HD64F36022 datasheet(117/384 Pages) RENESAS

117 / 384 page

Section 7 ROM

Rev. 4.00 Sep. 23, 2005 Page 91 of 354

REJ09B0025-0400

7.5

Program/Erase Protection

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

protection, and error protection.

7.5.1

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, subsleep mode or standby mode. Flash

memory control register 1 (FLMCR1), flash memory control register 2 (FLMCR2), and erase

block register 1 (EBR1) 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.

7.5.2

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

erase protection is set for all blocks.

7.5.3

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

HD64F36022 Datasheet(PDF) 117 Page - Renesas Technology Corp