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| 型号： | SI3225PPT0-EVB |
| 厂商： | Silicon Laboratories Inc |
| 文件页数： | 79/112页 |
| 文件大小： | 0K |
| 描述： | BOARD EVAL W/SI3200 INTERFACE |
| 标准包装： | 1 |
| 系列： | ProSLIC® |
| 类型： | ADC + DAC，编码解码器，前端 |
| 适用于相关产品： | Si3225 |
| 所含物品： | 评估板和光盘 |
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Si3220/25 Si3200/02
Rev. 1.3
69
Not
Recommended
fo
r N
ew
D
esi
gn
s
Figure 38. Pulse Metering Generation Block Diagram
3.23. DTMF Detection
On-chip DTMF detection, also known as touch tone, is
available in the Si3220 and Si3225.
It is an in-band signaling system that replaces the pulse-
dial signaling standard. In DTMF, two tones generate a
DTMF digit. One tone is chosen from the four possible
row tones, and one tone is chosen from the four
possible column tones. The sum of these tones
constitutes one of 16 possible DTMF digits. The row
and column tones and corresponding digits are shown
in Table 39.
DTMF detection is performed using a modified Goertzel
algorithm to compute the DFT for each of the eight
DTMF frequencies and their second harmonics. At the
end of the DFT computation, the squared magnitudes of
the DFT results for the 8 DTMF fundamental tones are
computed. The row results are sorted to determine the
strongest row frequency, and the column frequencies
are sorted as well. Upon completion of this process,
checks are made to determine if the strongest row and
column tones constitute a DTMF digit.
The detection process occurs twice within the 45 ms
minimum tone time. A digit must be detected on two
consecutive tests after a pause to be recognized as a
new digit. If all tests pass, an interrupt is generated, and
the DTMF digit value is loaded into the DTMF register
according to Table 39. If tones occur at the maximum
rate of 100 ms per digit, the interrupt must be serviced
within 85 ms so that the current digit is not overwritten
by a new one. There is no buffering of the digit
information.
Decimation
Filter
ADC
DAC
Pulse
Metering
DAC
Pulse
Metering
Oscillator
Volume
PMRAMP
Peak Detector
PMAMPTH
Z
A
I
BUF
8 kHz
7FFF
or 0
Clip
Logic
–
+
12/16 kHz
Bandpass
+
+
+
x
+
±
Table 39. DTMF Row/Column Tones
697 Hz
1
2
3
A
770 Hz
4
5
6
B
852 Hz
7
8
9
C
941 Hz
*
0
#
D
1209 Hz
1336 Hz
1477 Hz
1633 Hz
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相关代理商/技术参数 |
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|---|---|
| SI3225PPT-EVB | 制造商:SILABS 制造商全称:SILABS 功能描述:EVALUATION BOARD FOR THE Si3225 DUAL PROSLIC |
| SI3225PPTX-EVB | 功能描述:音频 IC 开发工具 Si3225 Eval Board RoHS:否 制造商:Texas Instruments 产品:Evaluation Kits 类型:Audio Amplifiers 工具用于评估:TAS5614L 工作电源电压:12 V to 38 V |
| SI3225-X-FQ | 制造商:SILABS 制造商全称:SILABS 功能描述:DUAL PROSLIC㈢ PROGRAMMABLE CMOS SLIC/CODEC |
| SI3225-X-GQ | 制造商:SILABS 制造商全称:SILABS 功能描述:DUAL PROSLIC㈢ PROGRAMMABLE CMOS SLIC/CODEC |
| SI3226 | 制造商:SILABS 制造商全称:SILABS 功能描述:Dual ProSLIC㈢ with DC-DC Controller |
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