ATSAM3N0BA-MU datasheet(32/60 Pages) ATMEL

32 / 60 page

11011BS–ATARM–22-Feb-12

SAM3N Summary

9.1.3.4

Flash Speed

The user needs to set the number of wait states depending on the frequency used.

For more details, refer to the AC Characteristics sub section in the product Electrical Character-

istics Section.

9.1.3.5

Lock Regions

Several lock bits used to protect write and erase operations on lock regions. A lock region is

composed of several consecutive pages, and each lock region has its associated lock bit.

If a locked-region’s erase or program command occurs, the command is aborted and the EEFC

triggers an interrupt.

The lock bits are software programmable through the EEFC User Interface. The command “Set

Lock Bit” enables the protection. The command “Clear Lock Bit” unlocks the lock region.

Asserting the ERASE pin clears the lock bits, thus unlocking the entire Flash.

9.1.3.6

Security Bit Feature

The SAM3N features a security bit, based on a specific General Purpose NVM bit (GPNVM bit

0). When the security is enabled, any access to the Flash, either through the ICE interface or

through the Fast Flash Programming Interface, is forbidden. This ensures the confidentiality of

the code programmed in the Flash.

This security bit can only be enabled, through the command “Set General Purpose NVM Bit 0” of

the EEFC User Interface. Disabling the security bit can only be achieved by asserting the

ERASE pin at 1, after a full Flash erase is performed. When the security bit is deactivated, all

accesses to the Flash are permitted.

It is important to note that the assertion of the ERASE pin should always be longer than 200 ms.

As the ERASE pin integrates a permanent pull-down, it can be left unconnected during normal

operation. However, it is safer to connect it directly to GND for the final application.

9.1.3.7

Calibration Bits

NVM bits are used to calibrate the brownout detector and the voltage regulator. These bits are

factory configured and cannot be changed by the user. The ERASE pin has no effect on the cal-

ibration bits.

9.1.3.8

Unique Identifier

Each device integrates its own 128-bit unique identifier. These bits are factory configured and

cannot be changed by the user. The ERASE pin has no effect on the unique identifier.

Table 9-1.

Lock bit number

Product

Number of lock bits

Lock region size

SAM3N4

16 kbytes (64 pages)

SAM3N2

16 kbytes (64 pages)

SAM3N1

16 kbytes (64 pages)

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