			`//`
86			`wire debug = 1'b1;`
87
88			`reg [7:0] mem [255:0]; // initiate memory`
89			`reg [7:0] mem_adr; // memory address`
90			`reg [7:0] mem_do; // memory data output`
91
92			`reg sta, d_sta;`
93			`reg sto, d_sto;`
94
95			`reg [7:0] sr; // 8bit shift register`
96			`reg rw; // read/write direction`
97
98			`wire my_adr; // my address called ??`
99			`wire i2c_reset; // i2c-statemachine reset`
100			`reg [2:0] bit_cnt; // 3bit downcounter`
101			`wire acc_done; // 8bits transfered`
102			`reg ld; // load downcounter`
103
104			`reg sda_o; // sda-drive level`
105			`wire sda_dly; // delayed version of sda`
106
107			`// statemachine declaration`
108			`parameter idle = 3'b000;`
109			`parameter slave_ack = 3'b001;`
110			`parameter get_mem_adr = 3'b010;`
111			`parameter gma_ack = 3'b011;`
112			`parameter data = 3'b100;`
113			`parameter data_ack = 3'b101;`
114
115			`reg [2:0] state; // synopsys enum_state`
116
117			`//`
118			`// module body`
119			`//`
120
121			`initial`
122			`begin`
123			`sda_o = 1'b1;`
124			`state = idle;`
125			`end`
126
127			`// generate shift register`
128			`always @(posedge scl)`
129			`sr <= #1 {sr[6:0],sda};`
130
131			`//detect my_address`
132			`assign my_adr = (sr[7:1] == I2C_ADR);`
133			`// FIXME: This should not be a generic assign, but rather`
134			`// qualified on address transfer phase and probably reset by stop`
135
136			`//generate bit-counter`
137			`always @(posedge scl)`
138			`if(ld)`
139			`bit_cnt <= #1 3'b111;`
140			`else`
141			`bit_cnt <= #1 bit_cnt - 3'h1;`
142
143			`//generate access done signal`
144			`assign acc_done = !(\|bit_cnt);`
145
146			`// generate delayed version of sda`
147			`// this model assumes a hold time for sda after the falling edge of scl.`
148			`// According to the Phillips i2c spec, there s/b a 0 ns hold time for sda`
149			`// with regards to scl. If the data changes coincident with the clock, the`
150			`// acknowledge is missed`
151			`// Fix by Michael Sosnoski`
152			`assign #1 sda_dly = sda;`
153
154
155			`//detect start condition`
156			`always @(negedge sda)`
157			`if(scl)`
158			`begin`
159			`sta <= #1 1'b1;`
160			`d_sta <= #1 1'b0;`
161			`sto <= #1 1'b0;`
162
163			`if(debug)`
164			`$display("DEBUG i2c_slave; start condition detected at %t", $time);`
165			`end`
166			`else`
167			`sta <= #1 1'b0;`
168
169			`always @(posedge scl)`
170			`d_sta <= #1 sta;`
171
172			`// detect stop condition`
173			`always @(posedge sda)`
174			`if(scl)`
175			`begin`
176			`sta <= #1 1'b0;`
177			`sto <= #1 1'b1;`
178
179			`if(debug)`
180			`$display("DEBUG i2c_slave; stop condition detected at %t", $time);`
181			`end`
182			`else`
183			`sto <= #1 1'b0;`
184
185			`//generate i2c_reset signal`
186			`assign i2c_reset = sta \|\| sto;`
187
188			`// generate statemachine`
189			`always @(negedge scl or posedge sto)`
190			`if (sto \|\| (sta && !d_sta) )`
191			`begin`
192			`state <= #1 idle; // reset statemachine`
193
194			`sda_o <= #1 1'b1;`
195			`ld <= #1 1'b1;`
196			`end`
197			`else`
198			`begin`
199			`// initial settings`
200			`sda_o <= #1 1'b1;`
201			`ld <= #1 1'b0;`
202
203			`case(state) // synopsys full_case parallel_case`
204			`idle: // idle state`
205			`if (acc_done && my_adr)`
206			`begin`
207			`state <= #1 slave_ack;`
208			`rw <= #1 sr[0];`
209			`sda_o <= #1 1'b0; // generate i2c_ack`
210
211			`#2;`
212			`if(debug && rw)`
213			`$display("DEBUG i2c_slave; command byte received (read) at %t", $time);`
214			`if(debug && !rw)`
215			`$display("DEBUG i2c_slave; command byte received (write) at %t", $time);`
216
217			`if(rw)`
218			`begin`
219			`mem_do <= #1 mem[mem_adr];`
220
221			`if(debug)`
222			`begin`
223			`#2 $display("DEBUG i2c_slave; data block read %x from address %x (1)", mem_do, mem_adr);`
224			`#2 $display("DEBUG i2c_slave; memcheck [%x]=%x", mem_adr, mem[mem_adr]);`
225			`end`
226			`end`
227			`end`
228
229			`slave_ack:`
230			`begin`
231			`if(rw)`
232			`begin`
233			`state <= #1 data;`
234			`sda_o <= #1 mem_do[7];`
235			`end`
236			`else`
237			`state <= #1 get_mem_adr;`
238
239			`ld <= #1 1'b1;`
240			`end`
241
242			`get_mem_adr: // wait for memory address`
243			`if(acc_done)`
244			`begin`
245			`state <= #1 gma_ack;`
246			`mem_adr <= #1 sr; // store memory address`
247			`sda_o <= #1 !(sr <= 255); // generate i2c_ack, for valid address`
248
249			`if(debug)`
250			`#1 $display("DEBUG i2c_slave; address received. adr=%x, ack=%b", sr, sda_o);`
251			`end`
252
253			`gma_ack:`
254			`begin`
255			`state <= #1 data;`
256			`ld <= #1 1'b1;`
257			`end`
258
259			`data: // receive or drive data`
260			`begin`
261			`if(rw)`
262			`sda_o <= #1 mem_do[7];`
263
264			`if(acc_done)`
265			`begin`
266			`state <= #1 data_ack;`
267			`mem_adr <= #2 mem_adr + 8'h1;`
268			`sda_o <= #1 (rw && (mem_adr <= 255) ); // send ack on write, receive ack on read`
269
270			`if(rw)`
271			`begin`
272			`#3 mem_do <= mem[mem_adr];`
273
274			`if(debug)`
275			`#5 $display("DEBUG i2c_slave; data block read %x from address %x (2)", mem_do, mem_adr);`
276			`end`
277
278			`if(!rw)`
279			`begin`
280			`mem[ mem_adr ] <= #1 sr; // store data in memory`
281
282			`if(debug)`
283			`#2 $display("DEBUG i2c_slave; data block write %x to address %x", sr, mem_adr);`
284			`end`
285			`end`
286			`end`
287
288			`data_ack:`
289			`begin`
290			`ld <= #1 1'b1;`
291
292			`if(rw)`
293			`if(sr[0]) // read operation && master send NACK`
294			`begin`
295			`state <= #1 idle;`
296			`sda_o <= #1 1'b1;`
297			`end`
298			`else`
299			`begin`
300			`state <= #1 data;`
301			`sda_o <= #1 mem_do[7];`
302			`end`
303			`else`
304			`begin`
305			`state <= #1 data;`
306			`sda_o <= #1 1'b1;`
307			`end`
308			`end`
309
310			`endcase`
311			`end`
312
313			`// read data from memory`
314			`always @(posedge scl)`
315			`if(!acc_done && rw)`
316			`mem_do <= #1 {mem_do[6:0], 1'b1}; // insert 1'b1 for host ack generation`
317
318			`// generate tri-states`
319			`assign sda = sda_o ? 1'bz : 1'b0;`
320
321
322			`//`
323			`// Timing checks`
324			`//`
325
326			`wire tst_sto = sto;`
327			`wire tst_sta = sta;`
328
329			`specify`
330			`specparam normal_scl_low = 4700,`
331			`normal_scl_high = 4000,`
332			`normal_tsu_sta = 4700,`
333			`normal_thd_sta = 4000,`
334			`normal_tsu_sto = 4000,`
335			`normal_tbuf = 4700,`
336
337			`fast_scl_low = 1300,`
338			`fast_scl_high = 600,`
339			`fast_tsu_sta = 1300,`
340			`fast_thd_sta = 600,`
341			`fast_tsu_sto = 600,`
342			`fast_tbuf = 1300;`
343
344			`$width(negedge scl, normal_scl_low); // scl low time`
345			`$width(posedge scl, normal_scl_high); // scl high time`
346
347			`$setup(posedge scl, negedge sda &&& scl, normal_tsu_sta); // setup start`
348			`$setup(negedge sda &&& scl, negedge scl, normal_thd_sta); // hold start`
349			`$setup(posedge scl, posedge sda &&& scl, normal_tsu_sto); // setup stop`
350
351			`$setup(posedge tst_sta, posedge tst_sto, normal_tbuf); // stop to start time`
352			`endspecify`
353
354			`endmodule`
355
356