CMX605 Ver la hoja de datos (PDF) - MX-COM Inc
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CMX605 Datasheet PDF : 26 Pages
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Digital Line to POTS Interface
Page 11 of 26
CMX605 Preliminary Information
4.7 DTMF Tone Decoder
This block is enabled or disabled by bit 5 of the SETUP register. If disabled, bit 0 to bit 5 of the STATUS
Register are set to ‘0’ and no interrupts are generated. When enabled (set to ‘1’), a status change of the
decoder will generate an interrupt and bit 5 of the STATUS Register will be set to ‘1’. The validity of the data is
indicated by bit 4 of the STATUS Register. The decode truth table is shown in Table 9.
STATUS Register Bits 0 - 3
Bit 3 Bit 2 Bit 1 Bit 0
(D3) (D2) (D1) (D0)
0
0
0
0
0
0
0
1
0
0
1
0
0
0
1
1
0
1
0
0
0
1
0
1
0
1
1
0
0
1
1
1
1
0
0
0
1
0
0
1
1
0
1
0
1
0
1
1
1
1
0
0
1
1
0
1
1
1
1
0
1
1
1
1
DTMF Tone Pairs
Lower Frequency Upper Frequency
(Hz)
(Hz)
941
1633
697
1209
697
1336
697
1477
770
1209
770
1336
770
1477
852
1209
852
1336
852
1477
941
1336
941
1209
941
1477
697
1633
770
1633
852
1633
Keypad Legend
D
1
2
3
4
5
6
7
8
9
0
*
#
A
B
C
Table 9: DTMF Decode Truth Table
A status change of the decoder and the generation of an interrupt will occur both when a tone is first decoded
and also when a tone, which was previously present, is no longer decoded. In the latter case, Bit 4 of the
STATUS Register will be set to “0” to indicate that no tone was detected.
¤2001 MX-COM, Inc.
www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054
Doc. # 20480195.005
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.
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