AT90SC6404RT datasheet(21/65 Pages) ATMEL

21 / 65 page

Target of Evaluation Description

TPG0053A (24 Nov 04)

General Business Use

21 of 64

During the initial part of the manufacturing process, the MCU is set to test mode.

Authorized development staff then test the MCU. After testing, test mode is

permanently disabled and the MCU is set to user mode.

If a faulty MCU is returned from the field then analysis can only be done in user mode

because test mode is inhibited by sawing off the critical wires, prior to devices going to

the field.

There is no intermediate mode for fault analysis. The only modes of operation are those

stated in paragraph 56.

Once manufactured, the MCU operates by executing the smartcard embedded

software, which is stored in AVR ROM. The contents of the AVR ROM cannot be

modified, whereas the contents of the EEPROM can, in general, be written to or erased,

under the control of the smartcard embedded software.

The EEPROM includes OTP bytes, which can be used to store security-related

information such as cryptographic keys. The OTP bytes cannot be erased in user

mode.

The FireWall (Memories and Peripherals Protection Unit) allows the smartcard

embedded software to prevent read/write/execute access to (parts of) AVR ROM,

EEPROM, RAM and peripherals from EEPROM.

After an MCU reset, the contents of the RAM are initialized to a random value (except

32 bytes of protected RAM).

The ISO7816 compliant I/O port can be used to pass data to or from the MCU. The

application program determines how to interpret the data.

2.6

General IT Features of the TOE

The TOE IT functionalities consist of data storage and processing such as:

Arithmetic functions (e.g. incrementing counters in electronic purses, calculating

currency conversion in electronic purses)

Data communication

Cryptographic operations (e.g. data encryption, digital signature verification)

AT90SC6404RT датащи(PDF) 21 Page - ATMEL Corporation