Telit Wireless Solutions GE864 manual Serial Ports

GE864 Hardware User Guide

1vv0300694 Rev.10 - 10/06/08

8 Serial Ports

The serial port on the Telit GE864-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

•MODEM SERIAL PORT 2 (DEBUG)

8.1 MODEM SERIAL PORT

Several configurations can be designed for the serial port on the OEM hardware, but the most common are:

•RS232 PC com port

•Micro controller UART @ 2.8V – 3V (Universal Asynchronous Receive Transmit)

•Micro controller 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 GE864-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 GE864- QUAD/PY UART are the CMOS levels:

Absolute Maximum Ratings –Not Functional

ParameterMin Max

Input level on any	-0.3V	+3.6V
digital pad when on
Input voltage on	-0.3V	+3.0 V
analog pads when on

Operating Range – Interface levels (2.8V CMOS)

Level		Min	Max
Input high level	VIH	2.1V	3.3V
Input low level	VIL	0V	0.5V
Output high level VOH		2.2V	3.0V
Output low level	VOL	0V	0.35V

Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved page 33 of 69