Telit GM862-QUAD/-QUAD-PY
Hardware User Guide
1vv0300692, Rev. ISSUE#0, - 04/10/2005
Reproduction forbidden without DAI Telecom written authorization – All Right reserved – Right of modification reserved
page 17 of 69
4 Serial Port
The serial port on the Telit GM862-QUAD is the core of the interface between the module and
OEM hardware. Several configurations can be designed for the serial port on the OEM hardware,
but the most common are:
- RS232 PC com port
- microcontroller UART @ 2.8V - 3V (Universal Asynchronous Receive Transmit)
- microcontroller UART@ 5V or other voltages different from 2.8V
Depending from the type of serial port on the OEM hardware a level translator circuit may be
needed to make the system work. The only configuration that doesn't need a level translation is the
2.8V UART.
The serial port on the GM862-QUAD is a +2.8V UART with all the 7 RS232 signals. It differs
from the PC-RS232 in the signal polarity (RS232 is reversed) and levels. The levels for the GM862-
QUAD UART are the CMOS levels:
Absolute Maximum Ratings -Not Functional
Parameter Min
Max
Input level on any
digital pin when on
-0.3V +3.75V
Input voltage on
analog pins when on
-0.3V +3.0
V
Operating Range - Interface levels (2.8V CMOS)
Level Min
Max
Input high level V
IH
2.1V 3.3V
Input low level V
IL
0V
0.5V
Output high level V
OH
2.2V 3.0V
Output low level V
OL
0V 0.35V
