T9000
Preliminary Data Sheet
November 2000
ISDN Network Termination Node (NTN) Device
12 PWM Module (continued)
12.3 PWSM ROM
As mentioned previously, the ROM shown in Figure 22 is used to store the amplitude values of one complete cycle
of a sine wave. The ROM address generated by the accumulator determines the current ROM output value. The
sine amplitudes in the ROM represent a sine wave with a 2.5%—97.5% scale and a dc offset of 128 (out of 256).
The values can be expressed by the following formula:
W(A) = ROUND (128 x [1 + 0.95 x SIN {2 x π x A/256}])
Table 102 illustrates the resulting value W(A) at each ROM address A.
Table 102. ROM Code
Values in decimal (A = address; W = width).
A
0
W
A
W
A
W
A
W
A
W
A
W
42
40
38
36
34
32
30
29
27
25
24
22
21
19
18
17
16
15
14
13
12
11
10
9
A
W
6
A
W
42
44
46
49
51
53
56
58
60
63
65
68
71
73
76
79
81
84
87
90
93
96
98
128
131
134
137
140
143
146
149
152
155
158
160
163
166
169
172
175
177
180
183
185
188
191
193
196
198
200
203
205
207
210
212
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
214
216
218
220
222
224
226
227
229
232
231
234
235
237
238
239
240
241
242
243
244
245
246
247
247
248
248
248
249
249
249
250
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
250
250
249
249
96
97
98
99
214 128 128 160
212 129 125 161
210 130 122 162
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
1
6
2
7
3
207 131
119
116
113
110
163
164
165
166
7
4
249 100 205 132
249 101 203 133
248 102 200 134
7
5
7
6
8
7
248 103 198 135 107 167
247 104 196 136 104 168
247 105 193 137 101 169
8
8
9
9
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
246 106 191 138
245 107 188 139
244 108 185 140
243 109 183 141
98
96
93
90
87
84
81
79
76
73
71
68
65
63
60
58
56
53
51
49
46
44
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
10
11
12
13
14
15
16
17
18
19
21
22
24
25
27
29
30
32
34
36
38
40
242
241
240
239
238
237
235
234
232
231
110
111
112
113
114
115
116
117
118
119
180 142
177 143
175 144
172 145
169 146
166 147
163 148
160 149
158 150
155 151
247 101
248 104
249 107
229 120 152 152
227 121 149 153
226 122 146 154
224 123 143 155
222 124 140 156
220 125 137 157
218 126 134 158
216 127 131 159
9
8
8
250
251
252
253
110
113
116
119
7
7
7
7
254 122
255 125
6
96
Lucent Technologies Inc.
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