u-blox LEXI-R422, Руководство по системной интеграции

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LEXI-R422 - System integration manual
UBX-23007449 - R02 System description Page 28 of 108
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1.9.1 UART interfaces
1.9.1.1 UART features
LEXI-R422 modules include a primary UART interface (UART) for communication with an application
host processor, supporting AT commands, data communication, multiplexer protocol functionality
(see
1.9.1.3 ), and FW update by means of FOAT, with settings configurable by dedicated AT
commands (for more details, see the AT commands manual [2] ):
•
8-wire serial port with RS-232 functionality conforming to ITU-T V.24 recommendation [5] , with
CMOS compatible signal levels (0 V for low data bit / ON state, 1.8 V for high data bit / OFF state)
o
Data lines ( RXD as data output, TXD as data input)
o
HW flow control lines ( CTS as flow control output, RTS as flow control input)
o
Modem status and control lines ( DTR input, DSR output, DCD output, RI output) 2
☞
UART signal names of LEXI-R422 modules conform to the ITU-T V.24 [5] : e.g. TXD line represents
data transmitted by the DTE (host processor output) and received by the DCE (module input).
LEXI-R422 modules include an auxiliary UART interface (UART AUX) for communication with an host
processor, supporting AT commands, data, GNSS tunneling, FW update by means of FOAT, with
settings configurable by dedicated AT commands (for details, see the AT commands manual
[2] ):
• 4-wire serial port with RS-232 functionality conforming to ITU-T V.24 recommendation [5] , with
CMOS compatible signal levels (0 V for low data bit / ON state, 1.8 V for high data bit / OFF state)
o
Data lines ( DCD as data output, DTR as data input)
o
HW flow control lines ( RI as flow control output, DSR as flow control input)
LEXI-R422 modules UART interface is by default configured in AT command mode: the module waits
for AT command instructions and interprets all the characters received as commands to execute. The
functionalities supported by the modules can be in general set and configured by AT commands:
• AT commands according to 3GPP TS 27.007 [6] , 3GPP TS 27.005 [7] , 3GPP TS 27.010 [8]
• u-blox AT commands (see the AT commands manual [2] )
The default baud rate is 115200 b/s. The default frame format is 8N1 (8 data bits, no parity, 1 stop
bit: see
Figure 15 ). Baud rates can be configured by AT command (see the AT commands manual [2] ).
☞
Automatic baud rate detection and automatic frame format recognition are not supported.
D0 D1 D2 D3 D4 D5 D6 D7
Start of 1-Byte
transfer
Start Bit
(Always 0)
Possible Start of
next transfer
Stop Bit
(Always 1)
t
bit
= 1/(Baudrate)
Normal Transfer, 8N1
Figure 15: UART 8N1 frame format (8 data bits, no parity, 1 stop bit)
1.9.1.2 UART signals behavior
At the end of the module boot sequence (see Figure 11 ), the module is by default in active mode, and
the UART interface is initialized and enabled as AT commands interface.
2 DTR , DSR , DCD and RI pins can be alternatively configured, in mutually exclusive way, as auxiliary UART interface (UART AUX).