User's Manual

SARA-G3 and SARA-U2 series - System Integration Manual
UBX-13000995 - R08 Objective Specification System description
Page 44 of 188
RTS signal behavior
The hardware flow control input (RTS line) is set by default to the OFF state (high level) at UART initialization.
The module then holds the RTS 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 RTS input.
If the HW flow control is enabled, as it is by default, the module monitors the RTS line to detect permission from
the DTE to send data to the DTE itself. If the RTS line is set to the OFF state, any on-going data transmission
from the module is interrupted until the subsequent RTS line change to the ON state.
The DTE must still be able to accept a certain number of characters after the RTS line is set to the OFF
state: the module guarantees the transmission interruption within two characters from RTS state change.
Module behavior according to RTS hardware flow control status can be configured by AT commands (for more
details, see u-blox AT Commands Manual [3], AT&K, AT\Q, AT+IFC command descriptions).
If AT+UPSV=2 is set and HW flow control is disabled, the module monitors the RTS line to manage the power
saving configuration:
 When an OFF-to-ON transition occurs on the RTS input line, the UART is enabled and the module wakes up
to active-mode: after ~20 ms from the OFF-to-ON transition the UART / module wake up is completed and
data can be received without loss. The module cannot enter the low power idle-mode and the UART is kept
enabled as long as the RTS input line is held in the ON state
 If the RTS 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
For more details, see section 1.9.1.4 and u-blox AT Commands Manual [3], AT+UPSV command.
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 or in online
command mode and is set to the ON state when the module is in data mode (see the u-blox AT Commands
Manual [3] for the definition of the interface data mode, command mode and online command 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 (for more details, see u-blox AT
Commands Manual [3], AT&D command description).
If AT+UPSV=3 is set, the DTR line is monitored by the module to manage the power saving configuration:
 When an OFF-to-ON transition occurs on the DTR input line, the UART is enabled and the module wakes up
to active-mode: after ~20 ms from the OFF-to-ON transition the UART / module wake up is completed and
data can be received without loss. The module cannot enter the low power idle-mode and the UART is kept
enabled as long as the DTR input line is held 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
For more details, see section 1.9.1.4 and u-blox AT Commands Manual [3], AT+UPSV command.
AT+UPSV=3 power saving configuration control by the DTR input is not supported by SARA-G3 modules.