HUAWEI ME909u-521 LTE LGA Module
Hardware Guide
Description of the Application Interfaces
Issue 05 (2017-12-15)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
34
3.5 UART Interface
3.5.1 Overview
The ME909u-521 module provides two UART interfaces for asynchronous
communication channels. They are UART0 (4-wire UART) and UART1 (4-wire UART),
which work as high speed UART by default.
The UART2 (2-wire UART) is for debugging only. Customers should layout two test
points for them in case of system trouble shooting and analysis.
Table 3-6 lists the UART interface signals.
Table 3-6
UART interface signals
Pin
No.
Pin Name
Pad
Type
Description
Parameter
Min.
(V)
Typ.
(V)
Max.
(V)
Comments
1
UART1_TX
O
UART1 transmit
output
V
OH
1.35
1.8
1.8
-
V
OL
0
-
0.45
-
2
UART1_RTS
O
UART1 Ready for
receive
V
OH
1.35
1.8
1.8
-
V
OL
0
-
0.45
-
3
UART1_CTS
I
UART1 Clear to Send V
IH
1.17
1.8
2.1
V
IL
–0.3
-
0.63
-
4
UART1_RX
I
UART1 receive data
input
V
IH
1.17
1.8
2.1
-
V
IL
–0.3
-
0.63
-
28
UART2_TX
O
UART2 transmit
output
V
OH
1.35
1.8
1.8
-
V
OL
0
-
0.45
-
29
UART2_RX
I
UART2 receive data
input
V
IH
1.17
1.8
2.1
-
V
IL
–0.3
-
0.63
-
74
UART0_RTS
O
UART0 Ready for
receive
V
OH
1.35
1.8
1.8
-
V
OL
0
-
0.45
-
76
UART0_TX
O
UART0 transmit
output
V
OH
1.35
1.8
1.8
-
V
OL
0
-
0.45
-
78
UART0_RX
I
UART0 receive data
input
V
IH
1.17
1.8
2.1
-
V
IL
–0.3
-
0.63
80
UART0_CTS
I
UART0 Clear to Send V
IH
1.17
1.8
2.1
-
V
IL
–0.3
-
0.63
-
