Quectel BC65 - Auxiliary UART Interface; UART Application

NB-IoT Module Series
BC65 Hardware Design
BC65_Hardware_Design 29 / 55
3.8.3. Auxiliary UART Interface*
The auxiliary UART interface is designed as a general-purpose UART for communication with DTE. Its
baud rates are 4800 bps, 9600 bps (default), and 57600 bps. The following is a reference design for
auxiliary UART interface.
DTE
TXD
RXD
GND
Module
AUX_TXD
AUX_RXD
GND
Figure 16: Reference Design for Auxiliary UART Interface
3.8.4. UART Application
The module provides 1.8 V UART interfaces. A level translator should be used if the application is
equipped with a 3.3 V UART interface. A level translator TXS0108EPWR provided by Texas Instruments
(visit http://www.ti.com for more information) 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
MAIN_TXD
MAIN_RXD
DBG_TXD
AUX_RXD
DBG_RXD
AUX_TXD
51 kΩ 51 kΩ
0.1 μF
0.1 μF
TXD
RXD
DBG_TXD
AUX_RXD
DBG_RXD
AUX_TXD
VDD
Level Translator
RI GPIO
Module
DTE
GND GND
Figure 17: Reference Circuit with Level Translator Chip