SI2457-D-FS Silicon Laboratories Inc, SI2457-D-FS Datasheet - Page 88

• Manufacturer Part Number: SI2457-D-FS
• Description: IC ISOMODEM SYSTEM-SIDE 16SOIC
• Manufacturer: Silicon Laboratories Inc

Specifications of SI2457-D-FS

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

AN93
5.6. S Registers
S registers are typically used to set modem configuration parameters during initialization and are not usually
changed during normal modem operation. S-register values other than defaults must be written via the ATSn=x
command after every reset event. S registers are specified as a decimal value (S1 for example), and the contents
of the register are also decimal numbers. Table 45 lists the S registers available on the ISOmodem, their functions,
default values, ranges of values, and units.
Many S registers are industry standards, such as S0 (number of rings for auto answer), S1 (ring count), and S2
(escape character) among others. However, there are usually variations in the function (and availability) of S
registers from one chipset to another or from one chipset manufacturer to another. These variations are due to a
combination of feature availability and choices made during the chip design. It is prudent to verify the compatibility
of S-register functions, defaults, ranges, and values when adapting the ISOmodem to an existing design that uses
another chipset. This simple step can save time and help speed product development. If a particular S register is
not available on the ISOmodem, the register may not be necessary, or the function of the S register may be
available with the use of U registers (discussed later) or through an AT command.
88
S Register
(Decimal)
0
1
2
3
4
5
6
7
8
9
Automatic answer—This value represents the number
of rings the ISOmodem must detect before answering
a call. 0 disables auto answer.
Ring counter—Counts rings received on current call.
ESC code character
Carriage return character
Linefeed character
Backspace character
Dial tone wait timer—This timer sets the number of
seconds the ISOmodem waits before blind dialing and
is only active if blind dialing is enabled (X0, X1, X3).
Carrier wait timer—This timer starts when dialing is
completed. It sets the number of seconds the modem
waits without carrier before hanging up and the num-
ber of seconds the modem waits for ringback when
originating a call before hanging up. The register also
sets the number of seconds the answer tone continues
while using the AT*Y2A command.
Dial pause timer for “,” and “<” dial command modifiers
Carrier presence timer—Time the remote modem car-
rier must be detected before activating or reactivating
DCD (carrier loss debounce time).
Table 45. S-Register Descriptions
Function
Definition
Rev. 1.3
(Decimal)
13 (CR)
Default
08 (BS)
10 (LF)
43 (+)
02
80
02
06
0
0
Range
0–255
0–255
0–255
0–255
0–255
0–255
0–255
0–255
0–255
1–255
0.1 second
seconds
seconds
seconds
(ASCII)
(ASCII)
(ASCII)
(ASCII)
Units
rings
rings