ST10F273 Datasheet, PDF (39/179 Pages) STMicroelectronics – 16-bit MCU with 512 Kbyte Flash memory and 36 Kbyte RAM

ST10F273
Internal Flash memory
5.5.8
5.5.9
memory as listed in the first column, what is possible and what is not possible to do (see
column headers) is shown in the table.
Table 24. Summary of access protection level
Read IFlash /
jump to IFlash
Read XRAMS or
Ext Mem / Jump to
XRAM or Ext Mem
Fetching from IFlash
Yes / Yes
Yes / Yes
Fetching from IRAM
No / Yes
Yes / Yes
Fetching from XRAM
Fetching from External
memory
No / Yes
No / Yes
Yes / Yes
Yes / Yes
Read Flash
registers
Yes
Yes
Yes
Yes
Write Flash
registers
Yes
No
No
No
Write protection
The Flash modules have one level of Write Protections: Each sector of each bank can be
Software Write Protected by programming at 0 the related bit WyPx in FNVWPIRL/H
register.
Temporary unprotection
Bits WyPx of FNVWPIRL/H can be temporary unprotected by executing the Set Protection
operation and writing 1 into these bits.
Bit ACCP can be temporary unprotected by executing the Set Protection operation and
writing are executed from IFlash.
To restore the write access protection bits it is necessary to reset the microcontroller or to
execute a Set Protection operation and write 0 into desidered bits.
It is not necessary to temporary unprotect the access protected IFlash in order to update the
code: it is, in fact, sufficient to execute the updating instructions from another Flash bank.
In reality, when a temporary unprotection operation is executed, the corresponding volatile
register is written to 1, while the non volatile registers bits previously written to 0 (for a
protection set operation), will continue to mantain the 0. For this reason, the user software
must be in charge to track the current protection status (for instance using a specific RAM
area), it is not possible to deduce it by reading the non volatile register content (a temporary
unprotection cannot be detected).
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