10

5015HS–SMEM–11/08

AT88SC6416C

Figure 11. Synchronous 2-wire Protocol (Gemplus Patent)

Note:

Five clock pulses must be sent before the first command is issued.

Communication

Security Modes

Communications between the device and host operate in three basic modes. Standard mode is

the default mode for the device after power-up. Authentication mode is activated by a successful

authentication sequence. Encryption mode is activated by a successful encryption activation fol-

lowing a successful authentication.

Note:

1. Configuration data include viewable areas of the Configuration Zone except the passwords:

MDC: Modification Detection Code

MAC: Message Authentication Code.

Security

Options

Anti-tearing

In the event of a power loss during a write cycle, the integrity of the device’s stored data may be

recovered. This function is optional: the host may choose to activate the anti-tearing function,

depending on application requirements. When anti-tearing is active, write commands take longer

to execute, since more write cycles are required to complete them, and data are limited to eight

bytes.

Data are written first to a buffer zone in EEPROM instead of the intended destination address,

but with the same access conditions. The data are then written in the required location. If this

second write cycle is interrupted due to a power loss, the device will automatically recover the

data from the system buffer zone at the next power-up.

In 2-wire mode, the host is required to perform ACK polling for up to 8 ms after write commands

when anti-tearing is active. At power-up, the host is required to perform ACK polling, in some

cases for up to 2 ms, in the event that the device needs to carry out the data recovery process.

Write Lock

If a user zone is configured in the write lock mode, the lowest address byte of an 8-byte page

constitutes a write access byte for the bytes of that page.

Example: The write lock byte at $080 controls the bytes from $080 to $087.

Vcc

I/O-SDA

RST

CLK-SCL

1

2

3

45

Mode

Configuration Data

User Data

Passwords

Data Integrity Check

Standard

Clear

Clear

Clear

MDC

Authentication

Clear

Clear

Encrypted

MAC

Encryption

Clear

Encrypted

Encrypted

MAC