Si2401
28
Preliminary Rev. 0.9
At this point, users may program their own algorithm to
monitor the detected tones. If the host wishes to dial, it
should do so by blind dialing, setting the dial timeout
S01 (DW) to 0 seconds and issuing an
“ATDT<Phone Number>;<CR>” command. This
immediately causes the ISOmodem
®
chipset to dial and
return to command mode.
Once the host has detected an answer tone using
manual call progress, the host should immediately
execute the “ATDT” command in order to make a
connection. This causes the Si2401 to search for the
modem answer tone and begin the correct connect
sequence.
In manual call progress, the DSP can be programmed
to detect specific tones. The result of the detection is
reported in SE5 (SE8 = 0x2) as explained above. The
output is priority-encoded such that if multiple tones are
detected, the one with the highest priority whose
detection is also enabled is reported (see SE5 [SE8=02]
Read Only.)
In manual call progress, the DSP can be programmed
to generate specific tones (see SE5[2:0] (TONC)
(SE8 = 02) Write Only). For example, setting
SE5[2:0] (TONC) = 110
b
generates the user-defined
tone (as indicated by UFRQ in Table 18) with an
amplitude of TGNL.
Table 17 shows the mappings of Si2401 DTMF values,
keyboard equivalents, and the related dual tones.
Table 17. DTMF Values
DTMF
Code
Keyboard
Equivalent
Contact
ID
Digit
Tones
Low
High
0
0
0
941
1336
1
1
1
697
1209
2
2
2
697
1336
3
3
3
697
1477
4
4
4
770
1209
5
5
5
770
1336
6
6
6
770
1477
7
7
7
852
1209
8
8
8
852
1336
9
9
9
852
1477
10
D
–
941
1633
11
*
B
941
1209
12
#
C
941
1477
13
A
D
697
1633
14
B
E
770
1633
15
C
F
852
1633
