User's Manual

GE/GC864-QUAD V2 and GE864-GPS Hardware User Guide

1vv0300915 Rev.2 – 2011-06-15

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Reserved. Page 61 of 97

BALL

NAME

BALL

D11

TX_AUX GPS_RX

E10

F10

RX_AUX GPS_TX

GPIO4

GPS_ON_OFF

GPIO1

GPS_WAKE_UP

9.2.2. GPS Serial Port (NMEA)

This port is carrying out the GPS navigation data in NMEA 0183

format. The default configuration is 4800 bps, 8, n, 1

It is available on the following pins:

BALL

NAME

DESCRIPTION

TYPE

GPS_TX GPS TX Data (NMEA) CMOS 2.8V (GPS)

E10

GPS_RX GPS RX Data (NMEA) CMOS 2.8V (GPS)

GPS RX Lines and TX lines may need a dual supply isolation

buffer like an FXLP34 to avoid CMOS high states while in POWER

SAVING.

9.3. RS232 Level Translation

In order to interface the Telit GE/GC864-QUAD V2 AND GE864-

GPSwith a PC com port or a RS232 (EIA/TIA-232) application a

level translator is required. This level translator must

• invert the electrical signal in both directions

• change the level from 0/+3V to +15/-15V

Actually, the RS232 UART 16450, 16550, 16650 & 16750 chipsets

accept signals with lower levels on the RS232 side (EIA/TIA-

562), allowing for a lower voltage-multiplying ratio on the

level translator. Note that the negative signal voltage must

be less than 0V and hence some sort of level translation is

always required.

The simplest way to translate the levels and invert the signal

is by using a single chip level translator. There are a

multitude of them, differing in the number of driver and

receiver and in the levels (be sure to get a true RS232 level

translator not a RS485 or other standards).