
AN93
Rev. 1.4
249
9.2.2. Procedure
To enable the SMS features on the Si24xx, the host sends “AT+FCLASS=256” to the modem prior to an SMS call.
To enable the hardware escape pin functions, the host would set HES with the command “AT:U70|8000”.
After setting the other U-registers according to the configurations of the Originate and Answer modems, the host
can dial an SMS call using the command “ATDTxxxx;” (where xxxx is the number to be dialed) or answer an SMS
call with “ATDT;”. The semi-colon at the end of the command places the modem into command mode after dialing.
The modem responds to the host with “OK”. The host then puts the modem into transmit or receive SMS data
mode.
Many SMS POS protocols perform handshaking using CAS and CAS ACK. CAS is a two-tone signal (2130 Hz /
2750 Hz); CAS ACK is a DTMF ‘D’. The terminal modem connects to the server, which sends CAS tones until it
times out or the terminal modem replies to the server with CAS ACK. The threshold for the modem’s CAS tone
energy detector is set by CTDT, which has a default value of 500h.
The CAS tone must have a minimum duration
of 30 ms to guarantee detection.
CAS detection is enabled by setting the detector threshold UD4 to a value other than 7FFFh. When the CAS
detector is enabled, FSK CS/MARK detection will run after CAS is detected. The modem will time out if CAS is not
detected. (When implementing SMS POS protocols that don’t use CAS and CAS ACK, the CAS tone detector must
be disabled with the command AT:UD4,7FFF.)
Table 162. UD4 SMS CAS Tone Detector Threshold Level
UD4 (Hex)
CAS level (dBm)
0051
–38
0066
–37
0080
–36
00A2
–35
00CB
–34
0100
–33
0142
–32
0196
–31
01FF
–30
0283
–29
032A
–28
03FB
–27
0503
–26
064F
–25
07F1
–24
0A00
–23
0C97
–22
0FD9
–21
Содержание Si2404
Страница 2: ...AN93 2 Rev 1 4 ...
Страница 27: ...AN93 Rev 1 4 27 Figure 7 Parallel Interface Read Timing Figure 8 Parallel Interface Write Timing ...
Страница 200: ...AN93 200 Rev 1 4 Figure 31 TAM Handset and Speakerphone Voice Paths ...
Страница 201: ...AN93 Rev 1 4 201 Figure 32 Si3000 Codec Gain and Signal Selection Options ...
Страница 290: ...AN93 290 Rev 1 4 Figure 57 256 Band Spectral Display Figure 58 2048 Band Spectral Display ...
Страница 305: ...AN93 Rev 1 4 305 Figure 76 Parallel or SPI Port Interrupt Service Flowchart ...