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CHAPTER 23 OPTION BYTE
User’s Manual U19678EJ1V1UD
951
23.4 Setting of Option Byte
The user option byte and on-chip debug option byte can be set using the RA78K0R or PM+ linker option, in
addition to describing to the source. When doing so, the contents set by using the linker option take precedence,
even if descriptions exist in the source, as mentioned below.
See the RA78K0R Assembler Package User’s Manual for how to set the linker option.
A software description example of the option byte setting is shown below.
OPT
CSEG
OPT_BYTE
DB
16H
;
Does not use interval interrupt of watchdog timer,
;
Enables watchdog timer operation,
;
Window open period of watchdog timer is 25%,
;
Overflow time of watchdog timer is 2
10/fIL,
;
Stops watchdog timer operation during HALT/STOP mode
DB
0FFH
;
Reserved area
DB
0FFH
;
Reserved area
DB
85H
;
Enables on-chip debug operation, does not erase flash memory
;
data when security ID authorization fails
When the boot swap function is used during self programming, 000C0H to 000C3H is switched to 010C0H to
010C3H. Describe to 010C0H to 010C3H, therefore, the same values as 000C0H to 000C3H as follows.
OPT2
CSEG
AT
010C0H
DB
16H
;
Does not use interval interrupt of watchdog timer,
;
Enables watchdog timer operation,
;
Window open period of watchdog timer is 25%,
;
Overflow time of watchdog timer is 2
10/fIL,
;
Stops watchdog timer operation during HALT/STOP mode
DB
0FFH
;
Reserved area
DB
0FFH
;
Reserved area
DB
85H
;
Enables on-chip debug operation, does not erase flash memory
;
data when security ID authorization fails
Caution To specify the option byte by using assembly language, use OPT_BYTE as the relocation attribute
name of the CSEG pseudo instruction. To specify the option byte to 010C0H to 010C3H in order
to use the boot swap function, use the relocation attribute AT to specify an absolute address.