H838532H datasheet(162/508 Pages) RENESAS

162 / 508 page

Section 6 ROM

Rev. 1.00 May 30, 2008 Page 142 of 484

REJ09B0436-0100

6.6

Program/Erase Protection

There are three kinds of flash memory program/erase protection; hardware protection, software

protection, and error protection.

6.6.1

Hardware Protection

Hardware protection refers to a state in which programming/erasing of flash memory is forcibly

disabled or aborted because of a transition to reset, subactive mode, subsleep mode, watch mode,

or standby mode. Flash memory control register 1 (FLMCR1), flash memory control register 2

(FLMCR2), and erase block register (EBR) are initialized. In a reset via the

RES pin, the reset

state is not entered unless the

RES pin is held low until oscillation stabilizes after powering on. In

the case of a reset during operation, hold the

RES pin low for the RES pulse width specified in the

AC Characteristics section.

6.6.2

Software Protection

Software protection can be implemented against programming/erasing of all flash memory blocks

by clearing the SWE bit in FLMCR1. When software protection is in effect, setting the P or E bit

in FLMCR1 does not cause a transition to program mode or erase mode. By setting the erase block

protection is set for all blocks.

6.6.3

Error Protection

In error protection, an error is detected when CPU runaway occurs during flash memory

programming/erasing, or operation is not performed in accordance with the program/erase

algorithm, and the program/erase operation is aborted. Aborting the program/erase operation

prevents damage to the flash memory due to overprogramming or overerasing.

When the following errors are detected during programming/erasing of flash memory, the FLER

bit in FLMCR2 is set to 1, and the error protection state is entered.

• When the flash memory of the relevant address area is read during programming/erasing

(including vector read and instruction fetch)

• Immediately after exception handling excluding a reset during programming/erasing

• When a SLEEP instruction is executed during programming/erasing

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