AT88SC1616C ATMEL [ATMEL Corporation], AT88SC1616C Datasheet - Page 6

• Manufacturer Part Number: AT88SC1616C
• Manufacturer: ATMEL [ATMEL Corporation]

Communication
Security Modes
Table 4. Communication Security Modes
Security
Options
Anti-tearing
Write Lock
6
Mode
Standard
Authentication
Encryption
11011001
$080
AT88SC1616C
xxxx xxxx
locked
$081
Configuration Data
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 activiated by a suc-
cessful authentication sequence. Encryption mode is activated by a successful encryption
activation following a successful authentication.
Note:
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 func-
tion, 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 two-wire mode, the host is required to perform ACK polling for up to 20 ms after write com-
mands when anti-tearing is active. At power-up, the host is required to perform ACK polling, in
some cases for up to 10 ms, in the event that the device needs to carry out the data recovery
process.
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.
The write lock byte may also be locked by writing its least significant (rightmost) bit to “0”.
Moreover, when write lock mode is activated, the write lock byte can only be programmed –
that is, bits written to “0” cannot return to “1”.
In the write lock configuration, only one byte can be written at a time. Even if several bytes are
received, only the first byte will be taken into account by the device.
xxxx xxxx
locked
$082
Clear
Clear
Clear
1. Configuration data includes viewable areas of the Configuration Zone except the passwords:
MDC: Modification Detection Code.
MAC: Message Authentication Code.
(1)
xxxx xxxx
$083
xxxx xxxx
User Data
Encrypted
$084
Clear
Clear
xxxx xxxx
locked
$085
Passwords
Encrypted
Encrypted
xxxx xxxx
Clear
$086
xxxx xxxx
$087
Data Integrity Check
MDC
MAC
MAC
2030AS–09/01
$80
@