User Manual

GM862-QUAD / PY Hardware User Guide

1vv0300748 Rev. 5 - 20/09/07

7 Serial Ports

The serial port on the Telit GM862-QUAD / PY is the core of the interface between the module and

OEM hardware.

2 serial ports are available on the module:

• MODEM SERIAL PORT

• TRACE (Usable only on GM862-QUAD-PY for Python Debug)

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 TRACE Serial Port is a 3 wire (RX, TX GND) +2.8V UART.

The MODEM serial port on the GM862-QUAD / PY 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 / PY UART are the CMOS levels:

Absolute Maximum Ratings -Not Functional

Parameter Min Max

Input level on any

digital pin when on

-0.3V +3.6V

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

2.1V 3.3V

Input low level V

0V 0.5V

Output high level V

2.2V 3.0V

Output low level V

0V 0.35V