Product Info

NB-IoT Module Series
BC660K-GL Hardware Design
BC660K-GL_Hardware_Design
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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 the 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.
If the voltage domain of the customer application system is 1.8 V, VIO_SEL can be floating; If the voltage
domain of the customer application system is 3.3 V, VIO_SEL can be grounded.
The following figure shows the reference circuit design:
Figure 13: Reference Circuit Design of UART
The following circuit shows a reference design for the communication between the module and a PC with
standard RS-232 interface. Make sure to select appropriate voltage domain through VIO_SEL according
to the actual situation.