9254E-RKE-08/14
Features
●AES-128 crypto transponder in plastic brick package
●Includes coil and capacitor for tuned circuit antenna
●Radio frequency fRF = 125kHz
●Contactless power supply
●Contactless bidirectional data communication interface
●High-performance AES-128 encryption hardware unit
●Atmel® open immobilizer stack
●2K EEPROM for secret key storage, field user data and configuration data
●Error correction code support for NVM
●32-bit unique ID
●Multiple configuration registers
●Modulation/coding: Biphase, Manchester, QPLM
●Configurable baud rate
●–40°C to +85°C operation temperature
●LGA-like brick package
ATA5580
125kHz Transponder with Open Immobilizer Software
Stack and AES-128 Encryption
DATASHEET
ATA5580 [DATASHEET]
9254E–RKE–08/14
2
1. Description
The Atmel® ATA5580 is a smart transponder module with an AES-128 encryption unit, customer EEPROM, a 125kHz LF
front end and an LF ferrite antenna for wireless power supply and communication. All components are built up in a single
pinless transponder package. The IC contains the highly configurable Atmel open immobilizer software stack.
1.1 Module Schematic
The Atmel ATA5580 transponder contains an ultra-low-power transponder IC with an AES-128 engine, an LF Antenna
resonant circuit and a buffer capacitor.
1.2 Functional Description
Atmel ATA5580 is designed for automotive immobilization applications in remote keyless entry (RKE) keys. The Atmel
ATA5580 micro module consists of an ultra-low-power IC with AES-128 encryption engine and immobilizer front end, an LF
ferrite antenna and capacitors for the antenna and as supply buffer.
The small LGA-like package of the Atmel ATA5580 contains all the components required for the transponder application.
Because it is powered by a 125kHz LF field, the IC requires no battery supply. The communication with the chip is also
implemented via an LF field. A base station can request data via an LF telegram and the transponder responds with data
from its memory or with cipher data via a damping modulation from the LF field. The transponder function is defined by a
special Atmel immobilizer stack.
Figure 1-1. Block Diagram
C2
LF Antenna
ATA5580 IC
ATA5580
L1
3
ATA5580 [DATASHEET]
9254E–RKE–08/14
2. Atmel Open Immobilizer Protocol Description
2.1 Overview
2.1.1 Protocol Flex ib ility
The Atmel® immobilizer protocol has been designed as a configurable software stack.
For example, security levels, turn-around authentication time and authentication schemes are all configurable at run time
while covering a wide range of car manufacturer requirements.
Additionally, Atmel defined three default configurations respectively targeting fast, standard, and high security for which
analysis of bit security strength vs. turn-around time was carried out. Obviously, flexibility for tuning the protocol stack to
meet specific constraints is still a feature.
2.1.2 Open Software Stack
Rather than developing its own proprietary cryptographic functions, Atmel selected and implemented the 128-bit AES-128
global benchmark standard as its data encryption and decryption source. This open source standard is freely available to the
public for use and scrutiny. Because of this it continues to be favored by industry experts over private and proprietary crypto
algorithms.
In addition to selecting an open source and public AES-128 crypto function, the firmware includes user-configurable options
that enable the engineer to “build” an authentication protocol that meets user requirements. The complete documentation of
the protocol configuration options are made publicly available. The encryption and configuration of the authentication
protocol are open source and freely available to customers free of charge.
2.1.3 Production-Ready Software Implementation
Besides defining an open immobilizer protocol stack, Atmel chose to implement it in all car access devices with an
embedded LF front end. This implementation complies with automotive grade development standards (CMMI - Automotive
Spice) and is production-ready.
2.2 System Overview
As a sub-system of the general car access system, the immobilizer is not used for accessing the car but instead to allow the
driver to start the engine. Figure 2-1 shows system partitioning.
Figure 2-1. System Overview
Key Fob Containing
the Microcontroller-
based Transponder
125kHz
Downlink LIN/K Line/SPI/UART-
based Communication
Interface
TP
Key Car
BS
Uplink
Atmel Immobilizer
System Software
Base Station
Containing the
Microcontroller-
based Transceiver
BCM
Body Control Module
Containing the
Main Controller
ATA5580 [DATASHEET]
9254E–RKE–08/14
4
2.3 Device Support
The firmware implementation developed by Atmel® uses specific hardware blocks that are found in our vehicle access
product line. The transponder features are optimized to function seamlessly with the following devices:
●Atmel ATA5580: stand-alone transponder
●Atmel ATA5790: passive entry/go microcontroller with 3D LF receiver and transponder interface
●Atmel ATA5794: RKE microcontroller with transponder interface
●Atmel ATA5795: RKE microcontroller with transponder interface and Frac-N RF transmitter.
The Atmel base-station device ATA5272 includes a matched firmware library for implementing the entire system.
The transponder’s hardware and software layers have been specifically designed to be compatible with any FDX base
station available on the market by implementing the protocol described in this document on the host microcontroller.
2.4 Firmware Features
The purpose of this section is to provide an overview of the complete immobilizer features included with the Atmel firmware
library. It also describes the information flow between the car-side base station and the key-side transponder. It includes
definitions and requirements in terms of physical layer, protocol layer and encryption.
2.5 Memory Partitioning
Except for the Atmel ATA5580, there are two types of memory on the Atmel devices used by both the immobilizer and the
application. These memories need to be partitioned and some guidelines established to ensure reliable operation. Program
code stored in flash memory is typically used as read-only memory once initial programming has occurred. Non-volatile
memory that supports multiple read/write access is provided through EEPROM memory structures.
2.5.1 Flash Memory
The immobilizer firmware developed by Atmel is stored in the bootloader section of the flash memory. It is shipped from
Atmel with the bootloader section protected against overwriting through the use of fuse settings. This allows the application
space to be programmed without corrupting the immobilizer firmware.
Each Atmel device provides differing amounts of flash memory. The bootloader space is consistent across devices at
2Kbytes. In the case of the Atmel ATA5580 all of the flash memory (8K) is available for the immobilizer stack. Figure 2-2 on
page 5 shows how the flash memory is partitioned for various memory sizes.
5
ATA5580 [DATASHEET]
9254E–RKE–08/14
Figure 2-2. The Flash Memory Partition
2.5.2 Non-Volatile Me mory
Non-volatile memory used for data storage is implemented in EEPROM structures. It is subdivided into two pages.
Page one provides read and write access for storage of application and immobilizer data. This includes four special access
protection (AP0 - AP3) areas. The protection takes the form of requiring an intentional setting of the second register before
programming is possible. The AP0 location has been selected for exclusive use by the Atmel® immobilizer firmware. The
application code should be audited to ensure that this memory is not used and also to prevent corruption.
Figure 2-3 on page 6 shows the use of EEPROM page 1.
Address
0x0000 0
0x1BFE 7166
0x1BFF 7167
0x1FFF 8191
0x0BFE 3070
0x0BFF 3071
0x0FFF 4095
015Address
Flash 8kBytes
0x0000 0
015
Application Space
(7166 Words)
Boot Loader
(1024 Words)
Application Space
(3070 Words)
Boot Loader
(1024 Words)
Flash 16kBytes
ATA5580 [DATASHEET]
9254E–RKE–08/14
6
Figure 2-3. EEPROM Page 1
Page 2 is locked from overwriting at the end of Atmel® manufacturing. This page contains a comprehensive set of
configuration and identification features. Once these have been set, they are protected from any subsequent changes.
2.5.2.1 Secret Key Storage
Atmel makes provisions for a total of three secret keys that can be used. One of these is the fixed default secret key which
resides in the locked page 2 of EEPROM and is intended for use during a secure key transfer process to establish the other
two secret keys.
The other two secret keys are intended for use during normal operation. These are stored in the AP0 section of EEPROM
when the supplied LF interface is used to pair the transponder to the vehicle. To ensure integrity, the LF interface for
transferring secret keys also stores each of these two secret keys with two copies. When the secret key is accessed for the
authentication process, all three copies are read out and checked against each other for errors. Any corruption of a single
copy can be automatically corrected. Figure 2-4 on page 7 shows the mapping of the AP0 section located in page 1 of
EEPROM.
The size of the secret key is 16 bytes.
The secret keys for the immobilizer and the application must be stored based on the configuration stored in page 2.
Both secret key1 and secret key2 must be stored with two copies in their respective locations.
Figure 2-4 on page 7 represents the allocation of the secret key in the EEPROM memory.
Address
0x0000 0
0x077F 1919
0x0780 1920
0x06FF 1791
0x0700 1792
0x067F 1663 AP3
AP2
AP1
AP0
0x0680 1664
0x05FF 1535
0x0600 1536
0x07FF 2047
07
Application Space
(1920 Bytes)
Key
Space
(128
Bytes)
EEPROM 2kBytes
7
ATA5580 [DATASHEET]
9254E–RKE–08/14
Figure 2-4. The AP0 Memory Map
The unassigned locations of AP0 are reserved for the immobilizer firmware for general variable storage.
2.5.2.2 Configuration Memory Options
The Atmel® firmware includes highly configurable immobilizer features allowing the system design to be optimized. All
configuration options must be selected during design testing and validation and are placed and locked in page 2 of
EEPROM.
Data Check Disable
EEPROM address 0x0815 bit 0 allows the CRC data to be disabled for both the request frame and the response frame.
Data check disable (DCD): 0 = CRC enabled, 1 = CRC disabled
This configuration bit is checked when sending or receiving all commands.
Authentication Format
EEPROM address 0x0815 bit 2 allows the type of authentication protocol to be selected.
Crypto mode (CM): 0 = Unilateral, 1 = Bilateral
This configuration bit is checked when the start authentication and memory access commands are executed. Details of this
interaction are provided in the LF command set section.
Challenge and Response Length
These two configuration registers deal with the number of bits transferred during authentication. The length of the challenge
that the transponder expects is stored in EEPROM address 0x0819. In response the transponder returns an encrypted value
with a length determined by the setting in address 0x081A. The “Start Authentication” command must have knowledge of
these length settings used in the authentication protocol.
Data 1Secret Key
20780 - 078F
0790 - 079F
07A0 - 07AF
07B0 - 07BF
07C0 - 07CF
07D0 - 07DF
07E0 - 07EF
07F0 - 07FF
2 (Copy 1)
2 (Copy 2)
1
1 (Copy 1)
1 (Copy 2)
128 Bytes of Secret Key Memory
128 Bit
Data 2 Data 3 Data 4 Data 5 Data 6 Data 7 Data 8 Data 9 Data 10 Data 11 Data 12 Data 13 Data 14 Data 15 Data 16 Physical Address
AP0 128 Bytes
Byte Address Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Remarks
815 TDH SKT KS DLP1 DLP0 CM MOD DCD Configuration
Byte Address Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Remarks
815 TDH SKT KS DLP1 DLP0 CM MOD DCD Configuration
Byte Address Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Remarks
819 CH7 CH6 CH5 CH4 CH3 CH2 CH1 CH0 Challenge length
81A RS7 RS6 RS5 RS4 RS3 RS2 RS1 RS0 Response length
ATA5580 [DATASHEET]
9254E–RKE–08/14
8
Uplink Coding and Data Rate
EEPROM address 0x0815 bit 1 allows the uplink coding type to be selected.
Uplink modulation (MOD): 0 = Manchester, 1 = Biphase
The baud rate setting (0x0817) sets the threshold for the Manchester/Biphase encoder. This works in combination with the
T2 prescaler (0x0818) to provide a very accurate and flexible transmission of data from the transponder to the vehicle. A
typical value is recommended as 0x07 and 0x00 respectively to provide approximately 3.906kb/s.
Downlink Coding and Data Rate
EEPROM address 0x0815 bits 3 and 4 allows the downlink coding type to be selected.
Downlink protocol (DLP1:0): 00 = BPLM, 01 = QPLM (one of four codings), 10 = DPS
The PLM threshold (0x0816) sets the threshold used to decode BPLM data from the vehicle. The value in this register (PLM0
- PLM7) is used to determine if the number of field clock cycles received represents a logical zero or one. For example, a
typical BPLM configuration uses 16 field clocks to represent a zero and 32 field clocks to represent a one. The threshold
setting can then be set to 24 to achieve accurate decoding.
In QPLM mode the PLM threshold becomes the reference value that is used to determine the four possible state values.
Secret Key Selection and Transfer
EEPROM address 0x0815 bits 5 and 6 configure the handling of secret keys in the system.
Key select (KS): 0 = Secret key one, 1 = Secret key two
Secure key transfer (SKT): 0 = OFF, 1 = ON
The secret key selected in this option determines which key from the AP0 section of EEPROM is used during the “Start
Authentication” command. In addition, the type of key transfer process used to load the secret keys into AP0 is specified
using this configuration.
Byte Address Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Remarks
815 TDH SKT KS DLP1 DLP0 CM MOD DCD Configuration
816 PLM7 PLM6 PLM5 PLM4 PLM3 PLM2 PLM1 PLM0 PLM threshold
817 BD7 BD6 BD5 BD4 BD3 BD2 BD1 BD0 Baud rate setting
818 T23 T22 T21 T20 T2D1 T2D0 T2 prescaler
Byte Address Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Remarks
815 TDH SKT KS DLP1 DLP0 CM MOD DCD Configuration
816 PLM7 PLM6 PLM5 PLM4 PLM3 PLM2 PLM1 PLM0 PLM threshold
Byte Address Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Remarks
815 TDH SKT KS DLP1 DLP0 CM MOD DCD Configuration
9
ATA5580 [DATASHEET]
9254E–RKE–08/14
Fob Power-Up
EEPROM address 0x0815 bit 7 allows the detection header functionality to be selected.
Detection header (TDH): 0 = OFF, 1 = ON
This configuration determines if the detection header is included as part of the immobilizer initialization routine.
Default Secret Key
A 128-bit default secret key is programmed and locked into EEPROM address locations 0x081B to 0x82A. It is programmed
identically for all devices that are shipped to the customer and includes the customer ID address (0x081B). The remaining 15
bytes of data can be specified by the customer or assigned by Atmel®. This default secret key cannot be read out of
EEPROM by LF field commands. The default secret key is used for the secure key transfer process.
Byte Address Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Remarks
815 TDH SKT KS DLP1 DLP0 CM MOD DCD Configuration
Byte Address Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Remarks
81B CID7 CID6 CID5 CID4 CID3 CID2 CID1 CID0 Customer ID
81C SK119 SK118 SK117 SK116 SK115 SK114 SK113 SK112 Default secret key
81D SK111 SK110 SK109 SK108 SK107 SK106 SK105 SK104
81E SK103 SK102 SK101 SK100 SK99 SK98 SK97 SK96
81F SK95 SK94 SK93 SK92 SK91 SK90 SK89 SK88
820 SK87 SK86 SK85 SK84 SK83 SK82 SK81 SK80
821 SK79 SK78 SK77 SK76 SK75 SK74 SK73 SK72
822 SK71 SK70 SK69 SK68 SK67 SK66 SK65 SK64
823 SK63 SK62 SK61 SK60 SK59 SK58 SK57 SK56
824 SK55 SK54 SK53 SK52 SK51 SK50 SK49 SK48
825 SK47 SK46 SK45 SK44 SK43 SK42 SK41 SK40
826 SK39 SK38 SK37 SK36 SK35 SK34 SK33 SK32
827 SK31 SK30 SK29 SK28 SK27 SK26 SK25 SK24
828 SK23 SK22 SK21 SK20 SK19 SK18 SK17 SK16
829 SK15 SK14 SK13 SK12 SK11 SK10 SK9 SK8
82A SK7 SK6 SK5 SK4 SK3 SK2 SK1 SK0
ATA5580 [DATASHEET]
9254E–RKE–08/14
10
2.5.2.3 Fixed Identification
Fixed identification contains data that has been programmed and locked by Atmel®. This data is provided for use in the
immobilizer application as well as part of supply chain management.
Unique ID
The ID or serial number consists of 32 bits of non-sequential, unique values. Each transponder is assigned this value at the
end of the manufacturing process. The value is stored at EEPROM address locations 0x0800 to 0x0803. This value can be
accessed very efficiently using the “Read UID” command.
The customer ID stored at address 0x0804 may optionally be added to the unique ID.
Atmel Traceability
Atmel traceability entails information that can be used to determine where and how this device has been processed. The
following information completely identifies this device in the Atmel process chain:
Address - Value
0x0808 - Device type
0x0809 to 0x080B - Lot number
0x080C - Wafer number
0x080D to 0x080E - Die number
Software Revision
The software revision is contained in EEPROM address 0x080F and provides information about the current version loaded
into flash memory.
Byte Address Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Remarks
800 ID31 ID30 ID29 ID28 ID27 ID26 ID25 ID24 Unique ID / Serial #
801 ID23 ID22 ID21 ID20 ID19 ID18 ID17 ID16
802 ID15 ID14 ID13 ID12 ID11 ID10 ID9 ID8
803 ID7 ID6 ID5 ID4 ID3 ID2 ID1 ID0
804 CID7 CID6 CID5 CID4 CID3 CID2 CID1 CID0 Customer ID
Byte Address Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Remarks
808 DEV7 DEV6 DEV5 DEV4 DEV3 DEV2 DEV1 DEV0 Device type
809 LOT23 LOT22 LOT21 LOT20 LOT19 LOT18 LOT17 LOT16 LOT number
80A LOT15 LOT14 LOT13 LOT12 LOT11 LOT10 LOT9 LOT8
80B LOT7 LOT6 LOT5 LOT4 LOT3 LOT2 LOT1 LOT0
80C WAF7 WAF6 WAF5 WAF4 WAF3 WAF2 WAF1 WAF0 Wafer number
80D DIE15 DIE14 DIE13 DIE12 DIE11 DIE10 DIE9 DIE8 Die number
80E DIE7 DIE6 DIE5 DIE4 DIE3 DIE2 DIE1 DIE0
Byte Address Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Remarks
80F SW7 SW6 SW5 SW4 SW3 SW2 SW1 SW0 SW revision
11
ATA5580 [DATASHEET]
9254E–RKE–08/14
2.6 Device Initialization
This section describes how the transponder device handles the initial power-up sequence. The outcome or determination
from the initialization sequence depends on various conditional paths. These are described in the following sections. The
system can guarantee that the immobilizer functionality is given the highest priority and can operate independently from the
application code by means of this initialization sequence.
2.6.1 Power-up Scenarios
Power-up occurs whenever there is a reset event. This can be power-on-reset (POR), external reset, watchdog reset,
brown-out reset, and transponder reset. All registers, ports, and SRAM are set to initial conditions during the reset. The
program counter is always set to the reset vector located in the bootloader section. This ensures the priority of the
immobilizer over all other functions. After a fixed delay, a code is executed to check the conditions described as follows.
2.6.2 LF Field De te ct io n
The very first item checked after the reset delay is the determination of the presence of an LF field. If the LF field is present,
then the immobilizer function is used and the other conditional checks can be skipped and the immobilizer function executed.
If the LF field is NOT present, the initialization routine will eventually exit to the application code section after the next step.
Transponder initialization will not occur.
2.6.3 Enhanced Mode Detection
This command does not apply to the Atmel® ATA5580 and is ignored.
2.6.4 Transponder Initialization
Once all conditions have been met for entering transponder mode, the following items are configured to prepare for
communication:
●The presence of an LF field has to be acknowledged in order to enable operation of the transponder
●System clocks are reconfigured
●System resources are configured for the lowest power consumption possible
●The interrupt vector table is mapped into bootloader space
●The watchdog timer is configured and activated
●System resources for uplink and downlink communication processing are initialized
2.6.5 Reliable Communication Channel Indication
Once the device has been initialized for transponder mode, an indication of this readiness can be conveyed to the base
station if selected during device configuration. This is achieved through the transmission of a detection header that ensures
with high probability that the communication channel is open and reliable. Both the uplink and downlink paths are verified by
this in the manner described here.
For the downlink to be successful, the transponder must receive enough power to operate. Once this condition is satisfied for
a long enough time to charge a buffer capacitor, the transponder can survive field gaps needed to transfer data. The fact that
the initialization routine was successfully executed up to this point means it has been achieved.
For the uplink to be successful, the transponder must modulate the carrier field with sufficient coupling and modulation depth
for the base station to be able to recover the data from the carrier. By sending a modulated signal as defined by the detection
header, the base station can make a determination that the uplink path is open once the header is visible on the
demodulated output.
2.7 LF Physical Layer
All communication between the base station and the transponder occurs using the LF field as the signal carrier. The LF
communication link is established when the transponder transmits the LF channel detection header consisting of a
Manchester coded sequence of “1010…” as a 125kHz signal which continues until the base station interrupts the signal
during a damped phase with a gap.
The physical layer (uplin k and downlink) is compatible with all sta nd ard FDX bas e station s availab le o n the ma rket.
ATA5580 [DATASHEET]
9254E–RKE–08/14
12
The LF channel consists of data communication sessions comprised of a downlink (base station to transponder) and an
uplink (transponder to base station) data transfer.
Figure 2-5 shows a transponder start-up sequence after which the LF communication channel is established.
Figure 2-5. LF Physical Layer
2.7.1 Downlink
A downlink channel is established when the data is being transmitted from the base station to the transponder. The downlink
communication uses amplitude modulation (AM) in the form of ON/OFF keying (OOK). To encode data pulse length coding
is used. The pulses and LF bursts are separated by gaps. Data can be encoded in the following ways:
Binary pulse length modulation (BPLM): single pulse length is decoded to a single binary logic state (1-bit value).
Quad pulse length modulation (QPLM): also known as 1-of-4 encoding. In this case a single pulse length is decoded into
dual binary logic state (2-bit value).
Damped phase synchronized modulation (DPS): While the transponder modulates the field with a sequential pattern of
Manchester coded “0”, the base station stops or continues sending the field during the second half of the bit (damped phase)
to transmit “1s” or “0s”.
Figure 2-6. Downlink
TCHARGE
TTpinit
TSTUP
Start-up
LF-field Detection C_buffer Charge
Transponder
Detection Header
Transponder
Ready for
Communication
Damped Mode
“0“ = 16 Periods of
125kHz Signal
“1“ = 32 Periods of
125kHz Signal
Gap = Bit Separator
TBit0 TGap TBit1
Start Gap Bit Frame
Start Gap Bit Frame Bit Frame Bit Frame Bit Frame
Bit Frame
Binary Pulse Length Modulation (BPLM)
Quad Pulse Length Modulation (QPLM)
'0'
'b00' '0b01' '0b10' '0b11'
'1'
Gap as Bit Separator
TSG
13
ATA5580 [DATASHEET]
9254E–RKE–08/14
2.7.2 Uplink
An uplink channel is established when the data is being transmitted from the transponder to the base station. The uplink
communication utilizes AM by modulating the induced voltage on the transponder coil down to 50% of its un-damped
amplitude (50% modulation depth). Binary data is either biphase or Manchester encoded.
Figure 2-7. Uplink (3.9 06 K B /s )
2.8 LF Communication
The protocol developed by Atmel® relies on two frame structures for the bidirectional communication. The downlink path
from the base station to the transponder consists of a request frame. The uplink path uses the response frame defined
below.
Communication sessions consist of a base station request, a 2ms delay, and a transponder response. All communication
follows this process and creates functionality by executing a series of communication sessions. The base station request
contains the means to utilize the command set provided by the Atmel firmware. All commands have a defined response that
is returned from the transponder. The command set indicates that the response only occurs if communication is successful.
Any errors that occur cause the transponder to signal the base station in a unique manner by sending a fixed 1kHz
waveform. This allows very rapid detection of a problem. The exact cause of the error is stored and can be accessed by a
dedicated command.
2.8.1 Request Frame Definition
All transactions are initiated by the base station sending the following:
Command field = 4-bit command + 4-bit command CRC
Data field = variable bit length payload (optional based on command)
CRC field = payload CRC8 (optional based on presence of payload data)
LF Data Bit
Undamped Mode
Undamped Mode
Manchester-
coded Bit
Manchester-
coded Bit “0“
32 * 125kHz Signals
Manchester-
coded Bit “1“
TBit TBit
Command Field Data Field CRC Field
4 bits CRC4 Variable SW revision
ATA5580 [DATASHEET]
9254E–RKE–08/14
14
2.8.2 Response Frame Definition
All responses the transponder makes to the base station include sending the following:
Header field = recognizable pattern fixed at 0xFE
Data field = variable bit length payload (optional based on command)
CRC field = payload CRC8 (optional based on presence of payload data)
2.9 LF Command Set
2.9.1 Read UID
The “Read UID” command provides a very concise method for accessing the 32-bit unique serial number stored in the
transponder. The serial number is assigned at the Atmel® fabrication plant and provides a unique identity for use in the
immobilizer system. The request from the base station is streamlined to provide a very rapid response consisting of only the
4-bit command and 4-bit CRC. The response contains the unique identifier. The EEPROM address designated for the
unique identifier location starts from 0x810 and ends with 0x80D (4 bytes).
Figure 2-8. The Read UID Sequence
Command Field Data Field CRC Field
4 bits CRC4 Variable SW revision
Table 2-1. The Read UID (Request Frame)
Field Size Values Description
Command ID 4 + 4 bits 0000b + 0000 CRC Read UID
Data payload N/A
CRC N/A
Table 2-2. The Read UID (Response Frame)
Field Size Values Description
Preamble header 1 byte 0xFE Synchronization
Data payload 4 bytes EEPROM value Serial number (ID0 to ID31)
CRC 1 byte Calculate
0000b
(4 Bits)
0xFE
(1 Byte) 1 Byte
EEPROM Values
ID0 to ID31 (4 Bytes)
Preamble
Header
Data
Payload
CRC
Command ID
From Base Station
Request Frame
Response Frame
From Transponder
CRC
(4 Bits)
tRXDATA_max tTXDATA_max
15
ATA5580 [DATASHEET]
9254E–RKE–08/14
2.9.2 Transponder Error Status
The status byte contains both error information and command execution state information. By directly requesting this byte,
the base station can determine the cause of an error or determine the last command executed. This allows a base station
error to be remedied without complete loss of previously executed functions.
Figure 2-9. The Transponder Error Status Sequence
Table 2-3. The Transponder Error Status (Request Frame)
Field Size Values Description
Command ID 4 + 4 bits 0010b + 0110 CRC Request status byte
Data payload N/A
CRC N/A
Table 2-4. The Transponder Error Status (Response Frame)
Field Size Values Description
Preamble header 1 byte 0xFE Synchronization
Data payload 1 byte Status Status
CRC 1 byte Calculate
0011b
(4 Bits)
0xFE
(1 Byte)
Status
(4+4 Bits) 1 Byte
Preamble
Header
Data
Payload
CRC
Command ID
From Base Station
Request Frame
Response Frame
From Transponder
CRC
(4 Bits)
tRXDATA_max tTXDATA_max
ATA5580 [DATASHEET]
9254E–RKE–08/14
16
2.9.3 Start Authentication
The immobilizer authentication protocol is to be based on challenge-response topology. This can be the unilateral
authentication (UA) method or bilateral authentication (BA).
The “Start Authentication” command causes an authentication protocol to begin. The length of the request payload
(challenge length) is dependent upon the setting stored in the EEPROM page 2 address 0x815 and the response length is
dependent upon the setting stored at the EEPROM page 2 address 0x816.
The type of protocol that is used depends on the configuration stored at the EEPROM page 2 register address 0x811. Bit 2
(CM) defines the crypto model selected (0=UA or 1=BA). The authentication protocol can be selected based on security level
and authentication time requirement. Every protocol implementation utilizes AES-128 block cipher encryption and depending
on security level uses different variable bit length ciphers.
Figure 2-10. The Start Authentication Sequence
Table 2-5. Start Authentication (Request Frame)
Field Size Values Description
Command ID 4 + 4 bits 0001b + 0011 CRC Start authentication
Data payload Varies (104 or 128 bits
recommended) Challenge bits Depends on EEPROM
page 2 setting
CRC 1 byte Calculate
Table 2-6. Start Authentication (Response Frame)
Field Size Values Description
Preamble header 1 byte 0xFE Synchronization
Data payload Varies (56 or 80 bits
recommended) Response bits Depends on EEPROM
page2 setting
CRC 1 byte Calculate
0001b
(4 Bits)
0xFE
(1 Byte) 1 Byte
Challenge Bits
(Depends on
Setting at 0x815)
Response Bits
(Depends on
Setting at 0x816)
Preamble
Header
Data Payload CRC
Command ID Data Payload CRC
1 Byte
From
Base Station
Request
Frame
Response Frame
From Transponder
CRC
(4 Bits)
tRXDATA_max tTXDATA_max
17
ATA5580 [DATASHEET]
9254E–RKE–08/14
2.9.4 Learn Secret Key 1
This command starts the learn secret key1 process for the first secret key. Depending on the configuration setting stored in
EEPROM page 2 at address 0x811(bit 6) it is either open transfer or secure transfer. If the bit (SKT- secure key transfer bit)
is 0, the transfer is open mode and if the bit is 1, the transfer is secure mode. The request frame carries a128-bit secret key
data payload (may be encrypted during secure transfer). The 128-bit key transferred through this command is stored in AP0
key position 1 (0x7C0) along with two copies. The response frame consists of a status byte at the data payload. The status
byte is stored in RAM and updated with each communication session. The status byte consists of the last command received
(MS 4 bits) and an error flag (LS 4 bits). Status byte [7:4]: Four MSBs of the field contain an echo of the command received
in the last request frame. Status byte [3:0]: Four LSBs of the field contain status information in encoded form.
Figure 2-11. The Learn Secret Key1 Sequence
Table 2-7. The Learn Secret Key1 (Request Frame)
Field Size Values Description
Command ID 4 + 4 bits 0111b + 1001 CRC Learn secret key1
Data payload 128 bits AES-128 (possibly
encrypted) secret key
CRC 1 byte Calculate
Table 2-8. Learn Secret Key1 (Response Frame)
Field Size Values Description
Preamble header 1 byte 0xFE Synchronization
Data payload 1 byte Status Status
CRC 1 byte Calculate
0111b
(4 Bits)
0xFE
(1 Byte)
Status
(4+4 Bits) 1 Byte
Preamble
Header
Data
Payload
CRC
Command ID Data Payload CRC
1 Byte
From Base Station
Request Frame
Response Frame
From Transponder
CRC
(4 Bits)
Secret Key
(128 Bits)
tRXDATA_max tTXDATA_max
ATA5580 [DATASHEET]
9254E–RKE–08/14
18
2.9.5 Learn Secret Key 2
This command starts the secret key2 learning process. Depending on the configuration stored in EEPROM at address
0x811(bit 6) it is either open or secure transfer. If the bit (SKT - secure key transfer bit) is 0, the transfer is open mode and if
the bit is 1, the transfer is in secure mode. The request frame carries a 128-bit secret key data payload (may be encrypted
during secure transfer). The 128-bit key transferred through this command is stored in the AP1 key position 2 (0x780) along
with two copies. The response frame consists of a status byte at the data payload. The status byte is stored in RAM and
updated with each communication session. The status byte consists of the last command received (MS 4 bits) and an error
flag (LS 4 bits).
Status Byte [7:4]: Four MSBs of the field contain an echo of the command received in the last request frame. Status byte
[3:0]: Four LSBs of the field contain status information in encoded form.
Figure 2-12. The Learn Secret Key2 Se quence
Table 2-9. The Learn Secret Key2 (Request Frame)
Field Size Values Description
Command ID 4 + 4 bits 1000b + 1011 CRC Learn secret key2
Data payload 128 bits AES-128 (possibly
encrypted) secret key
CRC 1 byte Calculate
Table 2-10. Learn Secret Key2 (Resp onse Frame)
Field Size Values Description
Preamble header 1 byte 0xFE Synchronization
Data payload 1 byte Status Status
CRC 1 byte Calculate
0111b
(4 Bits)
0xFE
(1 Byte)
Status
(4+4 Bits) 1 Byte
Preamble
Header
Data
Payload
CRC
Command ID Data Payload CRC
1 Byte
From Base Station
Request Frame
Response Frame
From Transponder
CRC
(4 Bits)
Secret Key
(128 Bits)
tRXDATA_max tTXDATA_max
19
ATA5580 [DATASHEET]
9254E–RKE–08/14
2.9.6 Initiate Enhanced Mode
This command initializes the enhanced mode command structure and switches the transponder into enhanced mode when it
enters the VFLD the next time by setting the enhanced mode flag in EEPROM. In addition, this command begins a sequence
to place the transponder into the enhanced mode where the battery supply is used during transponder communication. An
EEPROM flag having a TBD value is stored at the TBD address. The address is checked at each POR to determine if the
power switch should be disabled. Once the flag is set by this LF command, the NEXT power cycle causes the following LF
session to be operated using battery power. It occurs only once each time this LF command is received.
The status byte consists of the last command received (MS 4 bits) and an error flag (LS 4 bits).
Status byte [7:4]: Four MSBs of the field contain an echo of the command received in the last request frame. Status byte
[3:0]: Four LSBs of the field contain status information in encoded form.
Figure 2-13. The Initiate Enhanced Mode Sequence
Table 2-11. The Initiate Enhanced Mode (Request Frame)
Field Size Values Description
Command ID 4 + 4 bits 0011b + 0101 CRC Initiate enhanced mode
Data payload N/A
CRC N/A
Table 2-12. The Initiate Enhanced Mo de (Response Frame)
Field Size Values Description
Preamble header 1 byte 0xFE Synchronization
Data payload 1 byte Status Status
CRC 1 byte Calculate
0011b
(4 Bits)
0xFE
(1 Byte)
Status
(4+4 Bits) 1 Byte
Preamble
Header
Data
Payload
CRC
Command ID
From Base Station
Request Frame
Response Frame
From Transponder
CRC
(4 Bits)
tRXDATA_max tTXDATA_max
ATA5580 [DATASHEET]
9254E–RKE–08/14
20
2.9.7 Repeat Last Response
This command requests that the last transmission is repeated and quickly repeats the last response used. It enables a retry
strategy that increases communication response time.
The response frame matches the response from the previous command.
Figure 2-14. The Repeat Last Response Sequence
Table 2-13. Repeat Last Response (Request Frame)
Field Size Values Description
Command ID 4 + 4 bits 1110b + 0001 CRC Repeat last response
Data payload N/A
CRC N/A
Table 2-14. Repeat Last Response (Res ponse Frame)
Field Size Values Description
Preamble header 1 byte 0xFE Synchronization
Data payload Varies Status
CRC 1 byte Calculate
1110b
(4 Bits)
0xFE
(1 Byte) 1 ByteVaries
Preamble
Header
Data
Payload
CRC
Command ID
From Base Station
Request Frame
Response Frame
From Transponder
CRC
(4 Bits)
tRXDATA_max tTXDATA_max
21
ATA5580 [DATASHEET]
9254E–RKE–08/14
2.9.8 Read User Memory
This command provides memory read operation from the user memory (EEPROM). The request frame data block provides
the beginning address of the EEPROM as well as the read length (the number of bytes that should be read). Addresses in
the (0x0780 to 0x07FF) or (0x0817 to 0x0826) ranges should NEVER be allowed access via the memory access commands.
The transponder provides the status byte as well as the requested number of EEPROM data bytes in the response frame.
The response length specified does not exceed 16 bytes. The status byte consists of the last command received (MS 4 bits)
and an error flag (LS 4 bits).
Status byte [7:4]: Four MSBs of the field contain an echo of the command received in the last request frame. Status byte
[3:0]: Four LSBs of the field contain status information in encoded form.
Figure 2-15. The Read User Memory Sequence
Table 2-15. Read User Memory (Request Frame)
Field Size Values Description
Command ID 4 + 4 bits 0100b + 1100 CRC Read user memory
Data payload 2 bytes + 1 byte EEPROM address + data
length
CRC 1 byte Calculate
Table 2-16. Read User Memory (Respons e Frame)
Field Size Values Description
Preamble header 1 byte 0xFE Synchronization
Data payload 1 byte + data Status + data Status + EEPROM data
CRC 1 byte Calculate
0100b
(4 Bits)
0xFE
(1 Byte) 1 ByteStatus+Data
EEPROM Address
(2 Bytes) +Data Length
(1 Byte)
Preamble
Header
Data
Payload
CRC
Command ID Data Payload CRC
1 Byte
From
Base Station
Request
Frame
Response Frame
From Transponder
CRC
(4 Bits)
tRXDATA_max tTXDATA_max
ATA5580 [DATASHEET]
9254E–RKE–08/14
22
2.9.9 Write User Memory
This command provides write operation to the user memory (EEPROM). The request frame data block provides the
beginning address of the EEPROM followed by the data to be written. The transponder provides the status of the result in
the response frame. Write commands that involve transponder EEPROM addresses with the AP1, AP2 and AP3 sections
initially check the saved lock state for this section. If the section has previously been locked, the command is aborted and the
transponder sends an error response. During normal operation the number of EEPROM data bytes to be written should be 4
bytes at the most. During enhanced mode the number of EEPROM data bytes to be written should not exceed 128 bytes.
The EEPROM data is always sent as complete bytes.
The status byte consists of the last command received (MS 4 bits) and an error flag (LS 4 bits).
Status byte [7:4]: Four MSBs of the field contain an echo of the command received in the last request frame. Status byte
[3:0]: Four LSBs of the field contain status information in encoded form.
Figure 2-16. The Write User Memory Sequ ence
Table 2-17. Write User Memory (Requ est Frame)
Field Size Values Description
Command ID 4 + 4 bits 0101b + 1111 CRC Read user memory
Data payload 16 bits + 1 to 4 bytes + 8 bits EEPROM address + data
lock
CRC 1 byte Calculate
Table 2-18. Write User Memory (R esponse Frame)
Field Size Values Description
Preamble header 1 byte 0xFE Synchronization
Data payload 1 byte Status Status byte
CRC 1 byte Calculate
0101b
(4 Bits)
0xFE
(1 Byte)
Status
(4+4 Bits) 1 Byte
EEPROM Address
(16 Bits) +Data
(8 to 32 Bits) + Lock (8 Bits)
Preamble
Header
Data
Payload
CRC
Command ID Data Payload CRC
1 Byte
From
Base Station
Request
Frame
Response Frame
From Transponder
CRC
(4 Bits)
tRXDATA_max tTXDATA_max
23
ATA5580 [DATASHEET]
9254E–RKE–08/14
2.9.10 Write Memory Access Protection
This command protects only the AP1, AP2 and AP3 sections from being overwritten through transponder memory access
commands (LF field commands). Once protection has been applied, it is not removed (sending 00b does not clear the locks).
The request frame data block consists of binary 00+AP3+AP2+AP1 to create one byte. To lock each section the command
transmits b11 in that section and b00 if section locking is not required (ex. 00110011 locks AP3 and AP1 and leaves section
AP2 unlocked). The use of two bits for each memory section protects against accidental locking due to one-bit corruption.
The status byte consists of the last command received (MS 4 bits) and an error flag (LS 4 bits).
Status byte [7:4]: Four MSBs of the field contain an echo of the command received in the last request frame. Status byte
[3:0]: Four LSBs of the field contain status information in encoded form.
Figure 2-17. The Write Memory Access Protection Sequence
Table 2-19. Write Memory Access Protection (Request Frame)
Field Size Values Description
Command ID 4 + 4 bits 0110b + 1010 CRC Write memory access
protection
Data payload 1 byte Protection scheme
CRC 1 byte Calculate
Table 2-20. Write Memory Access Protection (Response Frame)
Field Size Values Description
Preamble header 1 byte 0xFE Synchronization
Data payload 1 byte Status Status byte
CRC 1 byte Calculate
0110b
(4 Bits)
0xFE
(1 Byte)
Status
(4+4 Bits) 1 Byte
Preamble
Header
Data
Payload
CRC
Command ID Data Payload CRC
1 Byte1 Byte
From Base Station
Request Frame
Response Frame
From Transponder
CRC
(4 Bits)
tRXDATA_max tTXDATA_max
ATA5580 [DATASHEET]
9254E–RKE–08/14
24
2.9.11 Leave Enhanced Mode
This command clears the enhanced mode flag from EEPROM.
If the transponder receives the command “leave enhanced mode,” the internal power switch inside the transponder front end
is enabled. If the LF field is active, the internal power management automatically switches to the field-supplied mode. This
then generates a power-on reset and the immobilizer firmware is then executed.
2.10 Communication Integrity and Error Mitigation
The commands are protected from transmission channel corruption by the use of a CRC nibble. It prevents accidental
processing of an unintended command due to bit corruption. The data can be protected through a second CRC byte. This is
true for communication in both the uplink and downlink direction. The use of fast detection of bit-level corruption allows a
highly efficient retry strategy to be implemented. When this is combined with the “Repeat Last Response” command, uplink
errors can be quickly and automatically mitigated.
The following is suggested as means of progressive retries for downlink errors:
●Error detected on downlink communication due to error signal response
●Request status byte to determine the cause of error
●Resend downlink request if error was due to failed downlink CRC
●If error still persists, reset transponder completely via command or removing of LF field
The following is suggested as a means of progressive retries for uplink errors:
●Error detected on uplink communication via failed CRC check
●Request repeat transmission with “Repeat Last Response” command
●If error still occurs, repeat complete communication by resending the desired command request frame
●If error still persists, reset transponder completely via command or by removing LF field
Table 2-21. Leave Enhanced Mode (Request Frame)
Field Size Values Description
Command ID 4 + 4 bits 1010b + 1101b CRC Leave enhanced mode
Data payload N/A
CRC N/A
Table 2-22. Leave Enhanced Mo de (Response Frame)
Field Size Values Description
Preamble header 1 byte 0xFE Synchronization
Data payload 1 byte Status [7:4] previous command
[3:0] encoded error info
CRC 1 byte Calculate
25
ATA5580 [DATASHEET]
9254E–RKE–08/14
3. Immobilizer Functionality
This section describes the steps required to implement the immobilizer system functionality. The functionality can be
achieved in the base station and vehicle controller by using features and commands provided by Atmel®. The following
sections recommend how this can be achieved.
3.1 Authentication
The core purpose of the vehicle immobilizer is its ability to identify the user as somebody authorized to start the vehicle.
There are many different authentication schemes. Each has different effects on response time and security. In order to
provide the customer with a wide array of options, Atmel has developed a command and feature set that provides a high
level of configurable authentication options including the choice of either unilateral or bilateral means of authentication.
3.1.1 Unilateral Authentication
Unilateral authentication is a strategy where authentication is performed by only one entity in the system. The other entity
simply responds to any command that it receives. In the case of a vehicle immobilizer system, the vehicle attempts to verify
the identity of the key fob. The benefit of this approach is that a high level of security can be achieved without sacrificing
system response time.
Unilateral authentication should be initiated by the base station and conform to the following sequence:
1. The base station sends the “read UID” LF request.
2. The transponder responds by providing the 32-bit UID in its “response frame.”
3. The base station then sends the “start authentication” request including a random number “challenge.”
4. The transponder returns an “encrypted response” message to the base station.
Notes: 1. The “challenge” uses the bit length defined by configuration memory address 0x0819.
2. The secret key can be either key1 or key2, as defined by configuration memory address 0x0815 bit 5.
3. The “response” uses the bit length defined by configuration memory address 0x081A.
4. When necessary for encryption, the challenge is extended by first padding the upper bit positions with the
32-bit UID, then with “0”s as needed, and in this order, to reach 128 bits.
A graphical example is shown in Figure 3-1 on page 26.
ATA5580 [DATASHEET]
9254E–RKE–08/14
26
Figure 3-1. Unilateral Authentication Protocol
3.1.1.1 Read UID
The “Read UID” command has been optimized to enhance the speed of the authentication. The request from the vehicle
consists only of 8 bits. The response contains a 32-bit unique serial number that can be used for rough authentication to
determine if this key is potentially paired with the vehicle.
3.1.1.2 Start Authentication
The encrypted authentication is initiated with the start authentication request that provides the challenge data. Atmel®
recommends choosing 104 bits or 128 bits for the challenge length. The encrypted response should be chosen as 56 bits or
80 bits respectively. The reason for these choices would be to achieve a high level of security while optimizing the speed for
communication as whole. The total number of bits transferred is 188 and 240 respectively. This works out to a bit-security
level of 50 bits and 64 bits for these two options. The attacker would need to attempt more than one trillion trials to break the
security. The 128-bit secret key that is used can be chosen from one of two possible locations.
ID
Memory
Key
Memory
Key
Memory
ID
ID N
Y
N
Y
Challenge
Response
AES-128
Encryption
Challenge
Response
LF Field ON
Read UID
Stop
Stop
Valid
=
CarKey
Ok?
Random Number
AES-128
Encryption
Detection Header
(Optional)
4-bit Command
+ 4-bit CRC
8-bit Header
+ 32-bit ID
+ 8-bit CRC
8-bit Command
+ N Challenge Bits
+ 8-bit CRC
8-bit Header
+ M Response Bits
+ 8-bit CRC Ok, it is the
Right Key
Start Authentication
Command
Read UID
Command
27
ATA5580 [DATASHEET]
9254E–RKE–08/14
3.1.2 Bilateral Authentication
Bilateral authentication is a strategy where authentication is performed by both entities in the system. Each side attempts to
ensure that they are only communicating with an approved and previously paired system entity. In the case of a vehicle
immobilizer system, the transponder first verifies that the vehicle is approved. Once this has been established, the
transponder provides the means for the vehicle to verify that the transponder is approved. The benefit of the approach is that
a mutually secure system can be achieved within a reasonable system response time. It also provides the transponder with
a way to detect and repel attacks from “unapproved” base stations.
Bilateral authentication should be initiated by the base station and conform to the following sequence:
1. The base station sends the “Read UID” LF command.
2. The transponder responds by providing the 32-bit UID in its “response frame.”
3. The base station sends the “Start Authentication” LF command, which includes a random number “challenge”
followed by an AES-128 encrypted version of the “challenge” using one of its two secret keys.
4. The transponder checks the “encrypted challenge” to verify it matches the transponder’s calculated value for
“encrypted challenge” (using the same secret key that created the “encrypted challenge” in the base station).
5. The transponder creates an “encrypted response” if the verification in step 4 was successful. It uses the full 128-
bit “encrypted challenge” and not just the subset sent from the base station and the other of the two secret keys as
AES-128 block cipher inputs to form the encrypted “response.”
6. The base station compares the transponder’s “encrypted response” with its calculated value for encrypted
“response” following the same process used in step 5. If they match, bilateral authentication was successful.
Notes: 1. The “challenge” uses the bit length defined by configuration memory address 0x0819.
2. The initial secret key can be either key1 or key2 as defined by configuration memory address 0x0815 bit 5.
3. The “encrypted challenge” and “encrypted response” have their bit length defined by configuration memory
address 0x081A.
4. The other secret key is used to create the “encrypted response.”
5. When necessary, inputs for calculating the “encrypted challenge” and “encrypted response” are extended by
first padding the upper bit positions with the 32-bit UID, then with “0”s as needed, and in this order, to attain 128
bits.
A visual representation is noted in Figure 3-2 on page 28.
ATA5580 [DATASHEET]
9254E–RKE–08/14
28
Figure 3-2. Authentication BA
3.1.3 Read UID
The “Read UID” command has been optimized to enhance the speed of the authentication. The request from the vehicle
consists only of 8 bits. The response contains a 32-bit unique serial number that can be used for rough authentication to
determine if this key is potentially paired with the vehicle.
3.1.4 Start Authentication
The “Start Authentication” command begins with sending a challenge followed by the output of an encryption of the
challenge with an initial secret key. This “encrypted challenge” authenticates vehicle identity to the transponder and proves
that the vehicle is a valid partner with whom the transponder can communicate. The lengths of both of these are adjustable
in the configuration options, but Atmel recommends that a challenge length of 104 bits and encrypted challenge of 56 bits. If
if fails, the transponder simply sends an error signal back. If the vehicle is successfully authenticated, the transponder
calculates the response to the vehicle using the hidden challenge and the remaining secret key. This is the same length as
the “encrypted challenge” and we recommend setting it to 56 bits.
The response can be evaluated by the vehicle to determine authenticity of the transponder. The total number of bits
transferred is 244 and provides a bit security level of 50. This approach is also strengthened by the use of two separate 128-
bit secret keys. Each secret key protects one direction of authentication meaning that compromising one secret key does not
break the complete bilateral authentication protocol.
AES-128
Encryption
AES-128
Encryption
Key 1
Memory
ID
Memory
Key 2
Memory
Challenge
Random Number
ID
NY
N
Y
Stop
AES-128
Encryption
AES-128
Encryption
Key 1
Memory
Key 2
Memory
Challenge
Detection Header
(Optional)
4-bit Command
+ 4-bit CRC
8-bit Header
+ 32-bit ID
+ 8-bit CRC
8-bit Command
+ N-bit Rand N
+ M-bit (Rand N)AES
+ 8-bit CRC
8-bit Header
+ M bit (Response)AES
+ 8-bit CRC
LF Field ON
ID
Read UID
Stop
Valid
=
=
Key Car
Read UID
Command
Hidden
Challenge (HCH)
Expanded to 128 Bits
Hidden
Challenge (HCH)
Expanded to 128 Bits
Ok, it is the
Right Key,
Car and Key
Match
Ok, it is the
Right Car,
Continue
Start Authentication
Command
29
ATA5580 [DATASHEET]
9254E–RKE–08/14
3.1.5 Hidden Challenge
Another aspect of this protocol is the use of a “hidden” challenge as the input to the second encryption stage. The reason the
challenge is considered “hidden” is that only a portion of this value is ever transmitted over the wireless interface. Using the
recommended values from above, we see that the input to the second encryption block contains the 56-bit “encrypted
challenge” that was used to determine the authenticity of the vehicle. While this value is sent over the air and could be
recorded, the second encryption block requires that the complete 128-bit output of the first encryption be known precisely.
Since only 56 bits could be captured, this leaves 72 bits that are “hidden” from the attacker but are critical to producing the
correct output. Through this scheme we are able to allow a truncated initial challenge to be expanded to a full 128-bit AES-
128 operation when producing the response used to validate the transponder identity. This final step is what protects against
unauthorized vehicle starts, which our system provides maximum protection against.
3.2 Memory Access
General purpose memory is a very important part of an immobilizer system. Atmel® has provided a large EEPROM section in
hardware and a very efficient means of accessing this through LF commands. The block size for access is flexible and
allows the end-system designer to build structures that are optimized for the data content. The only areas that are not
accessed through the memory commands are the AP0 section used for secret keys and the default secret key stored in
EEPROM page 2. All other memories providing an interface for the vehicle to interact with application functionality can be
accessed. For example, the vehicle can re-synchronize with the RKE rolling code counter, readout user-specific information,
or store diagnostic trouble codes.
For enhanced security, if the transponder is configured to use bilateral authentication, an authentication session must be
successfully accomplished before any memory access command is possible.
3.2.1 Read Memory
To read user memory only requires that the starting address and the number of bytes requested are provided. This allows
block sizes from one byte to 16 bytes to be accessed from the transponder non-volatile memory. The memory is accessed
and the data returned starting with the first address and incrementing sequentially until all bytes are sent.
The flexibility of this command means it can be used for many functions that would normally require a dedicated LF
command. Examples are shown in other sections of this document.
Figure 3-3. Read Memory
ATA5580 [DATASHEET]
9254E–RKE–08/14
30
3.2.2 Write Memory
Writing data into the memory requires the starting address to be provided followed by the number of data bytes to be stored.
The length of the block is limited to four bytes (128 bytes in enhanced mode) and must always be sent as full 8-bit multiples.
Before the memory location is written, the firmware checks to see if access protection applies and determines if this
command is allowed. Only if these checks are successful, the data is written into EEPROM.
Figure 3-4. Write Memory
Address
(16b)
Address
(16b)
1
EEPROM
2
N
Address
Protected?
Data 1
(8b)
Data 2
(8b)
Data N
(8b)
Data 1
(8b)
Data 2
(8b)
Data N
(8b)
Status Response
(Pass/Fail/Locked)
Status Response
(Pass/Fail/Locked)
Write User Memory Write User
Memory
Yes
LF Field ON
Key Car
Detection Header
(Optional)
8-bit Command
+ 16-bit Address
+ 8-bit Length
+ Data Contents
+ 8-bit CRC
8-bit Header
+ 8-bit Status
+ 8-bit CRC
Write User
Memory
Command
Address
Should be
Less Than
AP0
31
ATA5580 [DATASHEET]
9254E–RKE–08/14
3.2.3 Memory Protec t io n
Memory protection provides a means to prevent EEPROM data from being modified by future LF commands. Once the
protection is applied, it cannot be removed by a subsequent LF command. The protection applies to a complete section of
EEPROM. There are three EEPROM sections that can be used. They are defined as the AP1, AP2, and AP3 portions of
EEPROM and contain 128 bytes in each section. One example of this could be a block of manufacturing process information
programmed into AP1 and locked so that it cannot be modified by LF commands. This allows a returned device to be traced
back through the precise manufacturing chain.
The locking feature is implemented in firmware and does not contain any hardware components. The protection applies to
the reaction to LF commands received by the immobilizer.
The write memory access protection command requires only one byte with the protection assigned to each section. Two bits
are used for each memory section to add extra protection against false locking scenarios. Both bits must be set to logical
one for the protection to be invoked. All unused locations that do not change the currently invoked protection should be set to
logic zero.
Figure 3-5. Write Memory Protection
Note: Lock bits are only written to EEPROM if the lock bits are set to “11”.
Lock bits set to “00” do NOT clear previously set bits, i.e., XOR with current EEPROM data.
3.2.4 Memory Encrypt io n
Encryption of the data is not provided through a special command or the immobilizer firmware. With the hardware encryption
block, the need for this functionality can be implemented before the data is placed in the non-volatile memory by the
application or before it is sent from the base station. Memory encryption can be easily decrypted by the application before it
is used. For example, a rolling code counter can be encrypted and stored in memory. Each time this is required, the
application decrypts it, uses the counter, increments it, encrypts the new count, and then stores it back into the memory.
EEPROM
Lock Bit Address
Lock Bits
Status Response (Pass/Fail)
Write Memory Protection
Status Response (Pass/Fail)
LF Field ON
Key Car
Detection Header
(Optional)
8-bit Command
+ 8-bit Protection
+ 8-bit CRC
8 bit-Header
+ 8-bit Status
+ 8-bit CRC
00
(2b)
AP1
(2b)
AP2
(2b)
AP3
(2b)
00
(2b)
AP1
(2b)
AP2
(2b)
AP3
(2b)
Write Memory Protection
Write Memory
Access Protection
Command
ATA5580 [DATASHEET]
9254E–RKE–08/14
32
3.3 Identification
One of the primary goals of the immobilizer is to establish the verified identity of the user. The firmware provided by Atmel®
offers many identification options allowing the system to be optimized. The following sections describe how the fixed
identification aspects can be used. Customized identification scenarios are possible by using the memory access commands
and custom block sizes as required.
3.3.1 Serial Number
The serial number is a fixed-value programmed and locked by Atmel during manufacturing. This value is a 32-bit, non-
sequential, non-repeating number and is optimized for fast initial identification. A dedicated LF command (Read UID) allows
the value to be accessed prior to authentication for a very rough screening of users.
3.3.2 Atmel Traceability
Atmel provides manufacture traceability from our process flow to directly identify a given device. This information is fixed and
locked at the end of our manufacture line. It provides very useful information about the device and also uniquely associates
it with a physical die location on a wafer. Each of the following pieces of information can be accessed individually or as a unit
with the “Read Memory” command.
●Device type: contains information that specifies which Atmel device this is
●Lot number: specifies the Atmel facility and the production lot run that created this device
●Wafer number: designates the physical wafer in this lot
●Die number: locates the die on the wafer
●Software rev: indicates the firmware release version that is currently running
33
ATA5580 [DATASHEET]
9254E–RKE–08/14
3.4 Personalization
Personalization refers to the process of setting or resetting the initial parameters of the device. In the case of the immobilizer
this involves pairing the transponder with the vehicle. The most common pairing scenario is the transfer of the secret key(s)
from the vehicle to the transponder. Other personalization parameters can be set with the “Write Memory” command. These
could be the initial roll code, application feature configuration, vehicle VIN, etc. The following section presents the options
possible for secret key transfer.
3.4.1 Open Key Learn
If the security of the key transfer can be ensured through physical or other security methods, it may be desirable to send the
secret key in plain text. The firmware can be configured to allow this and the following sequence would occur:
●The base station sends 128 bits of secret key coding to be stored using the learn secret key command.
●The transponder stores the encoded key in the AP0 section of EEPROM in key position 1 or 2.
Figure 3-6. Open Key Learn 1/2
Key
Memory
Key
Memory
N
Y
Pass
LF Field ON
Stop
=
CarKey
Random Number
Secret KeySecret Key
Response (Pass/Fail)
Detection Header
(Optional)
8-bit Header
+ 8-bit Status
+ 8-bit CRC
Learn Secret
Key (1 or 2)
Command
8-bit Command
+ 128-bit Key
+ 8-bit CRC
ATA5580 [DATASHEET]
9254E–RKE–08/14
34
3.4.2 Secure Key Le arn
Because the encryption key protects the integrity of the authentication process, Atmel® has provided a means to transfer the
secret key in an encrypted manner. This involves the use of the default secret key stored in EEPROM page 2 and protects
against eavesdropping by an attacker during key transfer. As a result, secure implementation of user-initiated
personalization is possible where physical security cannot be ensured.
●The base station sends 128 bits of data that have been encrypted using the default key stored in EEPROM page 2.
●The transponder decodes this to produce the secret key to be stored.
●The transponder then stores the encoded key in the AP0 section of EEPROM in key position 1 or 2.
Figure 3-7. Secure Key Learn
Key
Memory
Default
Key
Key
Memory
Default
Key
N
Y
Pass
AES-128
(Dec.)
LF Field ON
Stop
=
CarKey
Random Number
Encrypted KeyEncrypted Key
Secret Key
Secret Key
Response (Pass/Fail)
AES-128
Encryption
Detection Header
(Optional)
8-bit Header
+ 8-bit Status
+ 8-bit CRC
Learn Secret
Key (1 or 2)
Command
8-bit Command
+ (128-bit Key)AES
+ 8-bit CRC
35
ATA5580 [DATASHEET]
9254E–RKE–08/14
4. Abbreviations
FDX – Full duplex
AM – Amplitude modulation
BCM – Body control module
ECU – Electronic control unit
BPLM – Binary pulse length modulation
QPLM – Quad pulse length modulation
POR – Power on reset
TIC – Transmitter ID code
RKE – Remote keyless entry
DPS – Damped phase synchronized
VFLD – Field voltage
5. Absolute Maximum Ratings
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating
only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of this
specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Parameters Symbol Value Unit
Operating temperature range Tamb –40 to +85 °C
Storage temperature range (data retention reduced) Tamb –40 to +125 °C
Maximum assembly temperature, t < 5min Tass 170 °C
Magnetic field strength at f = 125kHz Hpp 1000 A/m
ATA5580 [DATASHEET]
9254E–RKE–08/14
36
6. Operating Characteristics
Tamb = +25°C; fcoil = 125kHz; unless otherwise specified.
No. Parameters Test Conditions Symbol Min. Typ. Max. Unit Type*
1Coil inductance L2.38 mH Q
2.1 LC circuit Hpp = 14.5A/m fres 119 125 131 kHz T
2.2 Hpp = 1.5A/m QLC 15 20 TBD 1 T
3Min. field for read mode (modulation) Read mode Hpp mod 35 A/m T
4Min. field for write mode Write mode Hpp prog 58 A/m T
5Maximum field strength –40°C to +85°C Hpp max 500 A/m Q
6Data retention time EEPROM Tamb = 25°C Hpp mod 20 year Q
7Write endurance EEPROM Tamb = 25°C Hpp prog 100k cycle Q
8Accuracy of internal timing references
(SRC, FRC oscillators) –40°C to +85°C Hpp max ±10 % Q
9Clock cycle 1 / fAFE TAFE 8µs
10 Field clock cycle CLKFC 125 kHz
11 Transponder data rate Read mode 3.9 kb/s
12 Transponder data rate BPLM – write mode
QPLM – write mode
4.46
5.43 kb/s
13 Start-up time 3.2VP / 125kHz 0.35 0.8 ms A
14 Transponder charge initial time tTpinit 128 TAFE T
15 Transponder mode voltage check interval tCharge 128 TAFE T
16 Bit half period (damped – talk back mode) 16 TAFE
17 Bit half period (undamped – talk back mode) 16 TAFE
18 Bit period (talk back mode) 32 TAFE
19 Gap period (write mode) Gap time
Start gap time
tGAP
tSG
10 20 TAFE D
20 Bit period
(binary “0” – write mode) BPLM – mode 24 TAFE
21 Bit period
(binary “1” – write mode) BPLM – mode 32 TAFE
22 Two bits period
(binary “00” – write mode) QPLM – mode 28 TAFE
23 Two bits period
(binary “01” – write mode) QPLM – mode 40 TAFE
24 Receive to transmit time tRXData_max 3.6 4.5 ms Q
25 Receive to receive time tTXData_max 280 350 µs Q
*) Type means: A = 100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter,
T: directly or indirectly tested during production; Q: guaranteed based on initial product qualification data
37
ATA5580 [DATASHEET]
9254E–RKE–08/14
8. Package Information
7. Ordering Information
ATA5580M nnn -TSMW Package Remarks
132 Brick tag package UA, BPLM, Manchester, RF/32, 32b Ch, 32b Rs
156 Brick tag package UA, BPLM, Manchester, RF/32, 104 Ch, 56b Rs
264 Brick tag package BA, BPLM, Manchester, RF/32, 64b Ch, 64b Rs
256 Brick tag package BA, BPLM, Manchester, RF/32, 104 Ch, 56b Rs
300 to 999 Brick tag package Customer-defined product. Must submit complete
configuration memory map
COMMON DIMENSIONS
(Unit of Measure = mm)
Package Drawing Contact:
packagedrawings@atmel.com
GPC
SYMBOL MIN NOM MAX NOTE
2.9A 33.1
0.35A3 0.4 0.45
11.9D 12 12.1
5.9E 66.1
DRAWING NO.
REV. TITLE
6.549-5036.01-4 1
12/14/11
Package: Brick Transponder
, ATA5580
Dimensions in mm
specifications
according to DIN
technical drawings
orientation feature
D
E
A3
A
E
ATA5580 [DATASHEET]
9254E–RKE–08/14
38
9. 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
9254E-RKE-08/14 Put datasheet in the latest template
9254D-RKE-11/12 Language corrections
9254C-RKE-09/12
Table 2-5 “Start Authentication (Request Frame)” on page 16 changed
Section 3.1.1.2 “Start Authentication” on page 26 changed
Section 3.1.4 “Start Authentication” on page 28 changed
Section 7 “Ordering Information” on page 37 changed
9254B-RKE-05/12
Section 2.7 “LF Physical Layer” on pages 11 to 13 changed
Section 6 “Operating Characteristics” on page 36 changed
X
XXX
XX
Atmel Corporation 1600 Technology Drive, San Jose, CA 95110 USA T: (+1)(408) 441.0311 F: (+1)(408) 436.4200 | www.atmel.com
© 2014 Atmel Corporation. / Rev.: 9254E–RKE–08/14
Atmel®, Atmel logo and combinations thereof, Enabling Unlimited Possibilities®, and others are registered trademarks or trademarks of Atmel Corporation in U.S. and
other countries. 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. EXCEPT AS SET FORTH IN THE ATMEL TERMS AND CONDITIONS OF SALES LOCATED ON THE
ATMEL WEBSITE, ATMEL ASSUMES NO LIABILITY WHATSOEVER AND DISCLAIMS ANY EXPRESS, IMPLIED OR STATUTORY WARRANTY RELATING TO ITS PRODUCTS
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. IN NO EVENT
SHALL ATMEL BE LIABLE FOR ANY DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE, SPECIAL OR INCIDENTAL DAMAGES (INCLUDING, WITHOUT LIMITATION, DAMAGES
FOR LOSS AND PROFITS, BUSINESS INTERRUPTION, OR LOSS OF INFORMATION) ARISING OUT OF THE USE OR INABILITY TO USE THIS DOCUMENT, EVEN IF ATMEL HAS
BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. Atmel makes no representations or warranties with respect to the accuracy or completeness of the contents of this
document and reserves the right to make changes to specifications and products descriptions at any time without notice. Atmel does not make any commitment to update the information
contained herein. Unless specifically provided otherwise, Atmel products are not suitable for, and shall not be used in, automotive applications. Atmel products are not intended,
authorized, or warranted for use as components in applications intended to support or sustain life.
SAFETY-CRITICAL, MILITARY, AND AUTOMOTIVE APPLICATIONS DISCLAIMER: Atmel products are not designed for and will not be used in connection with any applications where
the failure of such products would reasonably be expected to result in significant personal injury or death (“Safety-Critical Applications”) without an Atmel officer's specific written
consent. Safety-Critical Applications include, without limitation, life support devices and systems, equipment or systems for the operation of nuclear facilities and weapons systems.
Atmel products are not designed nor intended for use in military or aerospace applications or environments unless specifically designated by Atmel as military-grade. Atmel products are
not designed nor intended for use in automotive applications unless specifically designated by Atmel as automotive-grade.
Mouser Electronics
Authorized Distributor
Click to View Pricing, Inventory, Delivery & Lifecycle Information:
Atmel:
ATA5580M132-TSMW ATA5580M156-TSMW ATA5580M256-TSMW ATA5580M264-TSMW