LISA-U2 series - System integration manual
UBX-13001118 - R27
System description
Page 60 of 183
C1-Public
ON state, then answers with a CONNECT to confirm the ATD*99 command. The
DCD
ON is not
related to the context activation but with the data mode.
•
CSD data call
: To establish a data call, the DTE can send the ATD<number> command to the
module which sets an outgoing data call to a remote modem (or another data module). Data can
be transparent (non-reliable) or non-transparent (with the reliable RLP protocol). When the remote
DCE accepts the data call, the module
DCD
line is set to ON and the CONNECT <communication
baudrate> string is returned by the module. At this stage, the DTE can send characters through
the serial line to the data module which sends them through the network to the remote DCE
attached to a remote DTE.
☞
For a voice call,
DCD
is set to ON state on all the serial communication interfaces supporting the
AT command interface (including MUX virtual channels, if active).
☞
DCD
is set to ON during the execution of a command that requires input data from the DTE (all the
commands where a prompt is issued; see AT coCMGS, +CMGW, +USOWR, +USODL,
+UDWNFILE in the u-blox AT commands manual
). The
DCD
line is set to ON state as soon as
the switch to binary/text input mode is completed and the prompt is issued;
DCD
line is set to OFF
as soon as the input mode is interrupted or completed.
☞
DCD
line is kept to ON state even during the online command mode to indicate that the data call
is still established even if suspended, while if the module enters command mode, the
DSR
line is
set to OFF state. For more details, see the
signal behavior description.
☞
For scenarios where the
DCD
line setting is requested for various reasons (e.g. SMS texting during
online command mode), the
DCD
line changes to guarantee the correct behavior for all the
scenarios. For instance, in case of SMS texting in online command mode, if the data call is
released, the
DCD
line will be kept to ON until the SMS command execution is completed (even if
the data call release would request the
DCD
setting to OFF).
RI signal behavior
The
RI
module output line is set by default to the OFF state (high level) at UART initialization. Then,
during an incoming call, the
RI
line is switched from OFF state to ON state with a 4:1 duty cycle and a
5 s period (ON for 1 second, OFF for 4 seconds, see
), until the DTE attached to the module
sends the ATA string and the module accepts the incoming data call. The RING string sent by the
module (DCE) to the serial port at constant time intervals is not correlated with the switch of the
RI
line to the ON state.
Figure 26: RI behavior during an incoming call
The
RI
line can notify an SMS arrival. When the SMS arrives, the
RI
line switches from OFF to ON for
1 s (see
), if the feature is enabled by the appropriate AT command (see the u-blox AT
, AT+CNMI command).
1s
time [s]
15
10
5
0
RI ON
RI OFF
Call incomes
1s
time [s]
15
10
5
0
RI ON
RI OFF
Call incomes
