Atmel ATA5781/ATA5782/ATA5783 UHF ASK/FSK Receiver SUMMARY DATASHEET Features ● AVR microcontroller core with 1Kbyte SRAM and 24Kbyte RF library in firmware (ROM) ● Atmel® ATA5781: 20Kbyte of user Flash ● Atmel ATA5782: 20Kbyte of user ROM ● Atmel ATA5783: No user memory — RF library in firmware only ● Supported frequency ranges ● Low-Band 310MHz to 318MHz, 418MHz to 477MHz ● High-Band 836MHz to 956MHz ● 315.00MHz/433.92MHz/868.30MHz and 915.00MHz with one 24.305MHz crystal ● Low current consumption ● 9.8mA for RXMode (Low-Band), 1.2mA for 21ms cycle three-channel polling ● Typical OFFMode current of 5nA (maximum 600nA at Vs = 3.6V and T = 85°C) ● Supports the 0dBm class of ARIB STD-T96 ● Input 1dB compression point ● –48dBm (full sensitivity level) ● –20dBm (active antenna damping) ● Programmable channel frequency with fractional-N PLL ● 93Hz resolution for Low-Band ● 185Hz resolution for High-Band ● FSK deviation ±0.375kHz to ±93kHz ● FSK sensitivity (Manchester coded) at 433.92MHz ● ● ● ● –108.5dBm at 20Kbit/s –111dBm at 10Kbit/s –114dBm at 5Kbit/s –122.5dBm at 0.75Kbit/s f = ± 20kHz f = ± 10kHz f = ± 5kHz f = ± 0.75kHz BWIF = 165kHz BWIF = 165kHz BWIF = 165kHz BWIF = 25kHz ● ASK sensitivity (Manchester coded) at 433.92MHz ● –110.5dBm at 20Kbit/s ● –125dBm at 0.5Kbit/s This is a summary document. The complete document is available under NDA. For more information, please contact your local Atmel sales office. ● ● ● BWIF = 80kHz BWIF = 25kHz Programmable Rx-IF bandwidth 25kHz to 366kHz (approximately 10% steps) Blocking (BWIF = 165kHz): 64dBc at frequency offset = 1MHz and 48dBc at 225kHz High image rejection: 55dB at 315MHz/433.92MHz and 47dB at 868.3MHz/915MHz without calibration 9286BS–RKE–06/13 ● ● ● Supported data rate in buffered mode 0.5Kbit/s to 80Kbit/s (120Kbit/s NRZ) Supports pattern-based wake-up and start of frame identification Flexible service configuration concept with on-the-fly (OTF) modification (in IDLEMode) of SRAM service parameters (data rate, …) ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● Each service consists of ● One service-specific configuration part ● Three channel-specific configuration parts ● Three service configurations are located in EEPROM ● Two service configurations are located in SRAM and can be modified via SPI or embedded application software Digital RSSI with very high relative accuracy of ±1dB thanks to digitized IF processing Programmable clock output derived from crystal frequency 1024byte EEPROM data memory for receiver configuration SPI interface for Rx data access and receiver configuration 500Kbit SPI data rate for short periods on SPI bus and host controller On demand services (SPI or API) without polling or telegram reception Integrated temperature sensor Self check and calibration with temperature measurement Configurable EVENT signal indicates the status of the IC to an external microcontroller Automatic low-power channel polling Flexible polling configuration concerning timing, order and participating channels Fast reaction time Power-up (typical 1.5ms, OFFMode -> RXMode) Supports mixed ASK/FSK telegrams Non-byte aligned data reception Software customization Antenna diversity with external switch via GPIO control Antenna diversity with internal SPDT switch Supply voltage ranges 1.9V to 3.6V and 2.4V to 5.5V Temperature range –40°C to +105°C ESD protection at all pins (±4kV HBM, ±200V MM, ±750V FCDM) Small 55mm QFN32 package/pitch 0.5mm Backward package and pin-to-pin compatibility with Atmel® ATA5780N Backward RF matching compatibility with Atmel ATA5780N (RF redesign not needed) Suitable for applications governed by EN 300 220 and FCC part 15, title 47 Atmel ATA5781 [Summary DATASHEET] 9286BS–RKE–06/13 2 1. General Product Description 1.1 Introduction The Atmel® ATA5781/2/3 is a highly integrated, low-power UHF ASK/FSK RF receiver with an integrated AVR microcontroller. It is package and pin-to-pin compatible with the previous generation of RF devices (Atmel ATA5830N, ATA5831/2/3 and Atmel ATA5780N). The Atmel ATA5781/2/3 is partitioned into three sections; an RF front end, a digital baseband and the low-power 8-bit AVR microcontroller. The product is designed for the ISM frequency bands in the ranges of 310MHz to 318MHz, 418MHz to 477MHz and 836MHz to 956MHz. The external part count is kept to a minimum due to the very high level of integration in this device. By combining outstanding RF performance with highly sophisticated baseband signal processing, robust wireless communication can be easily achieved. The receive path uses a low-IF architecture with an integrated double quadrature receiver and digitized IF processing. This results in high image rejection and excellent blocking performance. In addition, highly flexible and configurable baseband signal processing allows the receiver to operate in several scanning, wake-up and automatic self-polling scenarios. For example, during polling the IC can scan for specific message content (IDs) and save valid telegram data in the FIFO buffer for later retrieval. The device integrates two receive paths that enable a parallel search for two telegrams with different modulations, data rates, wake-up conditions, etc. The Atmel ATA5781/2/3 implements a flexible service configuration concept and supports up to 15 channels. The channels are grouped into five service configurations with three channels each. Three service configurations are located in the EEPROM. Two service configurations are located in the SRAM to allow on-the-fly modifications during IDLEMode via SPI commands or application software. The application software is located in the Flash for Atmel ATA5781 or in the ROM for Atmel ATA5782. Highly configurable and autonomous scanning capability enables flexible polling scenarios with up to 15 channels. The configuration of the receiver is stored in a 1024byte EEPROM. The SPI interface enables external control and device reconfiguration. Table 1-1. Program Memory Comparison of Atmel ATA5781/2/3 Devices Device Atmel Firmware ROM User Flash User ROM Atmel ATA5781 24Kbyte 20Kbyte - Atmel ATA5782 24Kbyte - 20Kbyte Atmel ATA5783 24Kbyte - - In the Atmel ATA5781 the internal microcontroller with 20Kbyte user Flash can be used to add custom extensions to the Atmel firmware. The Atmel ATA5782 provides 20Kbyte user ROM as a replacement for the 20Kbyte Flash for high-volume applications. The Atmel ATA5783 embeds only the firmware ROM without user memory. The debugWIRE and ISP interface are available for programming purposes. Compatibility to the Atmel ATA5780N, Atmel ATA5830N and Atmel ATA5831/2/3 The Atmel ATA5781/2/3 is pin-to-pin compatible with the Atmel ATA5830N transceiver, the Atmel ATA5780N receiver and the Atmel ATA5831/2/3 transceivers. The Rx performance of the receivers matches that of the transceivers. Atmel ATA5781 [Summary DATASHEET] 9286BS–RKE–06/13 3 System Overview Figure 1-1. Circuit Overview SRC, FRC Oscillators Supply Reset AVR CPU EEPROM Flash Rx DSP ROM RF Front End SRAM RFIN AVR Peripherals 1.2 DATA BUS XTO XTAL Port B (8) Port C (6) PB[7..0] (SPI) PC[5..0] Figure 1-1 shows an overview of the main functional blocks of the Atmel® ATA5781/2/3. External control of the Atmel ATA5781/2/3 is performed through the SPI pins SCK, MOSI, MISO, and NSS on port B. The configuration of the Atmel ATA5781/2/3 is stored in the EEPROM and a large portion of the functionality is defined by the firmware located in the ROM and processed by the AVR. An SPI command can trigger the AVR to configure the hardware according to settings that are stored in the EEPROM and start up a given system mode (e.g., RXMode, or PollingMode). Internal events such as “Start of Telegram” or “FIFO empty” are signaled to an external microcontroller on pin 28 (PB6/EVENT). During the start-up of a service, the relevant part of the EEPROM content is copied to the SRAM. This allows faster access by the AVR during the subsequent processing steps and eliminates the need to write to the EEPROM during runtime because parameters can be modified directly in the SRAM. As a consequence the user does not need to observe the EEPROM read/write cycle limitations. It is important to note that all PWRON and NPWRON pins (PC1..5, PB4, PB7) are active in OFFMode. This means that even if the Atmel ATA5781/2/3 is in OFFMode and the DVCC voltage is switched off, the power management circuitry within the Atmel ATA5781/2/3 biases these pins with VS. AVR ports can be used as button inputs, external LNA supply voltage (RX_ACTIVE), LED drivers, EVENT pin, switching control for additional SPDT switches, general purpose digital inputs, or wake-up inputs, etc. Some functionality of these ports is already implemented in the firmware and can be activated by adequate EEPROM configurations. Other functionality is available only through custom software residing in the 20Kbyte Flash program memory (Atmel ATA5781) or in the 20Kbyte user ROM program memory (Atmel ATA5782). Atmel ATA5781 [Summary DATASHEET] 9286BS–RKE–06/13 4 Pinning ATEST_IO2 AGND PB7 PB6 PB5 PB4 PB3 32 31 30 29 28 27 26 25 1 NC 5 SPDT_RX2 6 NC 7 VS_SPDT 8 9 10 11 12 13 14 Note: The exposed die pad is connected to the internal die. Table 1-2. Pin Description 15 16 PC2 4 PC1 SPDT_ANT Atmel ATA5781 ATA5782 ATA5783 PC0 3 VS SPDT_RX AVCC 2 XTAL2 RFIN_HB exposed die pad XTAL1 RFIN_LB ATEST_IO1 Figure 1-2. Pin Diagram TEST_EN 1.3 24 PB2 23 PB1 22 PB0 21 DGND 20 DVCC 19 PC5 18 PC4 17 PC3 Pin No. Pin Name Type Description 1 RFIN_LB Analog LNA input for Low-Band frequency range (< 500MHz) 2 RFIN_HB Analog LNA input for High-Band frequency range (> 500MHz) 3 SPDT_RX Analog Rx switch output (damped signal output) 4 SPDT_ANT Analog Antenna input (RXMode) of the SPDT switch 5, 7 NC - 6 SPDT_RX2 Analog RX switch output 2 (damped signal output) 8 VS_SPDT Analog SPDT supply 3V application supply voltage input 9 TEST_EN – 10 XTAL1 Analog Crystal oscillator pin 1 (input) 11 XTAL2 Analog Crystal oscillator pin 2 (output) 12 AVCC Analog RF front end supply regulator output 13 VS Analog Main supply voltage input 14 PC0 Digital Open in application Test enable, connected to GND in application Main : AVR Port C0 Alternate : PCINT8 / NRESET / DebugWIRE Atmel ATA5781 [Summary DATASHEET] 9286BS–RKE–06/13 5 Table 1-2. Pin Description (Continued) Pin No. Pin Name Type Description 15 PC1 Digital 16 PC2 Digital 17 PC3 Digital 18 PC4 Digital 19 PC5 Digital 20 DVCC – Digital supply voltage regulator output 21 DGND – Digital ground 22 PB0 Digital 23 PB1 Digital 24 PB2 Digital 25 PB3 Digital Main : AVR Port C1 Alternate : NPWRON1 / PCINT9 / EXT_CLK Main : AVR Port C2 Alternate : NPWRON2 / PCINT10 / TRPA Main : AVR Port C3 Alternate : NPWRON3 / PCINT11 / TMDO / TxD Main : AVR Port C4 Alternate : NPWRON4 / PCINT12 / INT0 / RxD Main : AVR Port C5 Alternate : NPWRON5 / PCINT13 / TRPB / TMDO_CLK Main : AVR Port B0 Alternate : PCINT0 / CLK_OUT Main : AVR Port B1 Alternate : PCINT1 / SCK Main : AVR Port B2 Alternate : PCINT2 / MOSI (SPI Master Out Slave In) Main : AVR Port B3 Alternate : PCINT3 / MISO (SPI Master In Slave Out) Main : AVR Port B4 26 PB4 Digital 27 PB5 Digital 28 PB6 Digital 29 PB7 Digital 30 AGND – Analog ground 31 ATEST_IO2 – RF front end test I/O 2 connected to GND in application 32 ATEST_IO1 – RF front end test I/O 1 connected to GND in application GND – Ground/backplane on exposed die pad Alternate : PWRON / PCINT4 / LED1 (strong high side driver) Main : AVR Port B5 Alternate : PCINT5 / INT1 / NSS Main : AVR Port B6 Alternate : PCINT6 / EVENT (firmware controlled external microcontroller event flag) Main : AVR Port B7 Alternate : NPWRON6/ PCINT7/ RX_ACTIVE (strong high side driver) / LED0 (strong low side driver) Atmel ATA5781 [Summary DATASHEET] 9286BS–RKE–06/13 6 1.4 Typical Applications The receiver is designed to be used in the following application areas: ● Remote keyless entry system (RKE) ● ● ● ● ● ● Tire pressure monitoring system (TPM, TPMS) Remote start system (RS) Remote control systems, e.g., garage door openers Smart RF applications Telemetering systems Typical 5V Application Circuit with External Microcontroller Figure 1-3. Typical 5V Application Circuit with External Microcontroller IRQ NSS VS RFIN_LB 26 MISO 25 PB3 27 PB4 28 PB5 ATEST ATEST _IO1 _IO2 29 PB6 30 PB7 1 31 AGND 32 24 PB2 23 2 PB1 RFIN_HB 22 3 PB0 SPDT_RX Atmel ATA5781 ATA5782 ATA5783 4 SPDT_ANT SAW 5 NC 6 SPDT_RX2 9 10 11 12 20 DVCC 13 14 CLK_IN PC5 19 PC4 18 PC3 17 15 Microcontroller PC2 PC1 PC0 VS AVCC TEST _EN XTAL2 VS_SPDT SCK DGND NC 8 MOSI 21 7 XTAL1 1.4.1 Passive entry go system (PEG) 16 VS = 5V VDD Figure 1-3 shows a typical vehicle side application circuit with an external host microcontroller running from a 5V voltage regulator. The pin PB4 (PWRON) is directly connected to VS and the Atmel ATA5781/2/3 enters the IDLEMode after power-on. In this configuration the Atmel ATA5781/2/3 can work autonomously and the µC stays powered down to keep current consumption low while remaining sensitive to RF telegrams. To achieve a low current in IDLEMode the Atmel ATA5781/2/3 can be configured in the EEPROM to work with the RC oscillator. The Atmel ATA5781/2/3 can also be configured for autonomous multi-channel and multi-application PollingMode. The external µC is notified by an event on pin 28 (EVENT) if an appropriate RF message is received. Until this event, the Atmel ATA5781/2/3 periodically switches to RXMode, checks the different services and channels configured in the EEPROM, and returns to power-down while the external host microcontroller is still in deep sleep mode to keep average current low. Once a valid RF message is detected, it can be buffered inside of the Atmel ATA5781/2/3 to enable a µC wake-up and retrieval of buffered data. RF_IN is matched to SPDT_RX by absorbing the parasitics of the SPDT switch into the matching network, hence the SPDT_ANT is a 50 RX port. Atmel ATA5781 [Summary DATASHEET] 9286BS–RKE–06/13 7 The impedance of the SAW filter is transformed with LC matching circuits to the SPDT_ANT port and also to the antenna. An external crystal, together with the fractional-N PLL within the Atmel® ATA5781/2/3 is used to fix the RX frequency. Accurate 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. Atmel ATA5781 [Summary DATASHEET] 9286BS–RKE–06/13 8 Figure 2-1. Service-based Concept Overview EEPROM SRAM EEPROM Polling Configuration eepPollLoopConf System Initialization SRAM Polling Configuration pollConfig Service 0 eepServices  Channel 0 Channel 1 Service 3 sramServices  Channel 2 Channel 0 Service 1 eepServices  Channel 0 Channel 1 Channel 1 Channel 2 SPI Service 4 sramServices  Channel 2 Channel 0 Service 2 eepServices  Channel 0 Channel 1 Channel 1 Channel 2 RSSI Threshold Configuration for Each Channel rssiThreshold  Channel 2 Service S currentService Channel Atmel ATA5781/2/3 Hardware 2.1.2 Supported Telegrams The Atmel® ATA5781/2/3 supports the reception of a wide variety of telegrams and protocols. Generally no special structure is required from a telegram to be received by the Atmel ATA5781/2/3. However, designated hardware and software features are built in for the blocks that are depicted in Figure 2-2. Using this structure or parts of it can increase the sensitivity and robustness of the broadcast. Figure 2-2. Telegram Structure Desync Preamble Data Payload Checksum Stop Sequence Desync: The de-synchronization is usually a coding violation with a length of several symbols that should provoke a defined restart of the receiver. The use of a de-synchronization leads to more deterministic receiver behavior, reducing the required preamble length. This can be favorable in timing-critical and energy-critical applications. Preamble: The preamble is a pattern that is sent before the actual data payload to synchronize the receiver and provide the starting point of the payload. A very regular pattern (e.g., 1-0-1-0...) is recommended for synchronization (“wake-up pattern, WUP”, sometimes also called “pre-burst”) while a unique, well-defined pattern of up to 32 symbols is required to mark the start of the data payload (“start frame identifier, SFID” or “start bit”). In polling scenarios the WUP can be tens or hundreds of ms long. Atmel ATA5781 [Summary DATASHEET] 9286BS–RKE–06/13 9 Data Payload: The data payload contains the actual information content of the telegram. It can be NRZ or Manchester-coded. The length of the payload is application dependent, typically 1..64 bytes. Checksum: A checksum can be calculated across the data payload to verify that the data have been received correctly. A typical example is an 8-bit CRC checksum. Data bits at the beginning of the payload can be excluded from the CRC calculation. Stop Sequence: The stop sequence is a short data pattern (typically 2 to 6 symbols) to mark the end of the telegram. A coding violation can be used to prevent additional (non-deterministic) data from being received. 2.2 Operating Modes Overview This section gives an overview of the operating modes supported by the Atmel® ATA5781/2/3 as shown in Figure 2-3. Figure 2-3. Operating Modes Overview OFFMode Power-on Invalid wake-up WDR EXTR Init fails System Initialization pureRXMode TCMode Init done System Error Loop IDLEMode PollingMode RXMode After connecting the supply voltage to the VS pin, the Atmel ATA5781/2/3 always starts in OFFMode. All internal circuits are disconnected from the power supply. Therefore, no SPI communication is supported. The Atmel ATA5781/2/3 can be woken up by activating the PWRON pin or one of the NPWRONx pins. This triggers the power-on sequence. After the system initialization the Atmel ATA5781/2/3 reaches the IDLEMode. The IDLEMode is the basic system mode supporting SPI communication and transitions to all other operating modes. There are two options of the IDLEMode requiring configuration in the EEPROM settings: ● IDLEMode(RC) with low power consumption using the fast RC (FRC) oscillator for processing ● IDLEMode(XTO) with active crystal oscillator for high accuracy clock output or timing measurements The receive mode (RXMode) provides data reception on the selected service/channel configuration. The precondition for data reception is a valid preamble. The receiver continuously scans for a valid telegram and receives the data if all pre-configured checks are successful. The RXMode is usually enabled by the SPI command “Set System Mode”, or directly after power-on, when selected in the EEPROM setting. The pure receive mode (pureRXMode) is a unique receive mode only available as transparent mode. There is no precondition for data reception necessary. It must be enabled in the EEPROM settings and is activated by a special use of pin 18. In PollingMode the receiver is activated for a short period of time to check for a valid telegram on the selected service/channel configurations. The receiver is deactivated if no valid telegram is found and a sleep period with very low power consumption elapses. This process is repeated periodically in accordance with the polling configuration. Atmel ATA5781 [Summary DATASHEET] 9286BS–RKE–06/13 10 The initial settings are stored in the EEPROM and copied during firmware initialization to the SRAM. This allows modification of the PollingMode timing and service/channel configuration during IDLEMode. The tune and check mode (TCMode) offers calibration and self-checking functionality for the VCO and FRC oscillators as well as for temperature measurement, and polling cycle accuracy. This mode is activated via the SPI command “Calibrate and Check”. When selected in the EEPROM settings, tune and check tasks are also used during system initialization after poweron. Furthermore, they can also be activated periodically during PollingMode. Table 2-1 shows the relations between the operating modes and their corresponding power supplies, clock sources, and sleep mode settings. Table 2-1. Operating Modes versus Power Supplies and Oscillators Operation Mode AVR Sleep Mode DVCC AVCC XTO SRC FRC OFFMode - off off off off off IDLEMode(RC) Active mode Power-down(1) off off off off on on on off IDLEMode(XTO) Active mode Power-down(1) on on on on on on off off RXMode Active mode on on on off on PollingMode(RC) - Active period - Sleep period Active mode Power-down(1) on off on off on on on off PollingMode(XTO) - Active period - Sleep period Active mode Power-down(1) on on on on on on off off Notes: 1. During IDLEMode(RC) and IDLEMode(XTO) the AVR microcontroller enters sleep mode to reduce current consumption. The sleep mode of the microcontroller section can be defined in the EEPROM. The power-down mode is recommended for keeping current consumption low. Atmel ATA5781 [Summary DATASHEET] 9286BS–RKE–06/13 11 3. Hardware Description 3.1 Overview The Atmel® ATA5781/2/3 consists of an analog front end, digital signal processing blocks (DSP), an 8-bit AVR sub-system and various supply modules such as oscillators and power regulators. A hardware block diagram of the Atmel ATA5781/2/3 is shown in Figure 3-1. Figure 3-1. Block Diagram AVCC Sequencer State Machine RF Front End Front-end Registers RFIN_LB LNA, Mixer IF AMP SRC, FRC Oscillators Watchdog Timer VS DVCC Supplies and Reset Voltage Monitor Clock Management Debug Wire AVR SubSystem 16 Bit Sync Timer A Rx DSP RFIN_HB D Temp (ϑ) SPDT_RX SPDT SPDT_ANT Damping Support FIFO 8 Bit Async Timers 2x AVR CPU Data FIFO NVM Controller 16 Bit Async Timers 2x VS_SPDT SPDT_RX2 IRQ Fractional N-PLL ROM 24kB CRC Frequency Synthesizer Flash 20kB(1) EEPROM 1152B SRAM 1kByte DATA BUS XTO XTAL1 XTAL2 Port B (8) SPI PB[7:0] Port C (6) PC[5:0] (1) 20kByte Flash for Atmel ATA5782, 20kByte user ROM for Atmel ATA5783, no user memory for Atmel ATA5781 Together with the fractional-N PLL, the crystal oscillator (XTO) generates the local oscillator (LO) signal for the mixer in RXMode. The RF signal comes either from the Low-Band input (RFIN_LB) or from the High-Band input (RFIN_HB) and is amplified by the low-noise amplifier (LNA) and down-converted by the mixer to the intermediate frequency (IF) using the LO signal. A 10dB IF amplifier with low-pass filter characteristic is used to achieve enhanced system sensitivity without affecting blocking performance. After the mixer, the IF signal is sampled using a high-resolution analog-to-digital converter (ADC). Within the Rx digital signal processing (Rx DSP) the received signal from the ADC is filtered by a digital channel filter and demodulated. Two data receive paths, path A and path B, are included in the Rx DSP after the digital channel filter. In addition, the receive path can be configured to provide the digital output of an internal temperature sensor (Temp()). Atmel ATA5781 [Summary DATASHEET] 9286BS–RKE–06/13 12 With the single pole double throw (SPDT) switch the RF signal from the antenna is switched to RFIN in RXMode. The system is controlled by an AVR CPU with 24KB firmware ROM and 20KB user Flash for the Atmel® ATA5781, or with 20KB user ROM for the Atmel ATA5782. 1024-byte EEPROM, 1024-byte SRAM, and other peripherals are supporting the receiver handling. Two GPIO ports, PB[7:0] and PC[5:0], are available for external digital connections, for example, as an alternate function the SPI interface is connected to port B. The Atmel ATA5781/2/3 is controlled by the EEPROM configuration and SPI commands and the functional behavior is mainly determined by firmware in the ROM. Much of the configuration can be modified by the EEPROM settings. The firmware running on the AVR gives access to the hardware functionality of the Atmel ATA5781/2/3. Extensions to this firmware can be added in the 20KB of Flash memory for the Atmel ATA5781. The Rx DSP registers are addressed directly and accessible from the AVR. A set of sequencer state machines is included to perform Rx path operations (such as enable, disable, receive) which require a defined timing parallel to the AVR program execution. The power management contains low-dropout (LDO) regulators and reset circuits for the supply voltages VS, AVCC, and DVCC of the Atmel ATA5781/2/3. In OFFMode all the supply voltages AVCC and DVCC are switched off to achieve very low current consumption. The Atmel ATA5781/2/3 can be powered up by activating the PWRON pin or one of the NPWRON[6:1] pins because they are still active in OFFMode. The AVCC domain can be switched on and off independently from DVCC. The Atmel ATA5781/2/3 includes two idle modes. In IDLEMode(RC) only the DVCC voltage regulator, the FRC and SRC oscillators are active and the AVR uses a power-down mode to achieve low current consumption. The same power-down mode can be used during the inactive phases of the PollingMode. In IDLEMode(XTO) the AVCC voltage domain as well as the XTO are additionally activated. An integrated watchdog timer is available to restart the Atmel ATA5781/2/3 when it is not served within the configured time-out period. 3.2 Receive Path 3.2.1 Overview The receive path consists of a low-noise amplifier (LNA), mixer, IF amplifier, analog-to-digital converter (ADC), and an Rx digital signal processor (Rx DSP). The fractional-N PLL and the XTO deliver the local oscillator frequency in RXMode. The receive path is controlled by the RF front-end registers. Two separate LNA inputs, one for Low-Band and one for High-Band, are provided to obtain optimum performance matching for each frequency range and to allow multi-band applications. A radio frequency (RF) level detector at the LNA output and a switchable damping included into the single-pole double-trough (SPDT) switch is used in the presence of large blockers to achieve enhanced system blocking performance. The mixer converts the received RF signal to a low intermediate frequency (IF) of about 250kHz. A double-quadrature architecture is used for the mixer to achieve high image rejection. Additionally, the third-order suppression of the local oscillator (LO) harmonics makes receiving without a front-end SAW filter less critical, such as in a car key fob application. An IF amplifier provides additional gain and improves the receiver sensitivity by 2-3dB. Because of built-in filter function, the inband compression is degraded by 10dB, while the out-of-band compression remains unchanged. The ADC converts the IF signal into the digital domain. Due to the high effective resolution of the ADC, the channel filter and received signal strength indicator (RSSI) can be realized in the digital signal domain. Therefore, no analog gain control (AGC) potentially leading to critical timing issues or analog filtering is required in front of the ADC. This leads to a receiver front end with excellent blocking performance up to the 1dB compression point of the LNA and mixer, and a steep digital channel filter can be used. The Rx DSP performs the channel filtering and converts the digital output signal of the ADC to the baseband for demodulation. Due to the digital realization of these functions the Rx DSP can be adapted to the needs of many different applications. Channel bandwidth, data rate, modulation type, wake-up criteria, signal checks, clock recovery, and many other properties are configurable. The RSSI value is realized completely in the digital signal domain, enabling very high relative and absolute accuracy that is only deteriorated by the gain errors of the LNA, mixer, and ADC. Two independent receive paths A and B are integrated in the Rx DSP after the channel filter and allow the use of different data rates, modulation types, and protocols without the need to power up the receive path more than once to decide which signal should be received. This results in a reduced polling current in several applications. The integration of remote keyless entry (RKE), passive entry and go (PEG) and tire-pressure monitoring systems (TPM) into one module is simplified because completely different protocols can be supported and a low polling current is achieved. It is even possible to configure different receive RF bands for different applications by using the two LNA inputs. For example, a TPM receiver can be realized at 433.92MHz while a PEG system uses the 868MHz ISM band with multi-channel communication. Atmel ATA5781 [Summary DATASHEET] 9286BS–RKE–06/13 13 3.2.2 Rx Digital Signal Processing (Rx DSP) The Rx digital signal processing (DSP) block performs the digital filtering, decoding, checking, and byte-wise buffering of the Rx samples that are derived from the ADC as shown in Figure 3-2. The Rx DSP provides the following outputs: ● Raw demodulated data at the TRPA/B pins ● ● ● Decoded data at the TMDO and TMDO_CLK pins Buffered data bytes toward the data FIFO and ID check block Auxiliary information about the signal such as the received signal strength indication (RSSI) and the frequency offset of the received signal from the selected center frequency (RXFOA/B) Figure 3-2. Rx DSP Overview RXFOA ADC Data Channel Filter Demod & Check TRPA TMDO_A TMDO_CLK_A Frame Sync A Path A Rx Buffer A Data Byte = Data FIFO Frame Sync B Path B Rx Buffer B Data Byte = RSSI RXFOB RSSI Buffer TRPB Support FIFO TMDO_B TMDO_CLK_B ID Check = The channel filter determines the receiver bandwidth. Its output is used for both receiving paths A and B, making it necessary to configure the filter to match both paths. The receiving paths A and B are identical and consist of an ASK/FSK demodulator with attached signal checks, a frame synchronizer which supports pattern-based searches for the telegram start and a 1-byte hardware buffer with integrated CRC checker for the received data. Depending on the signal checks, one path is selected which writes the received data to the data FIFO and optionally to the ID check block. The RSSI values are determined by the demodulator and written via the RSSI buffer to the support FIFO where the latest 16 values are stored for further processing. Atmel ATA5781 [Summary DATASHEET] 9286BS–RKE–06/13 14 3.3 AVR Controller 3.3.1 AVR Controller Sub-System The AVR controller sub-system consists of the AVR CPU core, its program memory, and a data bus with data memory and peripheral blocks attached. The receive path also has its user interfaces connected to the data bus. CPU Core The main function of the CPU core is to ensure correct program execution. For this reason, the CPU core must be able to access memories, perform calculations, control peripherals, and handle interrupts. Figure 3-3. Architectural Overview Data Bus 8-bit ROM Flash Program Memory Program Counter Status and Control 32 x 8 General Purpose Registers Instruction Register Interrupt Unit SPI Unit Instruction Decoder Control Lines Indirect Addressing Watchdog Timer Direct Addressing 3.3.2 ALU Clock Management I/O Module 1 Data SRAM I/O Module n EEPROM PortN In order to maximize performance and parallelism, the AVR uses a Harvard architecture—with separate memories and buses for program and data. Instructions in the program memory are executed with single-level pipelining. While one instruction is being executed, the next instruction is prefetched from the program memory. This concept enables instructions to be executed in every clock cycle. The program memory is in-system reprogrammable Flash memory and ROM. The fast-access register file contains 32 8-bit general purpose working registers with a single clock cycle access time. This allows a single-cycle arithmetic and logic unit (ALU) operation. In a typical ALU operation, two operands are output from the register file, the operation is executed, and the result is stored back in the register file—in one clock cycle. Six of the 32 registers can be used as three 16-bit indirect address register pointers for data space addressing, enabling efficient address calculations. One of these address pointers can also be used as an address pointer for lookup tables in the Flash program memory. Referred to as ‘X,’ ‘Y,’ and ‘Z’ registers, these higher 16-bit function registers are described later in this section. Atmel ATA5781 [Summary DATASHEET] 9286BS–RKE–06/13 15 The ALU supports arithmetic and logic operations between registers or between a constant and a register. Single register operations can also be executed in the ALU. After an arithmetic operation, the status register is updated to reflect information about the result of the operation. The program flow is provided by conditional and unconditional jump and call instructions which are able to directly address the entire address space. Most AVR instructions have a single 16-bit word format. Every program memory address contains a 16or 32-bit instruction. The program memory space is divided in two sections, the boot program section and the application program section. Both sections have dedicated lock bits for write and read/write protection. The store program memory (SPM) instruction that writes into the application Flash memory section must reside in the boot program section. During interrupts and subroutine calls, the return address of the program counter (PC) is stored on the stack. The stack is effectively allocated in the general data SRAM—the stack size is thus only limited by the total SRAM size and the usage of the SRAM. All user programs must initialize the stack pointer (SP) in the reset routine before subroutines or interrupts are executed. The SP is read/write accessible in the I/O space. The data SRAM can easily be accessed through the five different addressing modes supported in the AVR architecture. The memory spaces in the AVR architecture are all linear and regular memory maps. A flexible interrupt module has its control registers in the I/O space with an additional global interrupt enable bit in the status register. All interrupts have a separate interrupt vector in the interrupt vector table. The interrupts have priority in accordance with their interrupt vector position. The lower the interrupt vector address, the higher the priority. The I/O memory space contains 64 addresses for CPU peripheral functions as control registers, SPI, and other I/O functions. The I/O memory can be accessed directly, or as the data space locations following those of the register file, 0x20 - 0x5F. In addition, the circuit has extended I/O space from 0x60 - 0x1FF and SRAM where only the ST/STS/STD and LD/LDS/LDD instructions can be used. Atmel ATA5781 [Summary DATASHEET] 9286BS–RKE–06/13 16 3.4 Power Management The IC has four power domains: 1. VS – Unregulated battery voltage input 2. DVCC – Internally regulated digital supply voltage. Typical value is 1.35V. 3. AVCC – Internally regulated RF front end and XTO supply. Typical value is 1.85V. 4. VS_SPDT – This is used to achieve full PCB and RF application compatibility with Atmel® ATA5831/2/3, in Atmel ATA5781/2/3 this supply is always switched off and connected externally to the battery in 3V applications: The Atmel ATA5781/2/3 can be operated from VS= 1.9V to 3.6V (3V applications) and from VS = 2.4V to 5.5V (5V application). Figure 3-4. Power Supply Management 2.2µF 220nF 22nF AVCC VS DVCC Power Management (common reference, Voltage Monitor) DVCC regulator AVCC regulator Data Bus RFIN_LB RFIN_HB AVR CPU, AVR peripherals, Memories, RxDSP and FRC/SRC SPDT_RX SPDT_ANT RF front end and XTO SPDT_RX2 Port B SPI Port C VS_SPDT (only 3V operation) 68nF PB7 XTAL1 ... Level shifter PB4 XTAL2 VS PC5 ... PC1 ... Atmel ATA5781 [Summary DATASHEET] 9286BS–RKE–06/13 17 4. Ordering Information Extended Type Number Package Remarks ATA5781-PNQW QFN32 5mm x 5mm, 6k tape and reel, PB-free ATA5782-nnn-PNQW QFN32 5mm x 5mm, 6k tape and reel, PB-free, nnn = Customer ROM identifier ATA5783-PNQW QFN32 5mm x 5mm, 6k tape and reel, PB-free Package Information Top View D 32 E 1 PIN 1 ID technical drawings according to DIN specifications Side View Dimensions in mm A3 A1 8 A Standard Singulation process Bottom View D2 9 16 17 COMMON DIMENSIONS E2 8 1 (Unit of Measure = mm) 24 25 32 e Z Z 10:1 L 5. Symbol MIN NOM MAX A 0.8 0.9 1 A1 0.0 0.02 0.05 A3 0.15 0.2 0.25 D 4.9 5 5.1 D2 3.45 3.6 3.75 E 4.9 5 5.1 E2 3.45 3.6 3.75 L 0.3 0.4 0.5 b 0.16 0.23 0.3 e NOTE 0.5 BSC b 09/07/11 TITLE Package Drawing Contact: [email protected] Package: VQFN_5x5_32L Exposed pad 3.6x3.6 GPC DRAWING NO. REV. 6.543-5124.01-4 3 Atmel ATA5781 [Summary DATASHEET] 9286BS–RKE–06/13 18 6. Revision History Please note that the following page numbers referred to in this section refer to the specific revision mentioned, not to this document. Revision No. History 9286BS-RKE-06/13 Features on pages 1 to 2 updated Atmel ATA5781 [Summary DATASHEET] 9286BS–RKE–06/13 19 Atmel Corporation 1600 Technology Drive Atmel Asia Limited Unit 01-5 & 16, 19F Atmel Munich GmbH Business Campus Atmel Japan G.K. 16F Shin-Osaki Kangyo Building San Jose, CA 95110 BEA Tower, Millennium City 5 Parkring 4 1-6-4 Osaki USA 418 Kwun Tong Roa D-85748 Garching b. Munich Shinagawa-ku, Tokyo 141-0032 Tel: (+1) (408) 441-0311 Kwun Tong, Kowloon GERMANY JAPAN Fax: (+1) (408) 487-2600 HONG KONG Tel: (+49) 89-31970-0 Tel: (+81) (3) 6417-0300 www.atmel.com Tel: (+852) 2245-6100 Fax: (+49) 89-3194621 Fax: (+81) (3) 6417-0370 Fax: (+852) 2722-1369 © 2013 Atmel Corporation. All rights reserved. / Rev.: 9286BS–RKE–06/13 Atmel®, Atmel logo and combinations thereof, AVR®, Enabling Unlimited Possibilities®, and others are registered trademarks or trademarks of Atmel Corporation or its subsidiaries. Other terms and product names may be trademarks of others. Disclaimer: The information in this document is provided in connection with Atmel products. No license, express or implied, by estoppel or otherwise, to any intellectual property right is granted by this document or in connection with the sale of Atmel products. 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