AT91SAM7SE512 datasheet(25/47 Pages) ATMEL

25 / 47 page

6222ES–ATARM–15-Dec-09

AT91SAM7SE512/256/32 Preliminary Summary

The Flash benefits from the integration of a power reset cell and from the brownout detector.

This prevents code corruption during power supply changes, even in the worst conditions.

8.1.2.2

Embedded Flash Controller

The Embedded Flash Controller (EFC) manages accesses performed by the masters of the sys-

tem. It enables reading the Flash and writing the write buffer. It also contains a User Interface,

mapped within the Memory Controller on the APB. The User Interface allows:

• programming of the access parameters of the Flash (number of wait states, timings, etc.)

• starting commands such as full erase, page erase, page program, NVM bit set, NVM bit

clear, etc.

• getting the end status of the last command

• getting error status

• programming interrupts on the end of the last commands or on errors

The Embedded Flash Controller also provides a dual 32-bit Prefetch Buffer that optimizes 16-bit

access to the Flash. This is particularly efficient when the processor is running in Thumb mode.

• Two EFCs (EFC0 and EFC1) are embedded in the SAM7SE512 to control each plane of 256

KBytes. Dual plane organization allows concurrent Read and Program.

• One EFC (EFC0) is embedded in the SAM7SE256 to control the single plane 256 KBytes.

• One EFC (EFC0) is embedded in the SAM7SE32 to control the single plane 32 KBytes.

8.1.2.3

Lock Regions

The AT91SAM7SE512 Embedded Flash Controller manages 32 lock bits to protect 32 regions

of t h e f l ash again s t inadver t ent flas h er asing or programming commands. The

AT91SAM7SE512 contains 32 lock regions and each lock region contains 64 pages of 256

bytes. Each lock region has a size of 16 Kbytes.

The AT91SAM7SE256 Embedded Flash Controller manages 16 lock bits to protect 16 regions

of t h e f l ash again s t inadver t ent flas h er asing or programming commands. The

AT91SAM7SE256 contains 16 lock regions and each lock region contains 64 pages of 256

bytes. Each lock region has a size of 16 Kbytes.

The AT91SAM7SE32 Embedded Flash Controller manages 8 lock bits to protect 8 regions of

the flash against inadvertent flash erasing or programming commands. The AT91SAM7SE32

contains 8 lock regions and each lock region contains 32 pages of 128 bytes. Each lock region

has a size of 4 Kbytes.

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

triggers an interrupt.

The 32 (AT91SAM7SE512), 16 (AT91SAM7SE256) or 8 (AT91SAM7SE32) NVM bits are soft-

ware programmable through the EFC 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.

8.1.2.4

Security Bit Feature

The AT91SAM7SE512/256/32 features a security bit, based on a specific NVM-bit. When the

security is enabled, any access to the Flash, either through the ICE interface or through the Fast

Flash Programming Interface, is forbidden.

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