Telit Wireless Solutions GE864 manual RS232 level translation

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GE864 Hardware User Guide

1vv0300694 Rev.10 - 10/06/08

8.2 RS232 level translation

In order to interface the Telit GE864 with a PC com port or a RS232 (EIA/TIA-232) application a level translator is required. This level translator must

ƒinvert the electrical signal in both directions

ƒchange 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).

By convention the driver is the level translator from the 0-3V UART level to the RS232 level, while the receiver is the translator from RS232 level to 0-3V UART.

In order to translate the whole set of control lines of the UART you will need:

ƒ5 driver

ƒ3 receiver

NOTE: The digital input lines working at 2.8VCMOS have an absolute maximum input voltage of 3,75V; therefore the level translator IC shall not be powered by the +3.8V supply of the module. Instead it shall be powered from a +2.8V / +3.0V (dedicated) power supply.

This is because in this way the level translator IC outputs on the module side (i.e. GE864 inputs) will work at +3.8V interface levels, stressing the module inputs at its maximum input voltage.

This can be acceptable for evaluation purposes, but not on production devices.

NOTE: In order to be able to do in circuit reprogramming of the GE864 firmware, the serial port on the Telit GE864 shall be available for translation into RS232 and either it’s controlling device shall be placed into tristate, disconnected or as a gateway for the serial data when module reprogramming occurs.

Only RXD, TXD, GND and the On/off module turn on pad are required to the reprogramming of the module, the other lines are unused.

All applicator shall include in their design such a way of reprogramming the GE864.

Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved

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Contents GE864 Hardware User Guide This document is relating to the following products GE864 Hardware User GuideContents 10.4 10.110.2 10.3Packing system Safety RecommandationsDisclaimer GE864-QUAD / PY OverviewLength 30 mm Width Thickness GE864 Mechanical DimensionsPIN-OUT GE864 module connectionsGpio Reserved Vbatt TOP View BGA Balls LayoutReserved Turning on the GE864-QUAD / PY Hardware Commands10k Hardware Unconditional Restart Turning OFF the GE864-QUAD / PYHardware shutdown 10k Power Supply Requirements Power SupplyElectrical Design Guidelines General Design Rules1.2 + 12V input Source Power Supply Design Guidelines GE864 Hardware User Guide Battery Source Power Supply Design Guidelines Battery Charge control Circuitry Design Guidelines GE864 Hardware User Guide Thermal Design Guidelines Power Supply PCB layout Guidelines GSM Antenna Requirements AntennaAntenna Line on PCB Requirements GSM Antenna PCB line GuidelinesGSM Antenna Installation Guidelines Operating Range Interface levels 2.8V Cmos Logic level specificationsCurrent characteristics Absolute Maximum Ratings -Not FunctionalSignal Min Max Reset signalSignal Function Bga Ball Operating Range Interface levels 2.8V Cmos Level Min Max Serial PortsAbsolute Maximum Ratings -Not Functional ParameterMin Max Signals of the GE864 serial port are RS232 level translation GE864 Hardware User Guide 5V Uart level translation GE864 Hardware User Guide External Amplifier Audio Section OverviewShort description Input Lines MicrophoneMicmt 1st differential microphone path Input Lines CharacteristicsOutput Lines Speaker External SIM Holder Implementation Output Lines CharacteristicsOnoff General Purpose I/OPict01 Operating Range Interface levels 1.8V Cmos Level Min Max Gpio Logic levelsAbsolute Maximum Ratings -Not Functional Parameter Min Max Using a Gpio Pad as Output Using a Gpio Pad as InputUsing the Alarm Output GPIO6 Using the RF Transmission Control GPIO4Using the Rftxmon Output GPIO5 AT#SRP=3 Using the Buzzer Output GPIO7Magnetic Buzzer Concepts Working Current Influence Power Supply InfluenceFrequency Behaviour Allowed Gpio Using the Temperature Monitor FunctionLED status Device Status Indication of network service availabilityRTC Bypass out VAUX1 power outputMin Max Units DAC and ADC sectionDAC Converter DescriptionLow Pass Filter Example Command is AT#DAC=enable,valueEnabling DAC ADC Converter Using ADC Converter12.1General Module finishing & dimensionsMounting the GE864 on your Board Top View Recommended foot print for the application GE864Top View Suggested Inhibit AreaStencil Debug of the GE864 in productionMetal pad diameter B mm PCB pad designBall pitch mm Solder resist opening diameter a mm Solder paste Sn/Ag/Cu Solder pasteFinish Layer thickness µm Properties Lead freeFollowing is the recommended solder reflow profile 12.1.8 GE864 Solder reflowPacking system 12.2.1 GE864 orientation on the tray Moisture sensibility Conformity Assessment Issues Safety Recommandations Revision Date Changes Document Change Log

GE864 specifications

The Telit Wireless Solutions GE864 is a compact yet robust cellular module designed for a wide range of M2M (Machine-to-Machine) applications. As part of the Telit family, the GE864 is particularly notable for its small form factor, reliability, and versatility, making it an ideal choice for various industries including automotive, healthcare, and utilities.

One of the standout features of the GE864 is its integrated GPRS capabilities, allowing devices to connect to cellular networks seamlessly. With a maximum data rate of 85.6 kbps for downlink and 42.8 kbps for uplink, this module facilitates efficient data transmission, suitable for applications that require real-time data monitoring and control.

The GE864 supports multiple frequency bands, ensuring global compatibility. It can operate on GSM/GPRS networks, enhancing its usability across different regions. This multi-band support allows developers to deploy their solutions in diverse markets without modifying the hardware, thus saving both time and resources.

Power management is another critical area where the GE864 shines. The module comes equipped with advanced power-saving features, allowing it to operate effectively in battery-powered applications. Notable features include sleep modes and intelligent power management protocols that help extend battery life while maintaining reliable connectivity.

In terms of physical specifications, the GE864 has a compact design, measuring only 29x38 mm, which is essential for integration into space-constrained environments. This makes it particularly well-suited for applications in remote monitoring, asset tracking, and utility metering.

The module supports a range of interfaces, including UART, USB, and I2C, providing developers with the flexibility to connect various peripheral devices and sensors. This versatility enables the creation of customized solutions tailored to specific application needs.

Furthermore, the GE864 is designed to meet rigorous quality and durability standards, making it suitable for use in harsh environments. Its resilience to extreme temperatures and vibrations ensures dependable performance in challenging conditions, which is often a requirement in industrial and automotive applications.

In summary, the Telit Wireless Solutions GE864 is a feature-rich cellular module that combines compact design with robust performance and versatility. Its advanced connectivity options, efficient power management, and reliable operation make it an invaluable asset for businesses looking to develop innovative M2M solutions. Whether it’s for smart cities, telematics, or healthcare applications, the GE864 is engineered to meet the demands of today's connected world.
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