User's Manual

LE910 V2 HARDWARE USER GUIDE 1VV0301200 Rev.2 Preliminary • 2015-08-04 43 of 81
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5.5.3 Serial Ports
The LE910 V2 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 LE910 V2 the ports are CMOS 1.8.
5.5.3.1 Modem serial port 1 (USIF0)
The serial port 1 on the LE910 V2 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 LE910 V2 that indicates
the carrier presence
2
C104/RXD
M15
Transmit line *see Note
Output transmit line of LE910 V2 UART
3
C103/TXD
N15
Receive line *see Note
Input receive of the LE910 V2 UART
4
C108/DTR
M14
Data Terminal Ready
Input to the LE910 V2 that controls the
DTE READY condition
5
GND
M12,
B13,
P13,
E14 …
Ground
Ground
6
C107/DSR
P14
Data Set Ready
Output from the LE910 V2 that indicates
the module is ready
7
C106/CTS
P15
Clear to Send
Output from the LE910 V2 that controls
the Hardware flow control
8
C105/RTS
L14
Request to Send
Input to the LE910 V2 that controls the
Hardware flow control
9
C125/RING
R14
Ring Indicator
Output from the LE910 V2 that indicates
the incoming call condition