M32CSLASH86 datasheet(435/505 Pages) RENESAS

435 / 505 page

Page 412

25. Flash Memory Version

)

(

25.3.6 Data Protect Function

Each block in the flash memory has a nonvolatile lock bit. The lock bit is enabled by setting the FMR02 bit

to "0" (lock bit enabled). The lock bit individually protects (locks) each block against program and erase.

This prevents data from being inadvertently written to or erased from the flash memory.

• When the lock bit status is set to "0", the block is locked (block is protected against program and erase).

• When the lock bit status is set to "1", the block is not locked (block can be programmed or erased).

The lock bit status is set to "0" (locked) by executing the lock bit program command and to "1" (unlocked)

by erasing the block. The lock bit status cannot be set to "1" by any commands.

The lock bit status can be read by the read lock bit status command.

The lock bit function is disabled by setting the FMR02 bit to "1". All blocks are unlocked. However,

individual lock bit status remains unchanged. The lock bit function is enabled by setting the FMR02 bit to

"0". Lock bit status is retained.

If the block erase or erase all unlocked block command is executed while the FMR02 bit is set to "1", the

target block or all blocks are erased regardless of lock bit status. The lock bit status of each block are set

to "1" after an erase operation is completed.

Refer to 25.3.5 Software Commands for details on each command.

25.3.7 Status Register (SRD Register)

The SRD register indicates the flash memory operating state and whether or not an erase or program

operation is completed as expected. The FMR00, FMR06 and FMR07 bits in the FMR0 register indicate

SRD register states.

Table 25.5 shows the SRD register.

In EW mode 0, the SRD register can be read when the followings occur.

• Any even address in the user ROM area is read after writing the read status register command

• Any even address in the user ROM area is read from when the program, block erase, erase all

unlocked block, or lock bit program command is executed until when the read array command is

executed.

25.3.7.1 Sequencer Status (SR7 and FMR00 Bits )

The sequencer status indicates the flash memory operating state. It is set to "0" while the program,

block erase, erase all unlocked block, lock bit program, or read lock bit status command is being

executed; otherwise, it is set to "1".

25.3.7.2 Erase Status (SR5 and FMR07 Bits)

Refer to 25.3.8 Full Status Check.

25.3.7.3 Program Status (SR4 and FMR06 Bits)

Refer to 25.3.8 Full Status Check.

M32C/86 Datasheet(PDF) 435 Page - Renesas Technology Corp