RL78/G1H CHAPTER 27 FLASH MEMORY
R01UH0575EJ0120 Rev. 1.20 Page 823 of 920
Dec 22, 2016
27.6 Security Settings
The RL78 microcontroller supports a security function that prohibits rewriting the user program written to the internal
flash memory, so that the program cannot be changed by an unauthorized person.
The operations shown below can be performed using the Security Set command.
• Disabling block erase
Execution of the block erase command for a specific block in the flash memory is prohibited during serial
programming. However, blocks can be erased by means of self-programming.
• Disabling write
Execution of the write command for entire blocks in the flash memory is prohibited during serial programming.
However, blocks can be written by means of self-programming.
After the setting of prohibition of writing is specified, releasing the setting by the Security Release command is
enabled by a reset.
• Disabling rewriting boot cluster 0
Execution of the block erase command and write command on boot cluster 0 (00000H to 00FFFH) in the flash
memory is prohibited by this setting.
The block erase, write commands, and rewriting boot cluster 0 are enabled by the default setting when the flash
memory is shipped. Security can be set by serial programming and self-programming. Each security setting can be
used in combination.
Table 27 - 10 shows the relationship between the erase and write commands when the RL78 microcontroller security
function is enabled.
Caution The security function of the flash programmer does not support self-programming.
Remark To prohibit writing and erasing during self-programming, use the flash shield window function (see 27.5.3
for detail).
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