sam3s16 ATMEL Corporation, sam3s16 Datasheet - Page 27

• Manufacturer Part Number: sam3s16
• Description: At91sam Arm-based Flash Mcu
• Manufacturer: ATMEL Corporation

9.1.3.5
9.1.3.6
9.1.3.7
9.1.3.8
9.1.3.9
9.1.3.10
11117AS–ATARM–12-Jul-11
Lock Regions
Security Bit Feature
Calibration Bits
Unique Identifier
User Signature
Fast Flash Programming Interface
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.
Table 9-1.
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.
The SAM3S16 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, SRAM, Core Registers and Internal
Peripherals 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, and after a full Flash erase is performed. When the security bit is deactivated,
all accesses to the Flash, SRAM, Core registers, Internal Peripherals 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.
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.
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.
The memory has one additional reprogrammable page that can be used as a signature page by
the user. It is accessible through specific modes, for erase, write and read operations. Erase pin
assertion will not erase the User Signature page.
The Fast Flash Programming Interface allows programming the device through a multiplexed
fully-handshaked parallel port. It allows gang programming with market-standard industrial
programmers.
SAM3S16
Product
Number of Lock Bits
Number of Lock Bits
128
SAM3S16 Preliminary
Lock Region Size
8 KBytes
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