Quectel BC660K-GL - UART Application

NB-IoT Module Series
BC660K-GL Hardware Design
BC660K-GL_Hardware_Design 28 / 57
DTE
TXD
RXD
GND
Module
DBG_TXD
DBG_RXD
GND
Figure 12: Reference Design for Debug UART Port
3.7.3. UART Application
The serial port voltage domain of this module is optional. Customers can select the appropriate voltage
domain through VIO_SEL according to actual situation. When VIO_SEL is floating, the VDD_EXT voltage
domain is 1.8 V; when VIO_SEL is grounded, the VDD_EXT voltage domain is 3.3 V or equals the VBAT
voltage
1)
.
If the voltage domain of your application system is 1.8 V, VIO_SEL can be floating; If the voltage domain
of your application system is 3.3 V, VIO_SEL must be grounded.
The following figure shows the reference design of UART:
VDD_EXT
MAIN_TXD
RI
DBG_TXD
MAIN_RXD
GPIO
RXD_DTE
TXD_DTE
RXD_DBG
VDD
DBG_RXD
TXD_DBG
Module
DTE
GND GND
VIO_SEL
0 Ω
R1
R2
R3
1 kΩ
1 kΩ
1 kΩ
1 kΩ
1 kΩ
R4
R5
R6
VDD_EXT
VDD_DTE
RESET_N
GND
BOOTBOOT
VBAT
VBAT
RESET_N
MAIN_RXD MAIN_TXD
TEST POINTS
Figure 13: Reference Design for UART
The following circuit shows a reference design for the communication between the module and a PC with
a standard RS-232 interface. Make sure to select appropriate voltage domain through VIO_SEL