ATSHA204 ATMEL [ATMEL Corporation], ATSHA204 Datasheet - Page 26

• Manufacturer Part Number: ATSHA204
• Description: Atmel CryptoAuthentication
• Manufacturer: ATMEL [ATMEL Corporation]

6.7
7.
7.1
7.2
I
It is possible for the system to lose synchronization with the I/O port on the ATSHA204, perhaps due a system reset, I/O noise,
or other condition. Under this circumstance, the ATSHA204 may not respond as expected, may be asleep, or may be
transmitting data during an interval when the system is expecting to send data. Any command results in the I/O buffer may be
lost when the system and device lose synchronization.
To re-synchronize, the following procedure should be followed:
Electrical Characteristics
Absolute Maximum Ratings*
Reliability
The ATSHA204 is fabricated with the high reliability of the Atmel CMOS EEPROM manufacturing technology.
Table 7-1.
2
Operating Temperature ............................... −40°C to +85°C
Storage Temperature ................................ −65°C to + 150°C
Maximum Operating Voltage ........................................ 6.0V
DC Output Current ..................................................... 5.0mA
Voltage on any pin ............................... -0.5V to (V
Parameter
Write Endurance (each byte at 25°C)
Data Retention (at 55°C)
Data Retention (at 35°C)
Read Endurance
C Synchronization
1.
2.
3.
To ensure an I/O channel reset, the system should send the standard I
If the device does not respond to the device address with an ACK, then it may be asleep. In this case, the system
If the device still does not respond to the device address with an ACK, then it may be busy executing a command.
It should then be possible to send a read sequence, and, if synchronization has completed properly, the ATSHA204
will ACK the device address. The device may return data or may leave the bus floating (which the system will
interpret as a data value of 0xFF) during the data periods.
If the device does ACK the device address, the system should reset the internal address counter to force the
ATSHA204 to ignore any partial input command that may have been sent. This can be accomplished by sending a
write sequence to word address 0x00 (Reset), followed by a stop condition.
should send a complete wake token and wait t
sequence, and, if synchronization has completed, the device will ACK the device address.
The system should wait the longest t
the device.
•
•
•
•
A start condition
Nine cycles of SCL with SDA held high
Another start condition
A stop condition
EEPROM reliability
EXEC
(max) and then send the read sequence, which will be acknowledged by
CC
+ 0.5V)
100,000
WHI
Min
10
30
after the rising edge. The system may then send another read
*Notice:
Unlimited
Typical
50
Stresses beyond those listed under “Absolute
Maximum Ratings” may cause permanent
damage to the device. This is a stress rating
only, and functional operation of the device at
these or any other condition beyond those
indicated in the operational sections of this
specification is not implied. Exposure to
absolute maximum rating conditions for
extended periods may affect device reliability.
2
C software reset sequence, as follows:
Atmel ATSHA204 [DATASHEET]
Max
8740D−CRYPTO−3/12
Write Cycles
Read Cycles
Years
Years
Units
26