1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
|
/////////////////////////////////////////////////////////////////////
//// ////
//// WISHBONE revB.2 compliant I2C Master controller Top-level ////
//// ////
//// ////
//// Author: Richard Herveille ////
//// richard@asics.ws ////
//// www.asics.ws ////
//// ////
//// Downloaded from: http://www.opencores.org/projects/i2c/ ////
//// ////
/////////////////////////////////////////////////////////////////////
//// ////
//// Copyright (C) 2001 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_master_top.v,v 1.11 2005/02/27 09:26:24 rherveille Exp $
//
// $Date: 2005/02/27 09:26:24 $
// $Revision: 1.11 $
// $Author: rherveille $
// $Locker: $
// $State: Exp $
//
// Change History:
// $Log: i2c_master_top.v,v $
// Revision 1.11 2005/02/27 09:26:24 rherveille
// Fixed register overwrite issue.
// Removed full_case pragma, replaced it by a default statement.
//
// Revision 1.10 2003/09/01 10:34:38 rherveille
// Fix a blocking vs. non-blocking error in the wb_dat output mux.
//
// Revision 1.9 2003/01/09 16:44:45 rherveille
// Fixed a bug in the Command Register declaration.
//
// Revision 1.8 2002/12/26 16:05:12 rherveille
// Small code simplifications
//
// Revision 1.7 2002/12/26 15:02:32 rherveille
// Core is now a Multimaster I2C controller
//
// Revision 1.6 2002/11/30 22:24:40 rherveille
// Cleaned up code
//
// Revision 1.5 2001/11/10 10:52:55 rherveille
// Changed PRER reset value from 0x0000 to 0xffff, conform specs.
//
// synopsys translate_off
//`include "timescale.v"
// synopsys translate_on
`include "i2c_master_defines.v"
module i2c_master_top(
wb_clk_i, wb_rst_i, arst_i, wb_adr_i, wb_dat_i, wb_dat_o,
wb_we_i, wb_stb_i, wb_cyc_i, wb_ack_o, wb_inta_o,
scl_pad_i, scl_pad_o, scl_padoen_o, sda_pad_i, sda_pad_o, sda_padoen_o );
// parameters
parameter ARST_LVL = 1'b0; // asynchronous reset level
//
// inputs & outputs
//
// wishbone signals
input wb_clk_i; // master clock input
input wb_rst_i; // synchronous active high reset
input arst_i; // asynchronous reset
input [2:0] wb_adr_i; // lower address bits
input [7:0] wb_dat_i; // databus input
output [7:0] wb_dat_o; // databus output
input wb_we_i; // write enable input
input wb_stb_i; // stobe/core select signal
input wb_cyc_i; // valid bus cycle input
output wb_ack_o; // bus cycle acknowledge output
output wb_inta_o; // interrupt request signal output
reg [7:0] wb_dat_o;
reg wb_ack_o;
reg wb_inta_o;
// I2C signals
// i2c clock line
input scl_pad_i; // SCL-line input
output scl_pad_o; // SCL-line output (always 1'b0)
output scl_padoen_o; // SCL-line output enable (active low)
// i2c data line
input sda_pad_i; // SDA-line input
output sda_pad_o; // SDA-line output (always 1'b0)
output sda_padoen_o; // SDA-line output enable (active low)
//
// variable declarations
//
// registers
reg [15:0] prer; // clock prescale register
reg [ 7:0] ctr; // control register
reg [ 7:0] txr; // transmit register
wire [ 7:0] rxr; // receive register
reg [ 7:0] cr; // command register
wire [ 7:0] sr; // status register
// done signal: command completed, clear command register
wire done;
// core enable signal
wire core_en;
wire ien;
// status register signals
wire irxack;
reg rxack; // received aknowledge from slave
reg tip; // transfer in progress
reg irq_flag; // interrupt pending flag
wire i2c_busy; // bus busy (start signal detected)
wire i2c_al; // i2c bus arbitration lost
reg al; // status register arbitration lost bit
//
// module body
//
// generate internal reset
wire rst_i = arst_i ^ ARST_LVL;
// generate wishbone signals
wire wb_wacc = wb_cyc_i & wb_stb_i & wb_we_i;
// generate acknowledge output signal
always @(posedge wb_clk_i)
wb_ack_o <= #1 wb_cyc_i & wb_stb_i & ~wb_ack_o; // because timing is always honored
// assign DAT_O
always @(posedge wb_clk_i)
begin
case (wb_adr_i) // synopsis parallel_case
3'b000: wb_dat_o <= #1 prer[ 7:0];
3'b001: wb_dat_o <= #1 prer[15:8];
3'b010: wb_dat_o <= #1 ctr;
3'b011: wb_dat_o <= #1 rxr; // write is transmit register (txr)
3'b100: wb_dat_o <= #1 sr; // write is command register (cr)
3'b101: wb_dat_o <= #1 txr;
3'b110: wb_dat_o <= #1 cr;
3'b111: wb_dat_o <= #1 0; // reserved
endcase
end
// generate registers
always @(posedge wb_clk_i or negedge rst_i)
if (!rst_i)
begin
prer <= #1 16'hffff;
ctr <= #1 8'h0;
txr <= #1 8'h0;
end
else if (wb_rst_i)
begin
prer <= #1 16'hffff;
ctr <= #1 8'h0;
txr <= #1 8'h0;
end
else
if (wb_wacc)
case (wb_adr_i) // synopsis parallel_case
3'b000 : prer [ 7:0] <= #1 wb_dat_i;
3'b001 : prer [15:8] <= #1 wb_dat_i;
3'b010 : ctr <= #1 wb_dat_i;
3'b011 : txr <= #1 wb_dat_i;
default: ;
endcase
// generate command register (special case)
always @(posedge wb_clk_i or negedge rst_i)
if (~rst_i)
cr <= #1 8'h0;
else if (wb_rst_i)
cr <= #1 8'h0;
else if (wb_wacc)
begin
if (core_en & (wb_adr_i == 3'b100) )
cr <= #1 wb_dat_i;
end
else
begin
if (done | i2c_al)
cr[7:4] <= #1 4'h0; // clear command bits when done
// or when aribitration lost
cr[2:1] <= #1 2'b0; // reserved bits
cr[0] <= #1 2'b0; // clear IRQ_ACK bit
end
// decode command register
wire sta = cr[7];
wire sto = cr[6];
wire rd = cr[5];
wire wr = cr[4];
wire ack = cr[3];
wire iack = cr[0];
// decode control register
assign core_en = ctr[7];
assign ien = ctr[6];
// hookup byte controller block
i2c_master_byte_ctrl byte_controller (
.clk ( wb_clk_i ),
.rst ( wb_rst_i ),
.nReset ( rst_i ),
.ena ( core_en ),
.clk_cnt ( prer ),
.start ( sta ),
.stop ( sto ),
.read ( rd ),
.write ( wr ),
.ack_in ( ack ),
.din ( txr ),
.cmd_ack ( done ),
.ack_out ( irxack ),
.dout ( rxr ),
.i2c_busy ( i2c_busy ),
.i2c_al ( i2c_al ),
.scl_i ( scl_pad_i ),
.scl_o ( scl_pad_o ),
.scl_oen ( scl_padoen_o ),
.sda_i ( sda_pad_i ),
.sda_o ( sda_pad_o ),
.sda_oen ( sda_padoen_o )
);
// status register block + interrupt request signal
always @(posedge wb_clk_i or negedge rst_i)
if (!rst_i)
begin
al <= #1 1'b0;
rxack <= #1 1'b0;
tip <= #1 1'b0;
irq_flag <= #1 1'b0;
end
else if (wb_rst_i)
begin
al <= #1 1'b0;
rxack <= #1 1'b0;
tip <= #1 1'b0;
irq_flag <= #1 1'b0;
end
else
begin
al <= #1 i2c_al | (al & ~sta);
rxack <= #1 irxack;
tip <= #1 (rd | wr);
irq_flag <= #1 (done | i2c_al | irq_flag) & ~iack; // interrupt request flag is always generated
end
// generate interrupt request signals
always @(posedge wb_clk_i or negedge rst_i)
if (!rst_i)
wb_inta_o <= #1 1'b0;
else if (wb_rst_i)
wb_inta_o <= #1 1'b0;
else
wb_inta_o <= #1 irq_flag && ien; // interrupt signal is only generated when IEN (interrupt enable bit is set)
// assign status register bits
assign sr[7] = rxack;
assign sr[6] = i2c_busy;
assign sr[5] = al;
assign sr[4:2] = 3'h0; // reserved
assign sr[1] = tip;
assign sr[0] = irq_flag;
endmodule
|
