NB-IoT Module Series
BC66 Hardware Design
BC66_Hardware_Design 27 / 50
DTE
TXD
RXD
GND
Module
TXD_AUX
RXD_AUX
GND
Figure 14: Reference Design for Auxiliary UART Port
3.8.4. UART Application
The module provides 1.8V UART interfaces. A level translator should be used if the application is
equipped with a 3.3V UART interface. A level translator TXS0108EPWR provided by
Texas Instruments
is
recommended. The following figure shows a reference design.
VCCA
VCCB
OE
A1
A2
A3
A4
A5
A6
A7
A8
GND
B1
B2
B3
B4
B5
B6
B7
B8
VDD_EXT
TXD
RXD
TXD_DBG
RXD_AUX
RXD_DBG
TXD_AUX
51K
51K
0.1uF
0.1uF
TXD
RXD
TXD_DBG
RXD_AUX
RXD_DBG
TXD_AUX
VDD
Translator
RI
GPIO
Module
DTE
GND
GND
Figure 15: Reference Circuit with Translator Chip
Please visit http://www.ti.com for more information.
Another example with transistor translation circuit is shown as below. The circuit design of dotted line
section can refer to the design of solid line section, in terms of both module input and output circuit
designs, but please pay attention to the direction of connection.
