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23.7
Flash Security Feature
The Flash Security Controller provides possibilities to protect the content of the flash
memory from being read from external pins.
■ Flash Security Feature
One predefined address of the flash memory is assigned to the Flash Security Controller (MB90F462,
MB90F462A: FF0001
access to the flash memory is restricted. Once the flash memory is protected, preforming the chip erase
operation only can unlock the function otherwise read/write access to the flash memory from any external
pins is not generally possible.
This function is suitable for applications requiring security of self-containing program and data stored in
the flash memory. If the target application requires any part of the program to locate outside the
microcontroller, the Flash Security Controller can not offer the intended features. For this reason, the
External Vector Fetch mode should not be used when the protection code is set.
Programming of the flash microcontroller by standard parallel programmer may require unique set-up. For
example, with the programmer from Minato Electronics the device checking should be turned off. Writing
the protection code is generally recommended to take place at the end of the flash programming. This is to
avoid unnecessary protection during the programming.
In order to re-program the once protected flash memory, the chip erase operation should be preformed.
For further information, please contact Fujitsu.
; MB90F463A: FE0001
H
H
CHAPTER 23 512K / 1024K BIT FLASH MEMORY
). If the protection code of "01
" is written in this address,
H
609
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