Si2401
Preliminary Rev. 0.9
23
H1
Off-hook
Go off-hook.
I
Chip Identification
This command causes the modem to echo the chip
revision for the Si2401 device.
A = Revision A
B = Revision B
C = Revision C, etc.
I6
Display the ISOmodem
®
model number.
“2401” = Si2401.
:I
Interrupt Read
This command causes the ISOmodem chipset to report
the contents of the interrupt status register (S09). The
WOR, PPD, NLD, RI, OCD, and REV bits are also
cleared, and the INT is deactivated on this read.
M
Speaker On/Off Options
These options are used to control AOUT for use with a
call progress monitor speaker.
M0
Speaker always off.
M1
Speaker on until carrier established. The modem sets
SF4[3:2] (ARL) = 11 and SF4[1:0] (ATL) = 11 after a
connection is established.
M2
Speaker always on.
M3
Speaker on after last digit dialed, off at carrier detect.
O
Return to Online Mode
This command returns the modem to the online mode. It
is frequently used after an escape sequence to resume
communication with the remote modem.
RO
Turn-Around
This command initiates a V.23 “direct turnaround”
sequence and returns online.
S
S Register Control
SR=N
Write an S register. This command writes the value “N”
to the S-register specified by “R”. “R” is a hexidecimal
number, and “N” must also be a hexadecimal number
from 00–FF. This command does not wait for a carriage
return <CR> before taking effect.
Note:
Two digits must always be entered for both “R” and “N”.
SR?
Read an S register. This command causes the Si2401
to echo the value of the S-register specified by R in hex
format. R must be a hexidecimal number.
Note:
Two digits must always be entered for R.
w##
Write S Register in Binary
This command writes a register in binary format. The
first byte following the “w” is the address in binary
format and the second byte is the data in binary format.
This is a more rapid method to write registers than the
“SR=N” command and is recommended for use by a
host microcontroller.
r#
Read S Register in Binary
This command reads a register in binary format. The
byte following the “r” is the address in binary format.
The modem echoes the contents of this register in
binary format. This is a more rapid method to read
registers than the “SR?” command and is
recommended for use by a host microcontroller.
Notes:
1. w## and r# are not required to be on separate lines (i.e.,
no <CR> between them). Also, the result of an r# is
returned immediately without waiting for a <CR> at the end
of the AT command line.
2. Once a <CR> is encountered, “AT” is again required to
begin the next “AT” command.
m#
Monitor S Register in Binary
This command monitors a register in binary format. The
byte following the “m” is the address in binary format.
The Si2401 constantly transmits the contents of the
register at the set baud rate until a new byte is
transmitted to the device. The new byte is ignored and
viewed as a stop command. The modem result codes
should be disabled (as described above in r#) before
using this command.
q#
Read S Register in Binary
This command is exactly the same as the r# command;
however, the response from the Si2401 is formatted as
0x55 followed by the contents of the register in binary.
This guarantees that the register contents are always
preceded by 0x55 and allows the result codes to remain
enabled.
V
Result Code Options
V0
Result codes reported according to Table 14.
V1
Result codes reported with an additional carriage return
and line feeds (default).
Z
Software Reset
The “Z” command initiates a software reset causing all
registers, with the exception of E0, which controls the
DTE settings, to default to their powerup value.
