AT91SAM7S32-AI ATMEL [ATMEL Corporation], AT91SAM7S32-AI Datasheet - Page 97

• Manufacturer Part Number: AT91SAM7S32-AI
• Description: AT91 ARM Thumb-based Microcontrollers
• Manufacturer: ATMEL [ATMEL Corporation]

General-purpose NVM
Bits
Security Bit
6071A–ATARM–28-Oct-04
General-purpose NVM bits do not interfere with the embedded Flash memory plane. These
general-purpose bits are dedicated to protect other parts of the product. They can be set (acti-
vated) or cleared individually. Refer to the product definition section for the general-purpose
NVM bit action.
The activation sequence is:
•
•
Two errors can be detected in the MC_FSR register after a programming sequence:
•
•
It is possible to deactivate a general-purpose NVM bit set previously. The clear sequence is:
•
•
Two errors can be detected in the MC_FSR register after a programming sequence:
•
•
The Clear General-purpose Bit command programs the general-purpose NVM bit to 1; the cor-
responding bit GPNVMx in MC_FSR reads 0. The Set General-purpose Bit command
programs the general-purpose NVM bit to 0; the corresponding bit GPNVMx in MC_FSR
reads 1.
Note:
The goal of the security bit is to prevent external access to the internal bus system. JTAG,
Fast Flash Programming and Flash Serial Test Interface features are disabled. Once set, this
bit can be reset only by an external hardware ERASE request to the chip. Refer to the product
definition section for the pin name that controls the ERASE. In this case, the full memory plane
is erased and all lock and general-purpose NVM bits are cleared. The security bit in the
MC_FSR is cleared only after these operations.
The activation sequence is:
•
•
When the security bit is active, the SECURITY bit in the MC_FSR is set.
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.
When the bit is set, 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.
Programming Error: A bad keyword and/or an invalid command have been written in the
MC_FCR register
If the general-purpose bit number is greater than the total number of general-purpose bits,
then the command has no effect.
Start the Clear General-purpose Bit command (CGPB) by writing the Flash Command
Register with CGPB and the number of the general-purpose bit to be cleared in the
PAGEN field.
When the clear 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.
Programming Error: a bad keyword and/or an invalid command have been written in the
MC_FCR register
If the number of the general-purpose bit set in the PAGEN field is greater than the total
number of general-purpose bits, then the command has no effect.
Start the Set Security Bit command (SSB) by writing the Flash Command Register.
When the 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.
Access to the Flash in read mode is permitted when a Set, Clear or Get General-purpose
NVM Bit command is performed.
AT91SAM7S32 Preliminary
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