Integration Manual

LISA-U2 series - System Integration Manual
UBX-13001118 - R25 System description Page 66 of 182
Figure 29 shows the case where the module UART is disabled and only a wake-up is forced. In this
scenario the only character sent by the DTE is the wake-up character; as a consequence, the DCE
module UART is disabled when the timeout from last data received expires (2000 frames without data
reception, as the default case).
OFF
ON
DCE UART is enabled for 2000 GSM frames (~9.2 s)
time
Wake up time: ~20 ms
time
TXD input
Wake up character
Not recognized by DCE
UART
OFF
ON
Figure 29: Wake-up via data reception without further communication
DCE UART is enabled for 2000 GSM frames (~9.2s)
after the last data received
time
Wake up time: ~20 ms
time
Wake up character
Not recognized by DCE
Valid characters
Recognized by DCE
OFF
ON
TXD input
UART
OFF
ON
Figure 30: Wake-up via data reception with further communication
Figure 30 shows the case where in addition to the wake-up character further (valid) characters are
sent. The wake-up character wakes up the module UART. The other characters must be sent after
the “wake up time” of ~20 ms. If this condition is satisfied, the module (DCE) recognizes characters.
The module will disable the UART after 2000 GSM frames from the latest data reception.
☞ The “wake-up via data reception” feature cannot be disabled.
☞ In command mode
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, if autobauding is enabled and the DTE does not implement HW flow control,
the DTE must always send a character to the module before the “AT” prefix set at the beginning
of each command line: the first character is ignored if the module is in active mode, or it represents
the wake-up character if the module is in idle mode.
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See the u-blox AT Commands Manual [2] for definitions of interface data mode, command mode and online command mode.