R8CSLASH2G datasheet(279/344 Pages) RENESAS

279 / 344 page

R8C/2G Group

20. Flash Memory

Rev.1.00

Apr 04, 2008

Page 259 of 318

REJ09B0387-0100

• 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. When the FMR16 bit is set to 1 (rewrite disabled),

block erase commands targeting block 1 are not acknowledged.

In EW0 mode, the MCU enters read status register mode at the same time auto-erasure starts and the status

command is written.

Figure 20.11 shows the Block Erase Command in EW0 Mode.

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 20.11

Block Erase Command in EW0 Mode

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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