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FIBOCOM NL668-LA Series Hardware Guide
Page 35 of 61
5.5 UART Interface
5.5.1 UART Interface Definition
NL668-LA series module has two serial ports: the main serial port and debug serial port. The main serial
ports support 4800bps, 9600bps, 19200bps, 38400bps, 57600bps, 115200bps, 230400bps baud rate.
The default baud rate is 115200bps, used for data transmission and AT command transmission.
Debug serial port support 115200bps baud rate for FIBOCOM internal debug. Table 5-8 and table 5-9 are
the pin definition of main serial port and debug serial port.
Table 5-10 Main serial port
Pin Name
I/O
Pin No.
Description
RI
O
62
Ring indicator
DCD
O
63
Data carrier detection
CTS
O
64
Request to send
RTS
I
65
Clear to send
DTR
I
66
Data ready, sleep mode control
TXD
O
67
Module Transmit data
RXD
I
68
Module Receive data
Table 5-11 Debug serial port
Pin Name
I/O
Pin Num
Description
DBG_RXD
I
11
Module Receive data
DBG_TXD
O
12
Module Transmit data
5.5.2 UART Port Application
The serial port level of NL668-LA series module is 1.8V, if the level of the client host system is 3.3V or
other, level
translator
needed between the module and the host. The reference design circuit of level
translator is shown as follows
:
