LISA-U series - System Integration Manual
UBX-13001118 - R17
Advance information
System description
Page 61 of 190
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
[3] 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
[3], 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
[3] 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
[3], &D AT command).
Only on all LISA-U2 series modules except for ”x0” and “x1” product versions, 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
[3], AT+UPSV command.
