NEC 78K0 Series User Manual page 572

26.8 Security Settings
The operations shown below can be performed using the security setting command. The security setting is valid
when the programming mode is set next.
• Disabling batch erase (chip erase)
Execution of the block erase and batch erase (chip erase) commands for entire blocks in the flash memory is
prohibited by this setting. Once execution of the batch erase (chip erase) command is prohibited, all of the
prohibition settings can no longer be cancelled.
Caution After the security setting for the batch erase is set, erasure cannot be performed for the device.
In addition, even if a write command is executed, data different from that which has already
been written to the flash memory cannot be written, because the erase command is disabled.
• Disabling block erase
Execution of the block erase command for a specific block in the flash memory is prohibited by this setting. This
prohibition setting can be cancelled using the batch erase (chip erase) command.
• Disabling write
Execution of the write and block erase commands for entire blocks in the flash memory is prohibited by this
setting. This prohibition setting can be cancelled using the batch erase (chip erase) command.
• Disabling rewriting boot cluster 0
Execution of the batch erase (chip erase) command, block erase command, and write command on boot cluster
0 (0000H to 0FFFH) in the flash memory is prohibited by this setting.
Caution If a security setting that rewrites boot cluster 0 has been applied, boot cluster 0 of that device
will not be rewritten.
The batch erase (chip erase), block erase, write commands, and rewriting boot cluster 0 are enabled by the default
setting when the flash memory is shipped. The above security settings are only possible for on-board/off-board
programming. Each security setting can be used in combination.
Table 26-10 shows the relationship between the erase and write commands when the 78K0/KE2 security function
is enabled.
Table 26-10. Relationship Between Commands When Security Function Is Enabled
Security Setting
Disabling batch erase (chip erase)
Disabling block erase
Disabling write
Disabling rewriting boot cluster 0
Note Since the erase command is disabled, data different from that which has already been written to the
flash memory cannot be written.
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CHAPTER 26 FLASH MEMORY
Command Batch Erase (Chip
Erase) Command
Invalid
Valid
Invalid
Preliminary User's Manual U17260EJ3V1UD
Block Erase Write Command
Command
Note
Invalid Valid
Valid
Invalid