Datasheet

32
SAM3S [SUMMARY]
6500ES–ATARM–11-Feb-13
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 SAM3S 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.
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 calibration 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.
9.1.3.9 Fast Flash Programming Interface
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.
The FFPI supports read, page program, page erase, full erase, lock, unlock and protect commands.
The Fast Flash Programming Interface is enabled and the Fast Programming Mode is entered when TST is tied high and
PA0 and PA1 are tied low.
9.1.3.10 SAM-BA
®
Boot
The SAM-BA Boot is a default Boot Program which provides an easy way to program in-situ the on-chip Flash memory.
The SAM-BA Boot Assistant supports serial communication via the UART and USB.
The SAM-BA Boot provides an interface with SAM-BA Graphic User Interface (GUI).
Table 9-1. Number of Lock Bits
Product Number of Lock Bits Lock Region Size
ATSAM3S4 16 16 kbytes (64 pages)
ATSAM3S2 8 16 kbytes (64 pages)
ATSAM3S1 4 16 kbytes (64 pages)