Fibocom LC116-LA, Руководство по оборудованию, Страница: 47 / 76

4 Circuit Design
Copyright © Fibocom Wireless Inc. 45
The ESD protector for the USB data cable must be placed close to the USB interface. The
parasitic capacitance of the ESD protector must not exceed 1 pF.
USB 2.0 differential signal cable should be laid on the signal layer nearest to the ground.
For more information about the USB 2.0 specification, please visit
http://www.usb.org/home
4.4.2 UART
The module has a main serial port, a Bluetooth serial port* for data communication and a
debugging serial port.

The main serial port supports baud rates of 4800 bps, 9600 bps, 19200 bps, 38400
bps, 57600 bps, 115200 bps, 230400 bps, 460800 bps and 921600 bps. The default
baud rate is 115200 bps, used for data transmission and AT command transmission.

The Bluetooth serial port* supports baud rates of 4800 bps, 9600 bps, 19200 bps,
38400 bps, 57600 bps, 115200 bps, 230400 bps, 460800 bps and 921600 bps. The
default baud rate is 115200 bps, used for Bluetooth data communication.

The debugging serial interface supports 115200 bps baud rate. It is used for Linux
control and log output.
The serial port level of the LC116-LA series module is 1.8 V. If the level of the host system
is 3.3 V or another value, a level converter is needed between the module and the host.
Figure 15 and Figure 16 show the design of reference circuit of the serial port level
conversion chip. You can design the input and output circuits of the dashed line part by
referring to the solid line part in Figure 16, but pay attention to the connection direction.