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TOBY-R2 series - System integration manual
UBX-16010572 - R10
System description
Page 39 of 151
DSR signal behavior
If AT&S1 is set, as it is by default, the DSR module output line is set by default to the OFF state (high
level) at UART initialization. The DSR line is then set to the OFF state when the module is in command
mode
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or in online command mode
and is set to the ON state when the module is in data mode
If AT&S0 is set, the DSR module output line is set by default to the ON state (low level) at UART
initialization and is then always held in the ON state.
DTR signal behavior
The DTR module input line is set by default to the OFF state (high level) at UART initialization. The
module then holds the DTR line in the OFF state if the line is not activated by the DTE: an active pull-
up is enabled inside the module on the DTR input.
Module behavior according to DTR status can be changed by AT command configuration (for more
details see the u-blox AT commands manual
, &D AT command description).
If AT+UPSV=3 is set, the DTR line is monitored by the module to manage the power saving
configuration (for more details, see section
, AT+UPSV):
When an OFF-to-ON transition occurs on the DTR input, the UART is enabled and the module is
forced to active-mode. After ~20 ms, the switch is completed and data can be received without
loss. The module cannot enter low power idle-mode and the UART is enabled as long as the DTR is
in the ON state
If the DTR input line is set to the OFF state by the DTE, the UART is disabled (held in low power
mode) and the module automatically enters low power idle-mode whenever possible
DCD signal behavior
If AT&C1 is set, as it is by default, the DCD module output line is set by default to the OFF state (high
level) at UART initialization. The module then sets the DCD line according to the carrier detect status:
ON if the carrier is detected, OFF otherwise.
For voice calls, DCD is set to the ON state when the call is established.
For data calls, there are the following scenarios regarding the DCD signal behavior:
Packet Switched Data call: Before activating the PPP protocol (data mode) a dial-up application
must provide the ATD*99***<context_number># to the module: with this command the module
switches from command mode to data mode and can accept PPP packets. The module sets the
DCD line to the 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
Circuit Switched 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
☞
The DCD is set to ON during the execution of the +CMGS, +CMGW, +USOWR, +USODL AT
commands requiring input data from the DTE: the DCD line is set to the 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 (for more details see the u-blox AT commands
manual
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For the definition of the interface data mode, command mode and online command mode see the u-blox AT commands
manual