Circuit Recommended For The Uart Interface; Usb Interface - Huawei ME909u-521 Hardware Manual

HUAWEI ME909u-521 LTE LGA Module
Hardware Guide

3.5.2 Circuit Recommended for the UART Interface

Figure 3-14 Connection of the UART interface in the ME909u-521 module (DCE) with
the host (DTE)
The RS-232 chip can be used to connect the ME909u-521 module with UART. In this
connection, the Complementary Metal Oxide Semiconductor (CMOS) logic level and
the Electronic Industries Association (EIA) level are converted mutually. For example,
it is recommended that you use the MAX218 chip (The MAX218's max baud is
120000 bit/s) with a 2-wire serial port.

3.6 USB Interface

The ME909u-521 module is compliant with USB 2.0 High speed protocol. The USB
interface is powered directly from the VBAT supply. The USB signal lines are
compatible with the USB 2.0 signal specifications. Figure 3-15 shows the circuit of the
USB interface.
Table 3-7 Definition of the USB interface
Pin Pin Name
No.
85 USB_DM
Issue 05 (2017-12-15)
It is recommended that customer set the pins related to UART interface as test points on the

DTE board for debugging.
The level of RS-232 Transceivers must match that of the ME909u-521 module.

Pad Description
Type
I/O USB Data- defined in
the USB 2.0
Specification
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
Description of the Application Interfaces
Parameter Min. Typ.
(V) (V)
- - -
Max. Comments
(V)
- -
35