ATA5781/ATA5782/ATA5783 [SUMMARY DATASHEET]

9286FS–RKE–08/14

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The impedance of the SAW filter is transformed with LC matching circuits to the SPDT_ANT port and also to the antenna. An

load capacitors for this crystal are integrated, to reduce system part count and cost. Only three supply blocking capacitors

are needed to decouple the different supply voltages AVCC, DVCC and VS of the Atmel ATA5781/2/3. The exposed die pad

is the RF and analog ground of the Atmel ATA5781/2/3. It is directly connected to AGND via a fused lead. For applications

operating in the 868.3MHz or 915MHz frequency bands, a High-Band RF input is supplied, RFIN_HB, and must be used

instead of RFIN_LB. The Atmel ATA5781/2/3 is controlled using specific SPI commands via the SPI interface and an internal

EEPROM for application specific configuration. This application is compatible to the Atmel ATA5831/2/3, therefore, the same

application board can be used for both devices, just the population of the TX path is not required for the Atmel ATA5781/2/3..

2.

System Functional Description

2.1

Overview

2.1.1

Service-based Concept

The Atmel ATA5781/2/3 is a highly configurable UHF receiver. The configuration is stored in an internal 1024-byte

EEPROM. The master system control is performed by firmware. General chip-wide settings are loaded from the EEPROM to

hardware registers during system initialization. During start-up of a receive mode the specific settings are loaded from the

EEPROM or SRAM to the current service in the SRAM and from there to the corresponding hardware registers.

A complete configuration set of the receiver is called “service” and includes RF settings, demodulation settings, and

telegram handling information. Each service contains three channels which differ in the RF receive frequencies.

The Atmel ATA5781/2/3 supports five services which can be configured in various ways to meet customer requirements.

Three service configurations are located in the EEPROM space. They are fixed configurations which should not be changed

during runtime.

Two service configurations are located in the SRAM space and can be modified by USER SW in a Flash application or by an

SPI command during IDLEMode.

A service consists of

●

One service-specific configuration part

●

Three channel-specific configuration parts

Further configurations for PollingMode and RSSI are available and can be modified in IDLEMode via an SPI command

and/or User SW.

Figure 2-1 on page 9 gives an overview on the service based-concept.