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[/] [openrisc/] [trunk/] [orpsocv2/] [bench/] [verilog/] [mt48lc16m16a2.v] - Blame information for rev 495

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1 6 julius 
/**************************************************************************
2 
*
3 
*    File Name:  MT48LC16M16A2.V
4 
*      Version:  2.1
5 
*         Date:  June 6th, 2002
6 
*        Model:  BUS Functional
7 
*    Simulator:  Model Technology
8 
*
9 
* Dependencies:  None
10 
*
11 
*        Email:  modelsupport@micron.com
12 
*      Company:  Micron Technology, Inc.
13 
*        Model:  MT48LC16M16A2 (4Meg x 16 x 4 Banks)
14 
*
15 
*  Description:  Micron 256Mb SDRAM Verilog model
16 
*
17 
*   Limitation:  - Doesn't check for 8192 cycle refresh
18 
*
19 
*         Note:  - Set simulator resolution to "ps" accuracy
20 
*                - Set Debug = 0 to disable $display messages
21 
*
22 
*   Disclaimer:  THESE DESIGNS ARE PROVIDED "AS IS" WITH NO WARRANTY
23 
*                WHATSOEVER AND MICRON SPECIFICALLY DISCLAIMS ANY
24 
*                IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR
25 
*                A PARTICULAR PURPOSE, OR AGAINST INFRINGEMENT.
26 
*
27 
*                Copyright © 2001 Micron Semiconductor Products, Inc.
28 
*                All rights researved
29 
*
30 
* Rev  Author          Date        Changes
31 
* ---  --------------------------  ---------------------------------------
32 
* 2.1  SH              06/06/2002  - Typo in bank multiplex
33 
*      Micron Technology Inc.
34 
*
35 
* 2.0  SH              04/30/2002  - Second release
36 
*      Micron Technology Inc.
37 
*
38 
**************************************************************************/
39 
 
40 44 julius 
`include "timescale.v"
41 403 julius 
`include "test-defines.v"
42 6 julius 
 
43 403 julius 
// Uncomment one of the following to have the appropriate size definitions
44 
// for the part.
45 
//`define MT48LC32M16   // 64MB part
46 
`define MT48LC16M16   // 32MB part
47 
//`define MT48LC4M16    //  8MB part
48 
 
49 6 julius 
module mt48lc16m16a2 (Dq, Addr, Ba, Clk, Cke, Cs_n, Ras_n, Cas_n, We_n, Dqm);
50 
 
51 
 
52 403 julius 
`ifdef MT48LC32M16
53 
   // Params. for  mt48lc32m16a2 (64MB part)
54 
   parameter addr_bits =      13;
55 
   parameter col_bits  =      10;
56 495 julius 
   parameter mem_sizes = 8388608;
57 403 julius 
`endif
58 
 
59 
`ifdef MT48LC16M16
60 
   // Params. for  mt48lc16m16a2 (32MB part)
61 
   parameter addr_bits =      13;
62 
   parameter col_bits  =       9;
63 495 julius 
   parameter mem_sizes = 4194304;
64 403 julius 
`endif
65 
 
66 
`ifdef MT48LC4M16
67 495 julius 
   //Params for mt48lc4m16a2 (8MB part)
68 403 julius 
   parameter addr_bits =      12;
69 
   parameter col_bits  =       8;
70 495 julius 
   parameter mem_sizes =   1048576;
71 403 julius 
`endif
72 
 
73 
   // Common to all parts
74 
   parameter data_bits =      16;
75 
 
76 495 julius 
   inout     [data_bits - 1 : 0] Dq;
77 
   input [addr_bits - 1 : 0]      Addr;
78 
   input [1 : 0]                  Ba;
79 
   input                         Clk;
80 
   input                         Cke;
81 
   input                         Cs_n;
82 
   input                         Ras_n;
83 
   input                         Cas_n;
84 
   input                         We_n;
85 
   input [1 : 0]                  Dqm;
86 403 julius 
 
87 495 julius 
   reg [data_bits - 1 : 0]        Bank0 [0 : mem_sizes];
88 
   reg [data_bits - 1 : 0]        Bank1 [0 : mem_sizes];
89 
   reg [data_bits - 1 : 0]        Bank2 [0 : mem_sizes];
90 
   reg [data_bits - 1 : 0]        Bank3 [0 : mem_sizes];
91 
   reg [31 : 0]           Bank0_32bit [0 : (mem_sizes/2)]; // Temporary 32-bit wide array to hold readmemh()'d data before loading into 16-bit wide array
92 6 julius 
    reg                   [1 : 0] Bank_addr [0 : 3];                // Bank Address Pipeline
93 
    reg        [col_bits - 1 : 0] Col_addr [0 : 3];                 // Column Address Pipeline
94 
    reg                   [3 : 0] Command [0 : 3];                  // Command Operation Pipeline
95 
    reg                   [1 : 0] Dqm_reg0, Dqm_reg1;               // DQM Operation Pipeline
96 
    reg       [addr_bits - 1 : 0] B0_row_addr, B1_row_addr, B2_row_addr, B3_row_addr;
97 
 
98 
    reg       [addr_bits - 1 : 0] Mode_reg;
99 
    reg       [data_bits - 1 : 0] Dq_reg, Dq_dqm;
100 
    reg        [col_bits - 1 : 0] Col_temp, Burst_counter;
101 
 
102 
    reg                           Act_b0, Act_b1, Act_b2, Act_b3;   // Bank Activate
103 
    reg                           Pc_b0, Pc_b1, Pc_b2, Pc_b3;       // Bank Precharge
104 
 
105 
    reg                   [1 : 0] Bank_precharge       [0 : 3];     // Precharge Command
106 
    reg                           A10_precharge        [0 : 3];     // Addr[10] = 1 (All banks)
107 
    reg                           Auto_precharge       [0 : 3];     // RW Auto Precharge (Bank)
108 
    reg                           Read_precharge       [0 : 3];     // R  Auto Precharge
109 
    reg                           Write_precharge      [0 : 3];     //  W Auto Precharge
110 
    reg                           RW_interrupt_read    [0 : 3];     // RW Interrupt Read with Auto Precharge
111 
    reg                           RW_interrupt_write   [0 : 3];     // RW Interrupt Write with Auto Precharge
112 
    reg                   [1 : 0] RW_interrupt_bank;                // RW Interrupt Bank
113 
    integer                       RW_interrupt_counter [0 : 3];     // RW Interrupt Counter
114 
    integer                       Count_precharge      [0 : 3];     // RW Auto Precharge Counter
115 
 
116 
    reg                           Data_in_enable;
117 
    reg                           Data_out_enable;
118 
 
119 
    reg                   [1 : 0] Bank, Prev_bank;
120 
    reg       [addr_bits - 1 : 0] Row;
121 
    reg        [col_bits - 1 : 0] Col, Col_brst;
122 
 
123 
    // Internal system clock
124 
    reg                           CkeZ, Sys_clk;
125 
 
126 
    // Commands Decode
127 
    wire      Active_enable    = ~Cs_n & ~Ras_n &  Cas_n &  We_n;
128 
    wire      Aref_enable      = ~Cs_n & ~Ras_n & ~Cas_n &  We_n;
129 
    wire      Burst_term       = ~Cs_n &  Ras_n &  Cas_n & ~We_n;
130 
    wire      Mode_reg_enable  = ~Cs_n & ~Ras_n & ~Cas_n & ~We_n;
131 
    wire      Prech_enable     = ~Cs_n & ~Ras_n &  Cas_n & ~We_n;
132 
    wire      Read_enable      = ~Cs_n &  Ras_n & ~Cas_n &  We_n;
133 
    wire      Write_enable     = ~Cs_n &  Ras_n & ~Cas_n & ~We_n;
134 
 
135 
    // Burst Length Decode
136 
    wire      Burst_length_1   = ~Mode_reg[2] & ~Mode_reg[1] & ~Mode_reg[0];
137 
    wire      Burst_length_2   = ~Mode_reg[2] & ~Mode_reg[1] &  Mode_reg[0];
138 
    wire      Burst_length_4   = ~Mode_reg[2] &  Mode_reg[1] & ~Mode_reg[0];
139 
    wire      Burst_length_8   = ~Mode_reg[2] &  Mode_reg[1] &  Mode_reg[0];
140 
    wire      Burst_length_f   =  Mode_reg[2] &  Mode_reg[1] &  Mode_reg[0];
141 
 
142 
    // CAS Latency Decode
143 
    wire      Cas_latency_2    = ~Mode_reg[6] &  Mode_reg[5] & ~Mode_reg[4];
144 
    wire      Cas_latency_3    = ~Mode_reg[6] &  Mode_reg[5] &  Mode_reg[4];
145 
 
146 
    // Write Burst Mode
147 
    wire      Write_burst_mode = Mode_reg[9];
148 
 
149 
    wire      Debug            = 1'b0;                          // Debug messages : 1 = On
150 
    wire      Dq_chk           = Sys_clk & Data_in_enable;      // Check setup/hold time for DQ
151 
 
152 
    assign    Dq               = Dq_reg;                        // DQ buffer
153 
 
154 
    // Commands Operation
155 
    `define   ACT       0
156 
    `define   NOP       1
157 
    `define   READ      2
158 
    `define   WRITE     3
159 
    `define   PRECH     4
160 
    `define   A_REF     5
161 
    `define   BST       6
162 
    `define   LMR       7
163 
 
164 
    // Timing Parameters for -7E PC133 CL2
165 
    parameter tAC  =   5.4;
166 
    parameter tHZ  =   5.4;
167 
    parameter tOH  =   3.0;
168 
    parameter tMRD =   2.0;     // 2 Clk Cycles
169 
    parameter tRAS =  37.0;
170 
    parameter tRC  =  60.0;
171 
    parameter tRCD =  15.0;
172 
    parameter tRFC =  66.0;
173 
    parameter tRP  =  15.0;
174 
    parameter tRRD =  14.0;
175 
    parameter tWRa =   7.0;     // A2 Version - Auto precharge mode (1 Clk + 7 ns)
176 
    parameter tWRm =  14.0;     // A2 Version - Manual precharge mode (14 ns)
177 
 
178 
    // Timing Check variable
179 
    time  MRD_chk;
180 
    time  WR_chkm [0 : 3];
181 
    time  RFC_chk, RRD_chk;
182 
    time  RC_chk0, RC_chk1, RC_chk2, RC_chk3;
183 
    time  RAS_chk0, RAS_chk1, RAS_chk2, RAS_chk3;
184 
    time  RCD_chk0, RCD_chk1, RCD_chk2, RCD_chk3;
185 
    time  RP_chk0, RP_chk1, RP_chk2, RP_chk3;
186 
 
187 403 julius 
   integer mem_cnt;
188 
 
189 
 
190 6 julius 
    initial begin
191 
        Dq_reg = {data_bits{1'bz}};
192 
        Data_in_enable = 0; Data_out_enable = 0;
193 
        Act_b0 = 1; Act_b1 = 1; Act_b2 = 1; Act_b3 = 1;
194 
        Pc_b0 = 0; Pc_b1 = 0; Pc_b2 = 0; Pc_b3 = 0;
195 
        WR_chkm[0] = 0; WR_chkm[1] = 0; WR_chkm[2] = 0; WR_chkm[3] = 0;
196 
        RW_interrupt_read[0] = 0; RW_interrupt_read[1] = 0; RW_interrupt_read[2] = 0; RW_interrupt_read[3] = 0;
197 
        RW_interrupt_write[0] = 0; RW_interrupt_write[1] = 0; RW_interrupt_write[2] = 0; RW_interrupt_write[3] = 0;
198 
        MRD_chk = 0; RFC_chk = 0; RRD_chk = 0;
199 
        RAS_chk0 = 0; RAS_chk1 = 0; RAS_chk2 = 0; RAS_chk3 = 0;
200 
        RCD_chk0 = 0; RCD_chk1 = 0; RCD_chk2 = 0; RCD_chk3 = 0;
201 
        RC_chk0 = 0; RC_chk1 = 0; RC_chk2 = 0; RC_chk3 = 0;
202 
        RP_chk0 = 0; RP_chk1 = 0; RP_chk2 = 0; RP_chk3 = 0;
203 
        $timeformat (-9, 1, " ns", 12);
204 403 julius 
//`define INIT_CLEAR_MEM_BANKS
205 
`ifdef INIT_CLEAR_MEM_BANKS // Added, jb
206 
       // Initialse the memory before we use it, clearing x's
207 
       for(mem_cnt = 0; mem_cnt < mem_sizes; mem_cnt = mem_cnt + 1)
208 
         begin
209 
            Bank0[mem_cnt] = 0;
210 
            Bank1[mem_cnt] = 0;
211 
            Bank2[mem_cnt] = 0;
212 
            Bank3[mem_cnt] = 0;
213 
         end
214 
`endif
215 6 julius 
 
216 403 julius 
`ifdef PRELOAD_RAM // Added jb
217 
       $display("* Preloading SDRAM bank 0.\n");
218 
       // Uses the vmem file for the internal SRAM, so words are 32-bits wide
219 
       // and we need to copy them into the 16-bit wide array, which the simulator
220 
       // can't figure out how to do, so we'll do it manually here.
221 
       $readmemh("sram.vmem", Bank0_32bit);
222 
       for (mem_cnt=0;mem_cnt < (mem_sizes/2); mem_cnt = mem_cnt + 1)
223 
         begin
224 
            Bank0[(mem_cnt*2)+1] = Bank0_32bit[mem_cnt][15:0];
225 
            Bank0[(mem_cnt*2)] = Bank0_32bit[mem_cnt][31:16];
226 
         end
227 
`endif
228 
end
229 
 
230 6 julius 
    // System clock generator
231 
    always begin
232 
        @ (posedge Clk) begin
233 
            Sys_clk = CkeZ;
234 
            CkeZ = Cke;
235 
        end
236 
        @ (negedge Clk) begin
237 
            Sys_clk = 1'b0;
238 
        end
239 
    end
240 
 
241 
    always @ (posedge Sys_clk) begin
242 
        // Internal Commamd Pipelined
243 
        Command[0] = Command[1];
244 
        Command[1] = Command[2];
245 
        Command[2] = Command[3];
246 
        Command[3] = `NOP;
247 
 
248 
        Col_addr[0] = Col_addr[1];
249 
        Col_addr[1] = Col_addr[2];
250 
        Col_addr[2] = Col_addr[3];
251 
        Col_addr[3] = {col_bits{1'b0}};
252 
 
253 
        Bank_addr[0] = Bank_addr[1];
254 
        Bank_addr[1] = Bank_addr[2];
255 
        Bank_addr[2] = Bank_addr[3];
256 
        Bank_addr[3] = 2'b0;
257 
 
258 
        Bank_precharge[0] = Bank_precharge[1];
259 
        Bank_precharge[1] = Bank_precharge[2];
260 
        Bank_precharge[2] = Bank_precharge[3];
261 
        Bank_precharge[3] = 2'b0;
262 
 
263 
        A10_precharge[0] = A10_precharge[1];
264 
        A10_precharge[1] = A10_precharge[2];
265 
        A10_precharge[2] = A10_precharge[3];
266 
        A10_precharge[3] = 1'b0;
267 
 
268 
        // Dqm pipeline for Read
269 
        Dqm_reg0 = Dqm_reg1;
270 
        Dqm_reg1 = Dqm;
271 
 
272 
        // Read or Write with Auto Precharge Counter
273 
        if (Auto_precharge[0] === 1'b1) begin
274 
            Count_precharge[0] = Count_precharge[0] + 1;
275 
        end
276 
        if (Auto_precharge[1] === 1'b1) begin
277 
            Count_precharge[1] = Count_precharge[1] + 1;
278 
        end
279 
        if (Auto_precharge[2] === 1'b1) begin
280 
            Count_precharge[2] = Count_precharge[2] + 1;
281 
        end
282 
        if (Auto_precharge[3] === 1'b1) begin
283 
            Count_precharge[3] = Count_precharge[3] + 1;
284 
        end
285 
 
286 
        // Read or Write Interrupt Counter
287 
        if (RW_interrupt_write[0] === 1'b1) begin
288 
            RW_interrupt_counter[0] = RW_interrupt_counter[0] + 1;
289 
        end
290 
        if (RW_interrupt_write[1] === 1'b1) begin
291 
            RW_interrupt_counter[1] = RW_interrupt_counter[1] + 1;
292 
        end
293 
        if (RW_interrupt_write[2] === 1'b1) begin
294 
            RW_interrupt_counter[2] = RW_interrupt_counter[2] + 1;
295 
        end
296 
        if (RW_interrupt_write[3] === 1'b1) begin
297 
            RW_interrupt_counter[3] = RW_interrupt_counter[3] + 1;
298 
        end
299 
 
300 
        // tMRD Counter
301 
        MRD_chk = MRD_chk + 1;
302 
 
303 
        // Auto Refresh
304 
        if (Aref_enable === 1'b1) begin
305 
            if (Debug) begin
306 
                $display ("%m : at time %t AREF : Auto Refresh", $time);
307 
            end
308 
 
309 
            // Auto Refresh to Auto Refresh
310 
            if ($time - RFC_chk < tRFC) begin
311 
                $display ("%m : at time %t ERROR: tRFC violation during Auto Refresh", $time);
312 
            end
313 
 
314 
            // Precharge to Auto Refresh
315 
            if (($time - RP_chk0 < tRP) || ($time - RP_chk1 < tRP) ||
316 
                ($time - RP_chk2 < tRP) || ($time - RP_chk3 < tRP)) begin
317 
                $display ("%m : at time %t ERROR: tRP violation during Auto Refresh", $time);
318 
            end
319 
 
320 
            // Precharge to Refresh
321 
            if (Pc_b0 === 1'b0 || Pc_b1 === 1'b0 || Pc_b2 === 1'b0 || Pc_b3 === 1'b0) begin
322 
                $display ("%m : at time %t ERROR: All banks must be Precharge before Auto Refresh", $time);
323 
            end
324 
 
325 
            // Load Mode Register to Auto Refresh
326 
            if (MRD_chk < tMRD) begin
327 
                $display ("%m : at time %t ERROR: tMRD violation during Auto Refresh", $time);
328 
            end
329 
 
330 
            // Record Current tRFC time
331 
            RFC_chk = $time;
332 
        end
333 
 
334 
        // Load Mode Register
335 
        if (Mode_reg_enable === 1'b1) begin
336 
            // Register Mode
337 
            Mode_reg = Addr;
338 
 
339 
            // Decode CAS Latency, Burst Length, Burst Type, and Write Burst Mode
340 
            if (Debug) begin
341 
                $display ("%m : at time %t LMR  : Load Mode Register", $time);
342 
                // CAS Latency
343 
                case (Addr[6 : 4])
344 
                    3'b010  : $display ("%m :                             CAS Latency      = 2");
345 
                    3'b011  : $display ("%m :                             CAS Latency      = 3");
346 
                    default : $display ("%m :                             CAS Latency      = Reserved");
347 
                endcase
348 
 
349 
                // Burst Length
350 
                case (Addr[2 : 0])
351 
                    3'b000  : $display ("%m :                             Burst Length     = 1");
352 
                    3'b001  : $display ("%m :                             Burst Length     = 2");
353 
                    3'b010  : $display ("%m :                             Burst Length     = 4");
354 
                    3'b011  : $display ("%m :                             Burst Length     = 8");
355 
                    3'b111  : $display ("%m :                             Burst Length     = Full");
356 
                    default : $display ("%m :                             Burst Length     = Reserved");
357 
                endcase
358 
 
359 
                // Burst Type
360 
                if (Addr[3] === 1'b0) begin
361 
                    $display ("%m :                             Burst Type       = Sequential");
362 
                end else if (Addr[3] === 1'b1) begin
363 
                    $display ("%m :                             Burst Type       = Interleaved");
364 
                end else begin
365 
                    $display ("%m :                             Burst Type       = Reserved");
366 
                end
367 
 
368 
                // Write Burst Mode
369 
                if (Addr[9] === 1'b0) begin
370 
                    $display ("%m :                             Write Burst Mode = Programmed Burst Length");
371 
                end else if (Addr[9] === 1'b1) begin
372 
                    $display ("%m :                             Write Burst Mode = Single Location Access");
373 
                end else begin
374 
                    $display ("%m :                             Write Burst Mode = Reserved");
375 
                end
376 
            end
377 
 
378 
            // Precharge to Load Mode Register
379 
            if (Pc_b0 === 1'b0 && Pc_b1 === 1'b0 && Pc_b2 === 1'b0 && Pc_b3 === 1'b0) begin
380 
                $display ("%m : at time %t ERROR: all banks must be Precharge before Load Mode Register", $time);
381 
            end
382 
 
383 
            // Precharge to Load Mode Register
384 
            if (($time - RP_chk0 < tRP) || ($time - RP_chk1 < tRP) ||
385 
                ($time - RP_chk2 < tRP) || ($time - RP_chk3 < tRP)) begin
386 
                $display ("%m : at time %t ERROR: tRP violation during Load Mode Register", $time);
387 
            end
388 
 
389 
            // Auto Refresh to Load Mode Register
390 
            if ($time - RFC_chk < tRFC) begin
391 
                $display ("%m : at time %t ERROR: tRFC violation during Load Mode Register", $time);
392 
            end
393 
 
394 
            // Load Mode Register to Load Mode Register
395 
            if (MRD_chk < tMRD) begin
396 
                $display ("%m : at time %t ERROR: tMRD violation during Load Mode Register", $time);
397 
            end
398 
 
399 
            // Reset MRD Counter
400 
            MRD_chk = 0;
401 
        end
402 
 
403 
        // Active Block (Latch Bank Address and Row Address)
404 
        if (Active_enable === 1'b1) begin
405 
            // Activate an open bank can corrupt data
406 
            if ((Ba === 2'b00 && Act_b0 === 1'b1) || (Ba === 2'b01 && Act_b1 === 1'b1) ||
407 
                (Ba === 2'b10 && Act_b2 === 1'b1) || (Ba === 2'b11 && Act_b3 === 1'b1)) begin
408 
                $display ("%m : at time %t ERROR: Bank already activated -- data can be corrupted", $time);
409 
            end
410 
 
411 
            // Activate Bank 0
412 
            if (Ba === 2'b00 && Pc_b0 === 1'b1) begin
413 
                // Debug Message
414 
                if (Debug) begin
415 
                    $display ("%m : at time %t ACT  : Bank = 0 Row = %h", $time, Addr);
416 
                end
417 
 
418 
                // ACTIVE to ACTIVE command period
419 
                if ($time - RC_chk0 < tRC) begin
420 
                    $display ("%m : at time %t ERROR: tRC violation during Activate bank 0", $time);
421 
                end
422 
 
423 
                // Precharge to Activate Bank 0
424 
                if ($time - RP_chk0 < tRP) begin
425 
                    $display ("%m : at time %t ERROR: tRP violation during Activate bank 0", $time);
426 
                end
427 
 
428 
                // Record variables
429 
                Act_b0 = 1'b1;
430 
                Pc_b0 = 1'b0;
431 
                B0_row_addr = Addr [addr_bits - 1 : 0];
432 
                RAS_chk0 = $time;
433 
                RC_chk0 = $time;
434 
                RCD_chk0 = $time;
435 
            end
436 
 
437 
            if (Ba == 2'b01 && Pc_b1 == 1'b1) begin
438 
                // Debug Message
439 
                if (Debug) begin
440 
                    $display ("%m : at time %t ACT  : Bank = 1 Row = %h", $time, Addr);
441 
                end
442 
 
443 
                // ACTIVE to ACTIVE command period
444 
                if ($time - RC_chk1 < tRC) begin
445 
                    $display ("%m : at time %t ERROR: tRC violation during Activate bank 1", $time);
446 
                end
447 
 
448 
                // Precharge to Activate Bank 1
449 
                if ($time - RP_chk1 < tRP) begin
450 
                    $display ("%m : at time %t ERROR: tRP violation during Activate bank 1", $time);
451 
                end
452 
 
453 
                // Record variables
454 
                Act_b1 = 1'b1;
455 
                Pc_b1 = 1'b0;
456 
                B1_row_addr = Addr [addr_bits - 1 : 0];
457 
                RAS_chk1 = $time;
458 
                RC_chk1 = $time;
459 
                RCD_chk1 = $time;
460 
            end
461 
 
462 
            if (Ba == 2'b10 && Pc_b2 == 1'b1) begin
463 
                // Debug Message
464 
                if (Debug) begin
465 
                    $display ("%m : at time %t ACT  : Bank = 2 Row = %h", $time, Addr);
466 
                end
467 
 
468 
                // ACTIVE to ACTIVE command period
469 
                if ($time - RC_chk2 < tRC) begin
470 
                    $display ("%m : at time %t ERROR: tRC violation during Activate bank 2", $time);
471 
                end
472 
 
473 
                // Precharge to Activate Bank 2
474 
                if ($time - RP_chk2 < tRP) begin
475 
                    $display ("%m : at time %t ERROR: tRP violation during Activate bank 2", $time);
476 
                end
477 
 
478 
                // Record variables
479 
                Act_b2 = 1'b1;
480 
                Pc_b2 = 1'b0;
481 
                B2_row_addr = Addr [addr_bits - 1 : 0];
482 
                RAS_chk2 = $time;
483 
                RC_chk2 = $time;
484 
                RCD_chk2 = $time;
485 
            end
486 
 
487 
            if (Ba == 2'b11 && Pc_b3 == 1'b1) begin
488 
                // Debug Message
489 
                if (Debug) begin
490 
                    $display ("%m : at time %t ACT  : Bank = 3 Row = %h", $time, Addr);
491 
                end
492 
 
493 
                // ACTIVE to ACTIVE command period
494 
                if ($time - RC_chk3 < tRC) begin
495 
                    $display ("%m : at time %t ERROR: tRC violation during Activate bank 3", $time);
496 
                end
497 
 
498 
                // Precharge to Activate Bank 3
499 
                if ($time - RP_chk3 < tRP) begin
500 
                    $display ("%m : at time %t ERROR: tRP violation during Activate bank 3", $time);
501 
                end
502 
 
503 
                // Record variables
504 
                Act_b3 = 1'b1;
505 
                Pc_b3 = 1'b0;
506 
                B3_row_addr = Addr [addr_bits - 1 : 0];
507 
                RAS_chk3 = $time;
508 
                RC_chk3 = $time;
509 
                RCD_chk3 = $time;
510 
            end
511 
 
512 
            // Active Bank A to Active Bank B
513 
            if ((Prev_bank != Ba) && ($time - RRD_chk < tRRD)) begin
514 
                $display ("%m : at time %t ERROR: tRRD violation during Activate bank = %h", $time, Ba);
515 
            end
516 
 
517 
            // Auto Refresh to Activate
518 
            if ($time - RFC_chk < tRFC) begin
519 
                $display ("%m : at time %t ERROR: tRFC violation during Activate bank = %h", $time, Ba);
520 
            end
521 
 
522 
            // Load Mode Register to Active
523 
            if (MRD_chk < tMRD ) begin
524 
                $display ("%m : at time %t ERROR: tMRD violation during Activate bank = %h", $time, Ba);
525 
            end
526 
 
527 
            // Record variables for checking violation
528 
            RRD_chk = $time;
529 
            Prev_bank = Ba;
530 
        end
531 
 
532 
        // Precharge Block
533 
        if (Prech_enable == 1'b1) begin
534 
            // Load Mode Register to Precharge
535 
            if ($time - MRD_chk < tMRD) begin
536 
                $display ("%m : at time %t ERROR: tMRD violaiton during Precharge", $time);
537 
            end
538 
 
539 
            // Precharge Bank 0
540 
            if ((Addr[10] === 1'b1 || (Addr[10] === 1'b0 && Ba === 2'b00)) && Act_b0 === 1'b1) begin
541 
                Act_b0 = 1'b0;
542 
                Pc_b0 = 1'b1;
543 
                RP_chk0 = $time;
544 
 
545 
                // Activate to Precharge
546 
                if ($time - RAS_chk0 < tRAS) begin
547 
                    $display ("%m : at time %t ERROR: tRAS violation during Precharge", $time);
548 
                end
549 
 
550 
                // tWR violation check for write
551 
                if ($time - WR_chkm[0] < tWRm) begin
552 
                    $display ("%m : at time %t ERROR: tWR violation during Precharge", $time);
553 
                end
554 
            end
555 
 
556 
            // Precharge Bank 1
557 
            if ((Addr[10] === 1'b1 || (Addr[10] === 1'b0 && Ba === 2'b01)) && Act_b1 === 1'b1) begin
558 
                Act_b1 = 1'b0;
559 
                Pc_b1 = 1'b1;
560 
                RP_chk1 = $time;
561 
 
562 
                // Activate to Precharge
563 
                if ($time - RAS_chk1 < tRAS) begin
564 
                    $display ("%m : at time %t ERROR: tRAS violation during Precharge", $time);
565 
                end
566 
 
567 
                // tWR violation check for write
568 
                if ($time - WR_chkm[1] < tWRm) begin
569 
                    $display ("%m : at time %t ERROR: tWR violation during Precharge", $time);
570 
                end
571 
            end
572 
 
573 
            // Precharge Bank 2
574 
            if ((Addr[10] === 1'b1 || (Addr[10] === 1'b0 && Ba === 2'b10)) && Act_b2 === 1'b1) begin
575 
                Act_b2 = 1'b0;
576 
                Pc_b2 = 1'b1;
577 
                RP_chk2 = $time;
578 
 
579 
                // Activate to Precharge
580 
                if ($time - RAS_chk2 < tRAS) begin
581 
                    $display ("%m : at time %t ERROR: tRAS violation during Precharge", $time);
582 
                end
583 
 
584 
                // tWR violation check for write
585 
                if ($time - WR_chkm[2] < tWRm) begin
586 
                    $display ("%m : at time %t ERROR: tWR violation during Precharge", $time);
587 
                end
588 
            end
589 
 
590 
            // Precharge Bank 3
591 
            if ((Addr[10] === 1'b1 || (Addr[10] === 1'b0 && Ba === 2'b11)) && Act_b3 === 1'b1) begin
592 
                Act_b3 = 1'b0;
593 
                Pc_b3 = 1'b1;
594 
                RP_chk3 = $time;
595 
 
596 
                // Activate to Precharge
597 
                if ($time - RAS_chk3 < tRAS) begin
598 
                    $display ("%m : at time %t ERROR: tRAS violation during Precharge", $time);
599 
                end
600 
 
601 
                // tWR violation check for write
602 
                if ($time - WR_chkm[3] < tWRm) begin
603 
                    $display ("%m : at time %t ERROR: tWR violation during Precharge", $time);
604 
                end
605 
            end
606 
 
607 
            // Terminate a Write Immediately (if same bank or all banks)
608 
            if (Data_in_enable === 1'b1 && (Bank === Ba || Addr[10] === 1'b1)) begin
609 
                Data_in_enable = 1'b0;
610 
            end
611 
 
612 
            // Precharge Command Pipeline for Read
613 
            if (Cas_latency_3 === 1'b1) begin
614 
                Command[2] = `PRECH;
615 
                Bank_precharge[2] = Ba;
616 
                A10_precharge[2] = Addr[10];
617 
            end else if (Cas_latency_2 === 1'b1) begin
618 
                Command[1] = `PRECH;
619 
                Bank_precharge[1] = Ba;
620 
                A10_precharge[1] = Addr[10];
621 
            end
622 
        end
623 
 
624 
        // Burst terminate
625 
        if (Burst_term === 1'b1) begin
626 
            // Terminate a Write Immediately
627 
            if (Data_in_enable == 1'b1) begin
628 
                Data_in_enable = 1'b0;
629 
            end
630 
 
631 
            // Terminate a Read Depend on CAS Latency
632 
            if (Cas_latency_3 === 1'b1) begin
633 
                Command[2] = `BST;
634 
            end else if (Cas_latency_2 == 1'b1) begin
635 
                Command[1] = `BST;
636 
            end
637 
 
638 
            // Display debug message
639 
            if (Debug) begin
640 
                $display ("%m : at time %t BST  : Burst Terminate",$time);
641 
            end
642 
        end
643 
 
644 
        // Read, Write, Column Latch
645 
        if (Read_enable === 1'b1) begin
646 
            // Check to see if bank is open (ACT)
647 
            if ((Ba == 2'b00 && Pc_b0 == 1'b1) || (Ba == 2'b01 && Pc_b1 == 1'b1) ||
648 
                (Ba == 2'b10 && Pc_b2 == 1'b1) || (Ba == 2'b11 && Pc_b3 == 1'b1)) begin
649 
                $display("%m : at time %t ERROR: Bank is not Activated for Read", $time);
650 
            end
651 
 
652 
            // Activate to Read or Write
653 
            if ((Ba == 2'b00) && ($time - RCD_chk0 < tRCD) ||
654 
                (Ba == 2'b01) && ($time - RCD_chk1 < tRCD) ||
655 
                (Ba == 2'b10) && ($time - RCD_chk2 < tRCD) ||
656 
                (Ba == 2'b11) && ($time - RCD_chk3 < tRCD)) begin
657 
                $display("%m : at time %t ERROR: tRCD violation during Read", $time);
658 
            end
659 
 
660 
            // CAS Latency pipeline
661 
            if (Cas_latency_3 == 1'b1) begin
662 
                Command[2] = `READ;
663 
                Col_addr[2] = Addr;
664 
                Bank_addr[2] = Ba;
665 
            end else if (Cas_latency_2 == 1'b1) begin
666 
                Command[1] = `READ;
667 
                Col_addr[1] = Addr;
668 
                Bank_addr[1] = Ba;
669 
            end
670 
 
671 
            // Read interrupt Write (terminate Write immediately)
672 
            if (Data_in_enable == 1'b1) begin
673 
                Data_in_enable = 1'b0;
674 
 
675 
                // Interrupting a Write with Autoprecharge
676 
                if (Auto_precharge[RW_interrupt_bank] == 1'b1 && Write_precharge[RW_interrupt_bank] == 1'b1) begin
677 
                    RW_interrupt_write[RW_interrupt_bank] = 1'b1;
678 
                    RW_interrupt_counter[RW_interrupt_bank] = 0;
679 
 
680 
                    // Display debug message
681 
                    if (Debug) begin
682 
                        $display ("%m : at time %t NOTE : Read interrupt Write with Autoprecharge", $time);
683 
                    end
684 
                end
685 
            end
686 
 
687 
            // Write with Auto Precharge
688 
            if (Addr[10] == 1'b1) begin
689 
                Auto_precharge[Ba] = 1'b1;
690 
                Count_precharge[Ba] = 0;
691 
                RW_interrupt_bank = Ba;
692 
                Read_precharge[Ba] = 1'b1;
693 
            end
694 
        end
695 
 
696 
        // Write Command
697 
        if (Write_enable == 1'b1) begin
698 
            // Activate to Write
699 
            if ((Ba == 2'b00 && Pc_b0 == 1'b1) || (Ba == 2'b01 && Pc_b1 == 1'b1) ||
700 
                (Ba == 2'b10 && Pc_b2 == 1'b1) || (Ba == 2'b11 && Pc_b3 == 1'b1)) begin
701 
                $display("%m : at time %t ERROR: Bank is not Activated for Write", $time);
702 
            end
703 
 
704 
            // Activate to Read or Write
705 
            if ((Ba == 2'b00) && ($time - RCD_chk0 < tRCD) ||
706 
                (Ba == 2'b01) && ($time - RCD_chk1 < tRCD) ||
707 
                (Ba == 2'b10) && ($time - RCD_chk2 < tRCD) ||
708 
                (Ba == 2'b11) && ($time - RCD_chk3 < tRCD)) begin
709 
                $display("%m : at time %t ERROR: tRCD violation during Read", $time);
710 
            end
711 
 
712 
            // Latch Write command, Bank, and Column
713 
            Command[0] = `WRITE;
714 
            Col_addr[0] = Addr;
715 
            Bank_addr[0] = Ba;
716 
 
717 
            // Write interrupt Write (terminate Write immediately)
718 
            if (Data_in_enable == 1'b1) begin
719 
                Data_in_enable = 1'b0;
720 
 
721 
                // Interrupting a Write with Autoprecharge
722 
                if (Auto_precharge[RW_interrupt_bank] == 1'b1 && Write_precharge[RW_interrupt_bank] == 1'b1) begin
723 
                    RW_interrupt_write[RW_interrupt_bank] = 1'b1;
724 
 
725 
                    // Display debug message
726 
                    if (Debug) begin
727 
                        $display ("%m : at time %t NOTE : Read Bank %h interrupt Write Bank %h with Autoprecharge", $time, Ba, RW_interrupt_bank);
728 
                    end
729 
                end
730 
            end
731 
 
732 
            // Write interrupt Read (terminate Read immediately)
733 
            if (Data_out_enable == 1'b1) begin
734 
                Data_out_enable = 1'b0;
735 
 
736 
                // Interrupting a Read with Autoprecharge
737 
                if (Auto_precharge[RW_interrupt_bank] == 1'b1 && Read_precharge[RW_interrupt_bank] == 1'b1) begin
738 
                    RW_interrupt_read[RW_interrupt_bank] = 1'b1;
739 
 
740 
                    // Display debug message
741 
                    if (Debug) begin
742 
                        $display ("%m : at time %t NOTE : Write Bank %h interrupt Read Bank %h with Autoprecharge", $time, Ba, RW_interrupt_bank);
743 
                    end
744 
                end
745 
            end
746 
 
747 
            // Write with Auto Precharge
748 
            if (Addr[10] == 1'b1) begin
749 
                Auto_precharge[Ba] = 1'b1;
750 
                Count_precharge[Ba] = 0;
751 
                RW_interrupt_bank = Ba;
752 
                Write_precharge[Ba] = 1'b1;
753 
            end
754 
        end
755 
 
756 
        /*
757 
            Write with Auto Precharge Calculation
758 
                The device start internal precharge when:
759 
                    1.  Meet minimum tRAS requirement
760 
                and 2.  tWR cycle(s) after last valid data
761 
                 or 3.  Interrupt by a Read or Write (with or without Auto Precharge)
762 
 
763 
            Note: Model is starting the internal precharge 1 cycle after they meet all the
764 
                  requirement but tRP will be compensate for the time after the 1 cycle.
765 
        */
766 
        if ((Auto_precharge[0] == 1'b1) && (Write_precharge[0] == 1'b1)) begin
767 
            if ((($time - RAS_chk0 >= tRAS) &&                                                          // Case 1
768 
               (((Burst_length_1 == 1'b1 || Write_burst_mode == 1'b1) && Count_precharge [0] >= 1) ||   // Case 2
769 
                 (Burst_length_2 == 1'b1                              && Count_precharge [0] >= 2) ||
770 
                 (Burst_length_4 == 1'b1                              && Count_precharge [0] >= 4) ||
771 
                 (Burst_length_8 == 1'b1                              && Count_precharge [0] >= 8))) ||
772 
                 (RW_interrupt_write[0] == 1'b1 && RW_interrupt_counter[0] >= 1)) begin                 // Case 3
773 
                    Auto_precharge[0] = 1'b0;
774 
                    Write_precharge[0] = 1'b0;
775 
                    RW_interrupt_write[0] = 1'b0;
776 
                    Pc_b0 = 1'b1;
777 
                    Act_b0 = 1'b0;
778 
                    RP_chk0 = $time + tWRa;
779 
                    if (Debug) begin
780 
                        $display ("%m : at time %t NOTE : Start Internal Auto Precharge for Bank 0", $time);
781 
                    end
782 
            end
783 
        end
784 
        if ((Auto_precharge[1] == 1'b1) && (Write_precharge[1] == 1'b1)) begin
785 
            if ((($time - RAS_chk1 >= tRAS) &&                                                          // Case 1
786 
               (((Burst_length_1 == 1'b1 || Write_burst_mode == 1'b1) && Count_precharge [1] >= 1) ||   // Case 2
787 
                 (Burst_length_2 == 1'b1                              && Count_precharge [1] >= 2) ||
788 
                 (Burst_length_4 == 1'b1                              && Count_precharge [1] >= 4) ||
789 
                 (Burst_length_8 == 1'b1                              && Count_precharge [1] >= 8))) ||
790 
                 (RW_interrupt_write[1] == 1'b1 && RW_interrupt_counter[1] >= 1)) begin                 // Case 3
791 
                    Auto_precharge[1] = 1'b0;
792 
                    Write_precharge[1] = 1'b0;
793 
                    RW_interrupt_write[1] = 1'b0;
794 
                    Pc_b1 = 1'b1;
795 
                    Act_b1 = 1'b0;
796 
                    RP_chk1 = $time + tWRa;
797 
                    if (Debug) begin
798 
                        $display ("%m : at time %t NOTE : Start Internal Auto Precharge for Bank 1", $time);
799 
                    end
800 
            end
801 
        end
802 
        if ((Auto_precharge[2] == 1'b1) && (Write_precharge[2] == 1'b1)) begin
803 
            if ((($time - RAS_chk2 >= tRAS) &&                                                          // Case 1
804 
               (((Burst_length_1 == 1'b1 || Write_burst_mode == 1'b1) && Count_precharge [2] >= 1) ||   // Case 2
805 
                 (Burst_length_2 == 1'b1                              && Count_precharge [2] >= 2) ||
806 
                 (Burst_length_4 == 1'b1                              && Count_precharge [2] >= 4) ||
807 
                 (Burst_length_8 == 1'b1                              && Count_precharge [2] >= 8))) ||
808 
                 (RW_interrupt_write[2] == 1'b1 && RW_interrupt_counter[2] >= 1)) begin                 // Case 3
809 
                    Auto_precharge[2] = 1'b0;
810 
                    Write_precharge[2] = 1'b0;
811 
                    RW_interrupt_write[2] = 1'b0;
812 
                    Pc_b2 = 1'b1;
813 
                    Act_b2 = 1'b0;
814 
                    RP_chk2 = $time + tWRa;
815 
                    if (Debug) begin
816 
                        $display ("%m : at time %t NOTE : Start Internal Auto Precharge for Bank 2", $time);
817 
                    end
818 
            end
819 
        end
820 
        if ((Auto_precharge[3] == 1'b1) && (Write_precharge[3] == 1'b1)) begin
821 
            if ((($time - RAS_chk3 >= tRAS) &&                                                          // Case 1
822 
               (((Burst_length_1 == 1'b1 || Write_burst_mode == 1'b1) && Count_precharge [3] >= 1) ||   // Case 2
823 
                 (Burst_length_2 == 1'b1                              && Count_precharge [3] >= 2) ||
824 
                 (Burst_length_4 == 1'b1                              && Count_precharge [3] >= 4) ||
825 
                 (Burst_length_8 == 1'b1                              && Count_precharge [3] >= 8))) ||
826 
                 (RW_interrupt_write[3] == 1'b1 && RW_interrupt_counter[3] >= 1)) begin                 // Case 3
827 
                    Auto_precharge[3] = 1'b0;
828 
                    Write_precharge[3] = 1'b0;
829 
                    RW_interrupt_write[3] = 1'b0;
830 
                    Pc_b3 = 1'b1;
831 
                    Act_b3 = 1'b0;
832 
                    RP_chk3 = $time + tWRa;
833 
                    if (Debug) begin
834 
                        $display ("%m : at time %t NOTE : Start Internal Auto Precharge for Bank 3", $time);
835 
                    end
836 
            end
837 
        end
838 
 
839 
        //  Read with Auto Precharge Calculation
840 
        //      The device start internal precharge:
841 
        //          1.  Meet minimum tRAS requirement
842 
        //      and 2.  CAS Latency - 1 cycles before last burst
843 
        //       or 3.  Interrupt by a Read or Write (with or without AutoPrecharge)
844 
        if ((Auto_precharge[0] == 1'b1) && (Read_precharge[0] == 1'b1)) begin
845 
            if ((($time - RAS_chk0 >= tRAS) &&                                                      // Case 1
846 
                ((Burst_length_1 == 1'b1 && Count_precharge[0] >= 1) ||                             // Case 2
847 
                 (Burst_length_2 == 1'b1 && Count_precharge[0] >= 2) ||
848 
                 (Burst_length_4 == 1'b1 && Count_precharge[0] >= 4) ||
849 
                 (Burst_length_8 == 1'b1 && Count_precharge[0] >= 8))) ||
850 
                 (RW_interrupt_read[0] == 1'b1)) begin                                              // Case 3
851 
                    Pc_b0 = 1'b1;
852 
                    Act_b0 = 1'b0;
853 
                    RP_chk0 = $time;
854 
                    Auto_precharge[0] = 1'b0;
855 
                    Read_precharge[0] = 1'b0;
856 
                    RW_interrupt_read[0] = 1'b0;
857 
                    if (Debug) begin
858 
                        $display ("%m : at time %t NOTE : Start Internal Auto Precharge for Bank 0", $time);
859 
                    end
860 
            end
861 
        end
862 
        if ((Auto_precharge[1] == 1'b1) && (Read_precharge[1] == 1'b1)) begin
863 
            if ((($time - RAS_chk1 >= tRAS) &&
864 
                ((Burst_length_1 == 1'b1 && Count_precharge[1] >= 1) ||
865 
                 (Burst_length_2 == 1'b1 && Count_precharge[1] >= 2) ||
866 
                 (Burst_length_4 == 1'b1 && Count_precharge[1] >= 4) ||
867 
                 (Burst_length_8 == 1'b1 && Count_precharge[1] >= 8))) ||
868 
                 (RW_interrupt_read[1] == 1'b1)) begin
869 
                    Pc_b1 = 1'b1;
870 
                    Act_b1 = 1'b0;
871 
                    RP_chk1 = $time;
872 
                    Auto_precharge[1] = 1'b0;
873 
                    Read_precharge[1] = 1'b0;
874 
                    RW_interrupt_read[1] = 1'b0;
875 
                    if (Debug) begin
876 
                        $display ("%m : at time %t NOTE : Start Internal Auto Precharge for Bank 1", $time);
877 
                    end
878 
            end
879 
        end
880 
        if ((Auto_precharge[2] == 1'b1) && (Read_precharge[2] == 1'b1)) begin
881 
            if ((($time - RAS_chk2 >= tRAS) &&
882 
                ((Burst_length_1 == 1'b1 && Count_precharge[2] >= 1) ||
883 
                 (Burst_length_2 == 1'b1 && Count_precharge[2] >= 2) ||
884 
                 (Burst_length_4 == 1'b1 && Count_precharge[2] >= 4) ||
885 
                 (Burst_length_8 == 1'b1 && Count_precharge[2] >= 8))) ||
886 
                 (RW_interrupt_read[2] == 1'b1)) begin
887 
                    Pc_b2 = 1'b1;
888 
                    Act_b2 = 1'b0;
889 
                    RP_chk2 = $time;
890 
                    Auto_precharge[2] = 1'b0;
891 
                    Read_precharge[2] = 1'b0;
892 
                    RW_interrupt_read[2] = 1'b0;
893 
                    if (Debug) begin
894 
                        $display ("%m : at time %t NOTE : Start Internal Auto Precharge for Bank 2", $time);
895 
                    end
896 
            end
897 
        end
898 
        if ((Auto_precharge[3] == 1'b1) && (Read_precharge[3] == 1'b1)) begin
899 
            if ((($time - RAS_chk3 >= tRAS) &&
900 
                ((Burst_length_1 == 1'b1 && Count_precharge[3] >= 1) ||
901 
                 (Burst_length_2 == 1'b1 && Count_precharge[3] >= 2) ||
902 
                 (Burst_length_4 == 1'b1 && Count_precharge[3] >= 4) ||
903 
                 (Burst_length_8 == 1'b1 && Count_precharge[3] >= 8))) ||
904 
                 (RW_interrupt_read[3] == 1'b1)) begin
905 
                    Pc_b3 = 1'b1;
906 
                    Act_b3 = 1'b0;
907 
                    RP_chk3 = $time;
908 
                    Auto_precharge[3] = 1'b0;
909 
                    Read_precharge[3] = 1'b0;
910 
                    RW_interrupt_read[3] = 1'b0;
911 
                    if (Debug) begin
912 
                        $display("%m : at time %t NOTE : Start Internal Auto Precharge for Bank 3", $time);
913 
                    end
914 
            end
915 
        end
916 
 
917 
        // Internal Precharge or Bst
918 
        if (Command[0] == `PRECH) begin                         // Precharge terminate a read with same bank or all banks
919 
            if (Bank_precharge[0] == Bank || A10_precharge[0] == 1'b1) begin
920 
                if (Data_out_enable == 1'b1) begin
921 
                    Data_out_enable = 1'b0;
922 
                end
923 
            end
924 
        end else if (Command[0] == `BST) begin                  // BST terminate a read to current bank
925 
            if (Data_out_enable == 1'b1) begin
926 
                Data_out_enable = 1'b0;
927 
            end
928 
        end
929 
 
930 
        if (Data_out_enable == 1'b0) begin
931 
            Dq_reg <= #tOH {data_bits{1'bz}};
932 
        end
933 
 
934 
        // Detect Read or Write command
935 
        if (Command[0] == `READ) begin
936 
            Bank = Bank_addr[0];
937 
            Col = Col_addr[0];
938 
            Col_brst = Col_addr[0];
939 
            case (Bank_addr[0])
940 
                2'b00 : Row = B0_row_addr;
941 
                2'b01 : Row = B1_row_addr;
942 
                2'b10 : Row = B2_row_addr;
943 
                2'b11 : Row = B3_row_addr;
944 
            endcase
945 
            Burst_counter = 0;
946 
            Data_in_enable = 1'b0;
947 
            Data_out_enable = 1'b1;
948 
        end else if (Command[0] == `WRITE) begin
949 
            Bank = Bank_addr[0];
950 
            Col = Col_addr[0];
951 
            Col_brst = Col_addr[0];
952 
            case (Bank_addr[0])
953 
                2'b00 : Row = B0_row_addr;
954 
                2'b01 : Row = B1_row_addr;
955 
                2'b10 : Row = B2_row_addr;
956 
                2'b11 : Row = B3_row_addr;
957 
            endcase
958 
            Burst_counter = 0;
959 
            Data_in_enable = 1'b1;
960 
            Data_out_enable = 1'b0;
961 
        end
962 
 
963 
        // DQ buffer (Driver/Receiver)
964 
        if (Data_in_enable == 1'b1) begin                                   // Writing Data to Memory
965 
            // Array buffer
966 
            case (Bank)
967 
                2'b00 : Dq_dqm = Bank0 [{Row, Col}];
968 
                2'b01 : Dq_dqm = Bank1 [{Row, Col}];
969 
                2'b10 : Dq_dqm = Bank2 [{Row, Col}];
970 
                2'b11 : Dq_dqm = Bank3 [{Row, Col}];
971 
            endcase
972 
 
973 
            // Dqm operation
974 
            if (Dqm[0] == 1'b0) begin
975 
                Dq_dqm [ 7 : 0] = Dq [ 7 : 0];
976 
            end
977 
            if (Dqm[1] == 1'b0) begin
978 
                Dq_dqm [15 : 8] = Dq [15 : 8];
979 
            end
980 
 
981 
            // Write to memory
982 
            case (Bank)
983 
                2'b00 : Bank0 [{Row, Col}] = Dq_dqm;
984 
                2'b01 : Bank1 [{Row, Col}] = Dq_dqm;
985 
                2'b10 : Bank2 [{Row, Col}] = Dq_dqm;
986 
                2'b11 : Bank3 [{Row, Col}] = Dq_dqm;
987 
            endcase
988 
 
989 
            // Display debug message
990 
            if (Dqm !== 2'b11) begin
991 
                // Record tWR for manual precharge
992 
                WR_chkm [Bank] = $time;
993 
 
994 
                if (Debug) begin
995 
                    $display("%m : at time %t WRITE: Bank = %h Row = %h, Col = %h, Data = %h", $time, Bank, Row, Col, Dq_dqm);
996 
                end
997 
            end else begin
998 
                if (Debug) begin
999 
                    $display("%m : at time %t WRITE: Bank = %h Row = %h, Col = %h, Data = Hi-Z due to DQM", $time, Bank, Row, Col);
1000 
                end
1001 
            end
1002 
 
1003 
            // Advance burst counter subroutine
1004 
            #tHZ Burst_decode;
1005 
 
1006 
        end else if (Data_out_enable == 1'b1) begin                         // Reading Data from Memory
1007 
            // Array buffer
1008 
            case (Bank)
1009 
                2'b00 : Dq_dqm = Bank0[{Row, Col}];
1010 
                2'b01 : Dq_dqm = Bank1[{Row, Col}];
1011 
                2'b10 : Dq_dqm = Bank2[{Row, Col}];
1012 
                2'b11 : Dq_dqm = Bank3[{Row, Col}];
1013 
            endcase
1014 
 
1015 
            // Dqm operation
1016 
            if (Dqm_reg0 [0] == 1'b1) begin
1017 
                Dq_dqm [ 7 : 0] = 8'bz;
1018 
            end
1019 
            if (Dqm_reg0 [1] == 1'b1) begin
1020 
                Dq_dqm [15 : 8] = 8'bz;
1021 
            end
1022 
 
1023 
            // Display debug message
1024 
            if (Dqm_reg0 !== 2'b11) begin
1025 
                Dq_reg = #tAC Dq_dqm;
1026 
                if (Debug) begin
1027 
                    $display("%m : at time %t READ : Bank = %h Row = %h, Col = %h, Data = %h", $time, Bank, Row, Col, Dq_reg);
1028 
                end
1029 
            end else begin
1030 
                Dq_reg = #tHZ {data_bits{1'bz}};
1031 
                if (Debug) begin
1032 
                    $display("%m : at time %t READ : Bank = %h Row = %h, Col = %h, Data = Hi-Z due to DQM", $time, Bank, Row, Col);
1033 
                end
1034 
            end
1035 
 
1036 
            // Advance burst counter subroutine
1037 
            Burst_decode;
1038 
        end
1039 
    end
1040 
 
1041 
    // Burst counter decode
1042 
    task Burst_decode;
1043 
        begin
1044 
            // Advance Burst Counter
1045 
            Burst_counter = Burst_counter + 1;
1046 
 
1047 
            // Burst Type
1048 
            if (Mode_reg[3] == 1'b0) begin                                  // Sequential Burst
1049 
                Col_temp = Col + 1;
1050 
            end else if (Mode_reg[3] == 1'b1) begin                         // Interleaved Burst
1051 
                Col_temp[2] =  Burst_counter[2] ^  Col_brst[2];
1052 
                Col_temp[1] =  Burst_counter[1] ^  Col_brst[1];
1053 
                Col_temp[0] =  Burst_counter[0] ^  Col_brst[0];
1054 
            end
1055 
 
1056 
            // Burst Length
1057 
            if (Burst_length_2) begin                                       // Burst Length = 2
1058 
                Col [0] = Col_temp [0];
1059 
            end else if (Burst_length_4) begin                              // Burst Length = 4
1060 
                Col [1 : 0] = Col_temp [1 : 0];
1061 
            end else if (Burst_length_8) begin                              // Burst Length = 8
1062 
                Col [2 : 0] = Col_temp [2 : 0];
1063 
            end else begin                                                  // Burst Length = FULL
1064 
                Col = Col_temp;
1065 
            end
1066 
 
1067 
            // Burst Read Single Write
1068 
            if (Write_burst_mode == 1'b1) begin
1069 
                Data_in_enable = 1'b0;
1070 
            end
1071 
 
1072 
            // Data Counter
1073 
            if (Burst_length_1 == 1'b1) begin
1074 
                if (Burst_counter >= 1) begin
1075 
                    Data_in_enable = 1'b0;
1076 
                    Data_out_enable = 1'b0;
1077 
                end
1078 
            end else if (Burst_length_2 == 1'b1) begin
1079 
                if (Burst_counter >= 2) begin
1080 
                    Data_in_enable = 1'b0;
1081 
                    Data_out_enable = 1'b0;
1082 
                end
1083 
            end else if (Burst_length_4 == 1'b1) begin
1084 
                if (Burst_counter >= 4) begin
1085 
                    Data_in_enable = 1'b0;
1086 
                    Data_out_enable = 1'b0;
1087 
                end
1088 
            end else if (Burst_length_8 == 1'b1) begin
1089 
                if (Burst_counter >= 8) begin
1090 
                    Data_in_enable = 1'b0;
1091 
                    Data_out_enable = 1'b0;
1092 
                end
1093 
            end
1094 
        end
1095 
    endtask
1096 
 
1097 
    // Timing Parameters for -7E (133 MHz @ CL2)
1098 
    specify
1099 
        specparam
1100 
            tAH  =  0.8,                                        // Addr, Ba Hold Time
1101 
            tAS  =  1.5,                                        // Addr, Ba Setup Time
1102 
            tCH  =  2.5,                                        // Clock High-Level Width
1103 
            tCL  =  2.5,                                        // Clock Low-Level Width
1104 
            tCK  =  7.0,                                        // Clock Cycle Time
1105 
            tDH  =  0.8,                                        // Data-in Hold Time
1106 
            tDS  =  1.5,                                        // Data-in Setup Time
1107 
            tCKH =  0.8,                                        // CKE Hold  Time
1108 
            tCKS =  1.5,                                        // CKE Setup Time
1109 
            tCMH =  0.8,                                        // CS#, RAS#, CAS#, WE#, DQM# Hold  Time
1110 
            tCMS =  1.5;                                        // CS#, RAS#, CAS#, WE#, DQM# Setup Time
1111 
        $width    (posedge Clk,           tCH);
1112 
        $width    (negedge Clk,           tCL);
1113 
        $period   (negedge Clk,           tCK);
1114 
        $period   (posedge Clk,           tCK);
1115 
        $setuphold(posedge Clk,    Cke,   tCKS, tCKH);
1116 
        $setuphold(posedge Clk,    Cs_n,  tCMS, tCMH);
1117 
        $setuphold(posedge Clk,    Cas_n, tCMS, tCMH);
1118 
        $setuphold(posedge Clk,    Ras_n, tCMS, tCMH);
1119 
        $setuphold(posedge Clk,    We_n,  tCMS, tCMH);
1120 
        $setuphold(posedge Clk,    Addr,  tAS,  tAH);
1121 
        $setuphold(posedge Clk,    Ba,    tAS,  tAH);
1122 
        $setuphold(posedge Clk,    Dqm,   tCMS, tCMH);
1123 
        $setuphold(posedge Dq_chk, Dq,    tDS,  tDH);
1124 
    endspecify
1125 
 
1126 403 julius 
   task get_byte;
1127 
      input [31:0] addr;
1128 
      output [7:0] data;
1129 
      reg [1:0]     bank;
1130 
      reg [15:0]   short;
1131 
 
1132 
      begin
1133 
         bank = addr[24:23];
1134 
 
1135 
         case(bank)
1136 
           2'b00:
1137 
             short = Bank0[addr[22:1]];
1138 
           2'b01:
1139 
             short = Bank1[addr[22:1]];
1140 
           2'b10:
1141 
             short = Bank2[addr[22:1]];
1142 
           2'b11:
1143 
             short = Bank3[addr[22:1]];
1144 
         endcase // case (bank)
1145 
 
1146 
         // Get the byte from the short
1147 
         if (!addr[0])
1148 
           data = short[15:8];
1149 
         else
1150 
           data = short[7:0];
1151 
 
1152 
         //$display("SDRAM addr 0x%0h, bank %0d, short 0x%0h, byte 0x%0h", addr, bank, short, data);
1153 495 julius 
      end
1154 
   endtask // get_byte
1155 
 
1156 
   task set_byte;
1157 
      input [31:0] addr;
1158 
      input [7:0] data;
1159 
      reg [1:0]     bank;
1160 
      reg [15:0]   short;
1161 
 
1162 
      begin
1163 
         bank = addr[24:23];
1164 403 julius 
 
1165 495 julius 
         case(bank)
1166 
           2'b00:
1167 
             short = Bank0[addr[22:1]];
1168 
           2'b01:
1169 
             short = Bank1[addr[22:1]];
1170 
           2'b10:
1171 
             short = Bank2[addr[22:1]];
1172 
           2'b11:
1173 
             short = Bank3[addr[22:1]];
1174 
         endcase // case (bank)
1175 
 
1176 
         // set the byte in the short
1177 
         if (!addr[0])
1178 
           short[15:8] = data;
1179 
         else
1180 
           short[7:0] = data;
1181 
 
1182 
         // Write short back to memory
1183 
         case(bank)
1184 
           2'b00:
1185 
             Bank0[addr[22:1]] = short;
1186 
           2'b01:
1187 
             Bank1[addr[22:1]] = short;
1188 
           2'b10:
1189 
             Bank2[addr[22:1]] = short;
1190 
           2'b11:
1191 
             Bank3[addr[22:1]] = short;
1192 
         endcase // case (bank)
1193 403 julius 
 
1194 
      end
1195 495 julius 
   endtask // set_byte
1196 
 
1197 
   task get_short;
1198 
      input [31:0] addr;
1199 
      output [15:0] data;
1200 
      reg [1:0]     bank;
1201 
      reg [15:0]   short;
1202 
 
1203 
      begin
1204 
         bank = addr[24:23];
1205 
 
1206 
         case(bank)
1207 
           2'b00:
1208 
             short = Bank0[addr[22:1]];
1209 
           2'b01:
1210 
             short = Bank1[addr[22:1]];
1211 
           2'b10:
1212 
             short = Bank2[addr[22:1]];
1213 
           2'b11:
1214 
             short = Bank3[addr[22:1]];
1215 
         endcase // case (bank)
1216 
 
1217 
         data = short;
1218 
      end
1219 
   endtask // get_short
1220 403 julius 
 
1221 495 julius 
   task set_short;
1222 
      input [31:0] addr;
1223 
      input [15:0] data;
1224 
      reg [1:0]     bank;
1225 
      begin
1226 
         bank = addr[24:23];
1227 
 
1228 
         // Write short back to memory
1229 
         case(bank)
1230 
           2'b00:
1231 
             Bank0[addr[22:1]] = data;
1232 
           2'b01:
1233 
             Bank1[addr[22:1]] = data;
1234 
           2'b10:
1235 
             Bank2[addr[22:1]] = data;
1236 
           2'b11:
1237 
             Bank3[addr[22:1]] = data;
1238 
         endcase // case (bank)
1239 
      end
1240 
   endtask // set_short
1241 
 
1242 6 julius 
endmodule

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