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Renesas Electronics America - Knowledgebase

Confirming the value of the option byte using a program (CC-RL)

Last Updated:06/14/2017


I am using the RL78 compiler CC-RL. How can the value of option byte be read while a MCU is operating?


The option byte area is the address that is not included in the mirror area of MCU (ROM).

Therefore, the far pointer should be used to access.

(For example) If you want to read the value of address 0C2h:

volatile unsigned char opdata;
opdata = (*(volatile __far unsigned char *)0x00c2);

Suitable Products
e² studio
CS+ (formerly CubeSuite+)
C Compiler Package for RL78 Family