ATSHA204 ATMEL [ATMEL Corporation], ATSHA204 Datasheet - Page 36

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

8.1.5
8.1.6
Zone Encoding
The value in Param1 controls which zone the command accesses. See Section 2.1.2.1, “Configuration Zone Locking,” to
obtain more information on what controls the “locked” and “unlocked” states for each zone. All other zone values are reserved,
and should not be used.
Table 8-8.
Watchdog Failsafe
A watchdog counter starts within the device after the ATSHA204 receives a wake token. After t
sleep mode, regardless of whether some I/O transmission or command execution is in progress. There is no way to reset the
counter other than to put the device into sleep or idle mode and then wake it up again.
The watchdog timer is implemented as a failsafe mechanism so that no matter what happens on either the system side or
inside the device, including any I/O synchronization issue, power consumption will fall to the ultra-low sleep level automatically.
The device resets the values stored in the SRAM and internal status registers when it transitions to the sleep state. However, if
the device is explicitly put into the idle mode through the appropriate I/O sequence, the device retains the contents of the two
SRAM registers (TempKey and RNG seed).
Normally, all command sequences must complete within t
The system software can use this idle mode mechanism to implement a longer command sequence than can be completed
during a single watchdog interval.
Zone
Name
Config
OTP
Data
Param1
Value
0
1
2
Zone Encoding (Param1)
Size
512 bits,
64 bytes,
2 slots
512 bits,
64 bytes,
2 slots
4096 bits,
512 bytes,
16 slots
Read
Always available
Never when unlocked. Always
when locked, except in legacy
mode. See Section 2.1.3
Never when unlocked.
Otherwise, controlled by
IsSecret and EncryptRead.
WATCHDOG
if they require state that is stored in the SRAM registers.
Write
Partially, when unlocked
Never when locked
Never encrypted
All writeable when unlocked using Write
When locked, write permissions depend on OTPmode
See Section 2.1.3
All writeable when unlocked
When locked, writes controlled by WriteConfig
Atmel ATSHA204 [DATASHEET]
WATCHDOG
8740D−CRYPTO−3/12
, the device enters
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