SI2493-C-FT Silicon Laboratories Inc, SI2493-C-FT Datasheet - Page 111

• Manufacturer Part Number: SI2493-C-FT
• Description: 56 KBPS, V.92 ISOMODEM SYSTEM-SIDE - LEAD-FREE TSSOP 0 TO 7
• Manufacturer: Silicon Laboratories Inc

Specifications of SI2493-C-FT

• Mfg Application Notes: SI2493/57/34/15/04, Appl Note AN93
• Data Format: V.21, V.22, V.23, V.29, V.32, V.34, V.90, V.92, Bell 103, Bell 212A
• Baud Rates: 56k
• Interface: Parallel
• Voltage - Supply: 3 V ~ 3.6 V
• Mounting Type: Surface Mount
• Package / Case: 24-TSSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

3.5.3. SMS Support
Short Message Service (SMS) is a service that allows
text messages to be sent and received from one
telephone to another via an SMS service center. The
Si2493/57/34/15/04 provides an interface that offers a
great deal of flexibility in handling multiple SMS
standards. This flexibility is possible because most of
the differences between standards is handled by the
host in the data itself. The Si24xx performs the
necessary modulation of the data and provides two
options for message packet structure (Protocol 1 and
Protocol 2, as defined in ETSI ES 201 912). The rest of
the data link layer and transfer layer are defined by the
host system.
The Si24xx uses a V.23 half-duplex modulation to
transmit and receive the data over the PSTN.
Two packet structures are provided: Protocol 1 and
Protocol 2. Protocol 2 differs from Protocol 1 in that a
packet is preceded by 300 bits of channel seizure. ETSI
ES 201 912 describes the other differences between
Protocols 1 and 2, but the host processor handles these
when structuring the data within the packet.
There are four commands that control the behavior of
the SMS feature.
300 bits of channel seizure
(alternating 1’s and 0’s)
80 bits of mark (constant 1s)
Table 77. Protocol 1
Table 78. Protocol 2
80 bits of mark
(constant 1s)
Message
Message
Rev. 0.9
To enable the SMS features on the Si24xx, the host
must send “AT+FCLASS = 256” to the modem prior to
handling an SMS call. The host can then dial or answer
an SMS call using the “ATDTxxxx;” (where xxxx is the
number
respectively. Note the semi-colon at the end of the
command, which places the modem immediately into
command mode after dialing and responds with “OK”.
The host can then prepare the modem for transmitting
or receiving SMS data.
To receive Protocol 1 or Protocol 2 data, the host must
send “AT+FRM = 200”. This causes the modem to
return to data mode silently, listening for data from the
remote SMS server. If the modem detects a valid
Protocol 1 or Protocol 2 packet, it responds with a
“CONNECT” message followed by the SMS message
(without channel seizure and mark). When the carrier
stops, the modem returns to command mode and
responds with “OK”.
AT+FCLASS = 256 Prepares the modem for han-
ATDT;
AT+FRM = 200
AT+FTM = 201
AT+FTM = 202
Command
to
Table 79. SMS Commands
be
dialed)
dling SMS calls.
Goes off-hook and returns to
command mode. If a phone
number is provided, it is dialed
prior to returning to command
mode.
Returns to data mode prepared
to receive an SMS message.
Returns to data mode prepared
to transmit an SMS protocol 1
message.
Returns to data mode prepared
to transmit an SMS protocol 2
message.
SMS Feature Behavior
or
“ATDT;”
AN93
commands,
111