Specifications

AN93
60 Rev. 0.8
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 (S01 for
example), and the contents of the register are always a
decimal number. Table 32 lists the S-Registers available
on the Si2493/57/34/15/04, their function, default value,
range of values, and units.
Many S-Registers are becoming 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.
Verify S-Register functions, defaults, ranges, and values
when adapting the Si2493/57/34/15/04 to an existing
design. This simple step can save time and help speed
product development. If a particular S-Register is not
available on the Si2493/57/34/15/04, 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.
Table 32. S-Register Descriptions
Definition
S-Register
(Decimal)
Function Default
(Decimal)
Range Units
0 Automatic answer—This value represents the number
of rings the Si2493/57/34/15/04 must detect before
answering a call. 0 disables auto answer.
0 0–255 rings
1 Ring counter—Counts rings received on current call. 0 0–255 rings
2 ESC code character 43 (+) 0–255 ASCII
3 Carriage return character 13 (CR) 0–255 ASCII
4 Linefeed character 10 (LF) 0–255 ASCII
5 Backspace character 08 (BS) 0–255 ASCII
6 Dial tone wait timer—This timer sets the number of
seconds the Si2493/57/34/15/04 waits before blind
dialing and is only active if blind dialing is enabled (X0,
X1, X3).
02 0–255 seconds
7 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.
80 0–255 seconds
8 Dial pause timer for “,” and “<” dial command modifiers 02 0–255 seconds
9 Carrier presence timer—Time the remote modem car-
rier must be detected before activating or reactivating
DCD
(carrier loss debounce time).
06 1–255 0.1 second