Silicon Laboratories SI2493/57/34/15/04 - Manual (Page 231)

AN93
Rev. 1.3 231
7 AT:U181,78,0,0,1C OK Set up 1400 Hz detector to
detect 100 ms Handshake tone
burst.
8 ATDnnnnnnn OK Call RECEIVER station.
9 AT+VTD=5;:U48,32 OK Change DTMF on off time to pre-
pare for Data Tones transmis-
sion.
10 Wait for RECEIVER to answer with handshake tones
11
i.e. 0x10, 0x63
1400 Hz tone burst detected
Note: First part of Handshake
Tones detected.
12
i.e. 0x10, 0x65
2300 Hz tone burst detected
Notes: Second part of Hand-
shake Tones detected.
Since there is a 100 ms silence
between the 1400 Hz and
2300 Hz tones, the
message should come nomi-
nally 200msec after the previous
message.
It is the responsibility of the host
DTE driver to measure and vali-
date this time period.
13 AT:U181,334,0,0,12C OK Change 1400 Hz detector to
detect 800 ±300 ms tone burst,
i.e. Kissoff tone.
14 Delay 250 ms before transmitting Data Tones
message. Host DTE should adjust this
delay so that the following +VTS
DTMF transmission will start
between 250 to 300 ms after the
reception of above.
Table 145. Ademco
®
Mode of Operation (Continued)
Step DTE-to-Modem Command Modem-to-DTE
Indication
Remarks