ATECC608A datasheet(8/81 Pages) MICROCHIP

8 / 81 page

Important: If there is no need to change the I2C address, this location must be written with the default I2C

address.

User Extra Byte

The UserExtra byte can be used for any desired purpose. This byte can be updated just once with the UpdateExtra

command. The UserExtra byte is located at byte 84 of the Configuration zone.

Counter[0,1]

While the counters are not used by this device, they are not disabled. If so desired, the monotonic counters may be

used by the system. Note that the counters are initialized to zero and can count to the maximum value of 2,097,151.

The counter value can be incremented or read through the use of the Counter command. How this counter is used

is strictly up to the system and independent of anything else on the device. Counter values can be read or updated

using the Counter command.

2.2

Data Zone and Access Policies

The following sections describe the detailed access policy information associated with each slot. The actual access

policy information is stored within the Slot and Key configuration sections in the EEPROM Configuration zone. Each

Data zone slot has two Slot Configuration Bytes and two Key Configuration Bytes associated with it. Together, these

four bytes create the “Access Policies” for each slot. The actual type of data stored within the slot is determined by

the Access Policies for that slot.

2.2.1

Data Zone Data Types

The following section provides more details on the various types of data capable of being stored in the ATECC608A-

TNGLoRaWAN data slots.

2.2.1.1

AES Key Storage

LoRa Security is built around 128-bit AES symmetric keys. A wide variety of AES keys have been implemented to

support the LoRaWAN specification in the ATECC608A-TNGLoRaWAN device. These include:

• Network and Application parent keys

• Application sessions keys

• Various types of Network and Server encryption keys

• Network and Server integrity keys

The KDF command in AES mode should be used to generate the necessary LoRaWAN session keys based on the

AES parent keys stored in Slot 0. Optionally, these keys can be written as clear text. These keys are still considered

secret and therefore can only be read via an encrypted read.

2.2.1.2

IEEE EUI-64 Identifier

The IEEE Extended Unique Identifier (EUI) is an 8-byte binary or hexadecimal value, which in this case, is used as a

Device EUI to uniquely identify a LoRaWAN node. This globally unique Device EUI (DevEUI) is assigned and written

into Slot 10 of the ATECC608A-TNGLoRaWAN. The DevEUI would be part of the reconstructed X.509 Certificate.

For the ATECC608A-TNGLoRaWAN the IEEE EUI will be assigned by Microchip.

For the ATECC608A-TNGLoRaWAN, the 8-byte DevEUI is actually stored as a 16-byte ASCII-Hex value. Every digit

of the hex EUI byte is represented by an ASCII character equivalent to its hexadecimal numerical value.

EUI-64 Identifier Example

The EUI-64 value is specified as an 8-byte hexadecimal value.

The individual hex digits are interpreted as ASCII characters

ATECC608A-TNGLoRaWAN

EEPROM Memory and Data Zone Access Policies

Complete Datasheet

DS40002154B-page 8

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