cx20493-35/app Conexant Systems, Inc., cx20493-35/app Datasheet - Page 50

• Manufacturer Part Number: cx20493-35/app
• Description: With Cx20493 Smartdaa?
• Manufacturer: Conexant Systems, Inc.

Table 3-4. CX81801 Modem Pin Signal Definitions for Serial Interface (PARIF = Low) (Continued)
3-18
TXD# (PA2)
RXD# (PA6)
CTS# (PC1)
DSR# (PC0)
RLSD# (PC2)
TM# (PC6)
RI# (PC5)
DTR# (PD4)
RTS# (PD6)
CX81801-7x/8x SmartV.XX Modem in 128-Pin LQFP with CX20493 in 32-Pin LQFP Data Sheet
Label
27
32
123
122
125
3
1
11
13
Pin
V.24 (EIA/TIA-232-E) DTE Serial Interface
I
O
O
O
O
O
O
I
I
I/O
It/Ot2
It/Ot2
Ith/Ot8
Ith/Ot8
Ith/Ot8
Ith/Ot8
Ith/Ot8
It
Ithpu
I/O Type
Conexant
Transmitted Data (EIA BA/ITU-T CT103). The DTE uses the
TXD# line to send data to the modem for transmission over the
telephone line or to transmit commands to the modem.
Received Data (EIA BB/ITU-T CT104). The modem uses the
RXD# line to send data received from the telephone line to the
DTE and to send modem responses to the DTE. During command
mode, RXD# data represents the modem responses to the DTE.
Clear To Send (EIA CB/ITU-T CT106). CTS# output ON (low)
indicates that the modem is ready to accept data from the DTE. In
asynchronous operation, in error correction or normal mode, CTS#
is always ON (low) unless RTS/CTS flow control is selected by the
&Kn command.
In synchronous operation, the modem also holds CTS# ON during
asynchronous command state. The modem turns CTS# OFF
immediately upon going off-hook and holds CTS# OFF until both
DSR# and RLSD# are ON and the modem is ready to transmit and
receive synchronous data. The modem can also be commanded
by the &Rn command to turn CTS# ON in response to an RTS#
OFF-to-ON transition.
Data Set Ready (EIA CC/ITU-T CT107). DSR# indicates modem
status to the DTE. DSR# OFF (high) indicates that the DTE is to
disregard all signals appearing on the interchange circuits except
Ring Indicator (RI#). DSR# output is controlled by the AT&Sn
command.
Received Line Signal Detector (EIA CF/ITU-T CT109). When
AT&C0 command is not in effect, RLSD# output is ON when a
carrier is detected on the telephone line or OFF when carrier is not
detected.
Test Mode (EIA TM/ITU-T CT142). The TM# output indicates the
modem is in test mode (low) or in any other mode (high).
Ring Indicator (EIA CE/ITU-T CT125). RI# output ON (low)
indicates the presence of an ON segment of a ring signal on the
telephone line.
Data Terminal Ready (EIA CD/ITU-T CT108). The DTR# input is
turned ON (low) by the DTE when the DTE is ready to transmit or
receive data. DTR# ON prepares the modem to be connected to
the telephone line, and maintains the connection established by
the DTE (manual answering) or internally (automatic answering).
DTR# OFF places the modem in the disconnect state under
control of the &Dn and &Qn commands.
Request To Send (EIA CA/ITU-T CT105). RTS# input ON (low)
indicates that the DTE is ready to send data to the modem. In the
command state, the modem ignores RTS#.
In asynchronous operation, the modem ignores RTS# unless
RTS/CTS flow control is selected by the &Kn command. In
synchronous on-line operation, the modem can be commanded by
the &Rn command to ignore RTS# or to respond to RTS# by
turning on CTS# after the delay specified by Register S26.
Signal Name/Description
102247B