User's Manual

GC864 Hardware User Guide

1vv0300733 Rev. 0 - 12/06/06

6 Serial Port

The serial port on the Telit GC864 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 GC864 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 GC864 UART are the

CMOS levels:

Absolute Maximum Ratings -Not Functional

Parameter Min Max

Input level on any

digital pad when on

-0.3V +3.75V

Input voltage on

analog pads 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