User's Manual

LE940B6 Hardware User Guide

1VV0301331 Rev. 1.8 - 2017-03-15

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NOTE:

Even if USB communication is not used, it is still highly recommended to place an optional USB

connector on the application board.

At least test points of the USB signals are required since the USB physical communication is

needed in the case of SW update.

Warning:

Consider placing low-capacitance ESD protection device to protect LE940B6 against ESD strikes.

If an ESD protection should be added, the suggested connectivity is as follows:

Figure 15: ESD Protection for USB2.0

8.2. Serial Ports

The serial port is typically a secondary interface between the LE940B6 module and OEM

hardware. The following serial ports are available on the module:

• Modem Serial Port 1 (Main)

• Modem Serial Port 2 (Auxiliary)

• Modem Serial Port 3 (GNSS)

Several serial port configurations can be designed for the OEM hardware. The most common are:

• RS232 PC com port

• Microcontroller UART @ 1.8V (Universal Asynchronous Receive Transmit)

• Microcontroller UART @ 3.3V/5V or other voltages different from 1.8V

Depending on the type of serial port on OEM hardware, level translator circuits may be needed to

make the system operate. The only configuration that does not need level translation is the 1.8V

UART. The LE940B6 UART has CMOS levels as described in Section 4.3.1, 1.8V Standard GPIOs.