Renesas rl78 User Manual

 

RL78/G1A 

CHAPTER  25   FLASH  MEMORY 

 

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 code 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. 

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•  Disabling rewriting boot cluster 0 

Execution of the block erase command and write command on boot cluster 0 (00000H to 00FFFH) in the code 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 25-12 shows the relationship between the erase and write commands when the RL78 microcontroller security 

function is enabled. 

 

Remark  To prohibit writing and erasing during self-programming, use the flash shield window function (see 25.6.3 for 

details). 

 

R01UH0305EJ0200  Rev.2.00 

 

 

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Jul 04, 2013