ATSHA204 datasheet(4/65 Pages) ATMEL

4 / 65 page

Atmel ATSHA204 [DATASHEET]

8740D

−CRYPTO−3/12

Device Organization

The device contains the following memory blocks:

• EEPROM

• SRAM

2.1

EEPROM Organization

The EEPROM contains a total of 5312 bits, and is divided into the following zones:

• Data

A 512-byte (4-Kbit) zone split into 16 general-purpose, read-only, or read/write memory slots of 32 bytes (256 bits)

each that can be used to store keys, calibration data, model number, or other information related to the item to which

the Atmel ATSHA204 device is attached. Each slot may have different access restrictions based on the values

stored in the configuration zone. Within this document the nomenclature slot[yy] indicates the 32-byte value stored in

slot yy of the data zone.

• Configuration

An 88-byte (704-bit) zone that contains serial number and other ID information as well as access permission

information for each slot of the data memory. Within this document the nomenclature SN[a:b] indicates a range of

bytes within a field of the configuration section. The 88 bytes are accessible from within a three-block address

space.

• OTP (One Time Programmable)

A 64-byte (512-bit) zone which can be used to store read-only data. Prior to locking the OTP zone, the bits may be

freely written using the standard Write command. The OTP zone is accessible from within a two-block address

space. Within this document the nomenclature OTP[bb] indicates a byte within the OTP zone, while OTP[aa:bb]

indicates a range of bytes.

Within this document, the terms “slot” and “block” are used interchangeably to mean a single, 256-bit (32-byte) area of a

particular memory zone. The industry SHA-256 documentation uses the term “block” to indicate a 512-bit section of the

message input. In addition, the I/O section of this document uses the term “block” to indicate a variable-length aggregate

element transferred between the system and the device.

Many sections of this document refer to a keyID, which is equivalent to the slot number for those slots designated to hold key

values. Key #1 (sometimes referred to as key[1]) is stored in Slot[1], and so on. While all 16 slots can potentially hold keys,

those slots for which clear reads are permitted would not normally be used as keys by the crypto commands.

In this specification, the nomenclature mode:b indicates bit b of the parameter mode.

On shipment from Atmel, the EEPROM contains factory test data that can be used for fixed-value board testing. This data

must be overwritten with the desired contents prior to locking the configuration and/or data sections of the device. See the

Atmel website for the document containing the specific shipment values.

ATSHA204 Datasheet(PDF) 4 Page - ATMEL Corporation