User's Manual

UE910 3G HARDWARE USER GUIDE 1vv0301171 Rev.3 • 2015-04-17 42 of 78
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Serial Ports
The UE910 module is provided with by 2 Asynchronous serial ports:
 MODEM SERIAL PORT 1 (Main)
 MODEM SERIAL PORT 2 (Auxiliary)
Several configurations can be designed for the serial port on the OEM hardware, but the most common
are:
 RS232 PC com port
 microcontroller UART @ 1.8V (Universal Asynchronous Receive Transmit)
 microcontroller UART @ 5V or other voltages different from 1.8V
Depending from the type of serial port on the OEM hardware a level translator circuit may be needed to
make the system work.
On the UE910 the ports are CMOS 1.8.
MODEM SERIAL PORT 1 (USIF0)
The serial port 1 on the UE910 is a +1.8V UART with all the 7 RS232 signals.
It differs from the PC-RS232 in the signal polarity (RS232 is reversed) and levels.
The following table is listing the available signals:
RS232
Pin
Signal
Pad
Name
Usage
1
C109/DCD
N14
Data Carrier Detect
Output from the UE910 that indicates
the carrier presence
2
C104/RXD
M15
Transmit line *see Note
Output transmit line of UE910 UART
3
C103/TXD
N15
Receive line *see Note
Input receive of the UE910 UART
4
C108/DTR
M14
Data Terminal Ready
Input to the UE910 that controls the DTE
READY condition
5
GND
M12,
B13,
P13,
E14 …
Ground
Ground
6
C107/DSR
P14
Data Set Ready
Output from the UE910 that indicates
the module is ready
7
C106/CTS
P15
Clear to Send
Output from the UE910 that controls the
Hardware flow control
8
C105/RTS
L14
Request to Send
Input to the UE910 that controls the
Hardware flow control
9
C125/RING
R14
Ring Indicator
Output from the UE910 that indicates
the incoming call condition