Installation Instructions

LISA-U2 series - System Integration Manual
UBX-13001118 - R19 Early Production Information System description
Page 55 of 175
1.9.2.1 UART features
All flow control handshakes are supported by the UART interface and can be set by appropriate AT commands
(see u-blox AT Commands Manual [2], &K, +IFC, \Q AT commands): hardware flow control (RTS/CTS), software
flow control (XON/XOFF), or none flow control.
Hardware flow control is enabled by default.
One-shot autobauding is supported: the baud rate detection is performed once, at module start up. Then the
module works at the fixed baud rate (the detected one) and the baud rate can only be changed via the
appropriate AT command (+IPR, for more details see the u-blox AT Commands Manual [2]). In particular:
 If automatic baud rate detection is configured in the active memory profile, the baud rate is detected once
at the module power-on
 The factory-programmed setting enables the automatic baud rate detection (<rate> value is 0)
Since autobauding is implemented as “one shot” autobauding, any setting of +IPR=0 should be avoided; the
only exception is if the baud rate is fixed in the stored NVRAM profile. In this case, the module starts without
autobauding and the host needs to reactivate it.
If the system starts in autobauding (i.e. the +IPR is 0), the first “at” sequence provided to the module detects the
baud rate. For example the first command sent from the DTE at any rate can be: AT+CPIN="1234".Characters
different than “AT” are ignored during the baud rate detection since the “at” or “AT” sequence triggers the
hardware detection sequence. “At” or “aT” sequences are invalid: both detection characters must be lowercase
or uppercase.
The module generates a response for the DTE once autobauding detection is successful, the command is
accepted and the command response is available. Therefore, even if the detection was previously successful, it is
only possible to assume that the detection phase was successful after a response.
If the DTE does not receive any response after some time, it must retry (the timeout value should be adjustable
inside the DTE application). In any case, use a very simple command as the first command, for which the
execution time is short and almost constant (e.g. ATE). Note that the only way to recover from a detection failure
is the detection reattempt, since the AT interface is only available after a successful detection.
One-shot autobauding is enabled by factory programmed setting.
The only way to recover from a detection failure is the detection reattempt, since the AT interface is only
available after a successful detection.
The following baud rates can be configured by AT command:
 1200 b/s
 2400 b/s
 4800 b/s
 9600 b/s
 19200 b/s
 38400 b/s
 57600 b/s
 115200 b/s, default value when the one-shot autobauding is disabled
 230400 b/s
 460800 b/s
 921600 b/s
460800 b/s and 921600 b/s baud rates cannot be automatically detected by one-shot autobauding.