Installation Instructions

LISA-U2 series - System Integration Manual
UBX-13001118 - R19 Early Production Information System description
Page 58 of 175
RTS signal behavior
The hardware flow control input (RTS line) is set by default to the OFF state (high level) at UART initialization.
The RTS line is then held by the module 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 (for more details see the u-blox AT Commands Manual [2] AT&K, AT\Q,
AT+IFC command description) the RTS line is monitored by the module to detect permission from the DTE to
send data to the DTE itself. If the RTS line is set to OFF state, any on-going data transmission from the module is
immediately interrupted or any subsequent transmission forbidden until the RTS line changes to ON state.
The DTE must be able to still accept a certain number of characters after the RTS line has been set to OFF
state: the module guarantees the transmission interruption within 2 characters from RTS state change.
If AT+UPSV=2 is set and HW flow control is disabled, the RTS line is monitored by the module 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 is forced
to active-mode: after 20 ms from the transition the switch is completed and data can be received without
loss. The module cannot enter idle-mode and the UART is keep enabled as long as the RTS input line is held
in the ON state
 If RTS is set to OFF state by the DTE, the UART is immediately disabled (held in low power mode) and the
module automatically enters idle-mode whenever possible
For more details on the power saving configuration controlled by the RTS input line see section 1.9.2.3 and
u-blox AT Commands Manual [2], AT+UPSV command.
DSR signal behavior
If AT&S0 is set, the DSR module output line is set by default to ON state (low level) at UART initialization and is
then always held in the ON state.
If AT&S1 is set, the DSR module output line is set by default to 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 [2] for the
definition of the interface data mode, command mode and online command mode).
The above behavior is valid for both Packet-Switched and Circuit-Switched Data transfer.
DTR signal behavior
The DTR module input line is set by default to OFF state (high level) at UART initialization. The DTR line is then
held by the module 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 depends on the AT command
configuration (see u-blox AT Commands Manual [2], &D AT command).
Except for “01” product version, 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 is forced
to active-mode: after 20 ms from the transition the switch is completed and data can be received without
loss. The module cannot enter idle-mode and the UART is keep enabled as long as the DTR input line is held
in the ON state
 If DTR is set to OFF state by the DTE, the UART is immediately disabled (held in low power mode) and the
module automatically enters idle-mode whenever possible
For more details on the power saving configuration controlled by the DTR input line see section 1.9.2.3 and
u-blox AT Commands Manual [2], AT+UPSV command.