User's Manual

LE910 Hardware User Guide
1vv0301089 Rev.7 – 25-10-2015
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved page 55 of 88
11 Serial Ports
The LE910 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 the ports are CMOS 1.8.
The electrical characteristics of the Serial ports are explained in the following tables:
Absolute Maximum Ratings -Not Functional
Parameter
Min
Max
Input level on any digital pin (CMOS 1.8) with
respect to ground
-0.3V
2.16V
Operating Range - Interface levels (1.8V CMOS)
Level
Min
Max
Input high level
1.5V
2.1V
Input low level
0V
0.5V
Output high level
1.35V
1.8
Output low level
0V
0.45V