SAM7S256_14 Datasheet, PDF (112/775 Pages) ATMEL Corporation – ARM-based Flash MCU

When programming is complete, the bit FRDY bit in the Flash Programming Status Register (MC_FSR) rises. If an
interrupt has been enabled by setting the bit FRDY in MC_FMR, the interrupt line of the Memory Controller is
activated.
Two errors can be detected in the MC_FSR register after a programming sequence:
• Programming Error: A bad keyword and/or an invalid command have been written in the MC_FCR register.
• Lock Error: At least one lock region to be erased is protected. The erase command has been refused and no
page has been erased. A Clear Lock Bit command must be executed previously to unlock the corresponding
lock regions.
19.2.4.3 Lock Bit Protection
Lock bits are associated with several pages in the embedded Flash memory plane. This defines lock regions in the
embedded Flash memory plane. They prevent writing/erasing protected pages.
After production, the device may have some embedded Flash lock regions locked. These locked regions are
reserved for a default application. Refer to the product definition section for the default embedded Flash mapping.
Locked sectors can be unlocked to be erased and then programmed with another application or other data.
The lock sequence is:
• The Flash Command register must be written with the following value:
(0x5A << 24) | (lockPageNumber << 8 & PAGEN) | SLB
lockPageNumber is a page of the corresponding lock region.
• When locking completes, the bit FRDY in the Flash Programming Status Register (MC_FSR) rises. If an
interrupt has been enabled by setting the bit FRDY in MC_FMR, the interrupt line of the Memory Controller is
activated.
A programming error, where a bad keyword and/or an invalid command have been written in the MC_FCR register,
may be detected in the MC_FSR register after a programming sequence.
It is possible to clear lock bits that were set previously. Then the locked region can be erased or programmed. The
unlock sequence is:
• The Flash Command register must be written with the following value:
(0x5A << 24) | (lockPageNumber << 8 & PAGEN) | CLB
lockPageNumber is a page of the corresponding lock region.
• When the unlock completes, the bit FRDY in the Flash Programming Status Register (MC_FSR) rises. If an
interrupt has been enabled by setting the bit FRDY in MC_FMR, the interrupt line of the Memory Controller is
activated.
A programming error, where a bad keyword and/or an invalid command have been written in the MC_FCR register,
may be detected in the MC_FSR register after a programming sequence.
The Unlock command programs the lock bit to 1; the corresponding bit LOCKSx in MC_FSR reads 0. The Lock
command programs the lock bit to 0; the corresponding bit LOCKSx in MC_FSR reads 1.
Note: Access to the Flash in Read Mode is permitted when a Lock or Unlock command is performed.
19.2.4.4 General-purpose NVM Bits
General-purpose NVM bits do not interfere with the embedded Flash memory plane. (Does not apply to EFC1 on
the SAM7S512.) These general-purpose bits are dedicated to protect other parts of the product. They can be set
(activated) or cleared individually. Refer to the product definition section for the general-purpose NVM bit action.
The activation sequence is:
• Start the Set General Purpose Bit command (SGPB) by writing the Flash Command Register with the SEL
command and the number of the general-purpose bit to be set in the PAGEN field.
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
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