R8C2K datasheet(405/471 Pages) RENESAS

405 / 471 page

R8C/2K Group, R8C/2L Group

20. Flash Memory

Rev.1.10

Dec 21, 2007

Page 388 of 450

REJ09B0406-0110

• Block Erase

When 20h is first written and then D0h is written to a given block address, an auto-erase operation (erase and

verify) of the specified block starts.

The FMR00 bit in the FMR0 register can be used to determine whether auto-erasure has completed.

The FMR00 bit is set to 0 during auto-erasure and set to 1 when auto-erasure completes.

The FMR07 bit in the FMR0 register can be used to determine the result of auto-erasure after auto-erasure has

completed (refer to 20.4.2 Status Check Procedure).

Also, when the FMR02 bit in the FMR0 register is set to 0 (rewrite disabled), or the FMR02 bit is set to 1

(rewrite enabled) and the FMR15 bit in the FMR1 register is set to 1 (rewrite disabled), block erase commands

targeting block 0 are not acknowledged.

Do not use the block erase command during program-suspend.

Do not execute this command for any address to which a rewrite control program is allocated.

Figure 20.21 shows the Block Erase Command in EW1 Mode (When Suspend Function Disabled). Figure

20.22 shows the Block Erase Command in EW1 Mode (When Suspend Function Enabled).

If the programming and erasure endurance is n (n = 100, 1000, or 10,000), each block can be erased n times.

For example, if 1,024 1-byte writes are performed to block A, a 1-Kbyte block, and then the block is erased,

the erase count stands at one. When performing 100 or more rewrites, the actual erase count can be reduced by

executing programming operations in such a way that all blank areas are used before performing an erase

operation. Avoid rewriting only particular blocks and try to average out the programming and erasure

endurance of the blocks.

It is also advisable to retain data on the erase count of each block and limit the number of erase operations to a

certain number.

Figure 20.21

Block Erase Command in EW1 Mode (When Suspend Function Disabled)

Start

Write the command code 20h

Write D0h to any block

address

FMR00 = 1?

Full status check

Block erase completed

Yes

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