User’s Manual U16899EJ2V0UD
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CHAPTER 24 OPTION BYTE
The 78K0/KE1+ has an area called an option byte at address 0080H of the flash memory. When using the
product, be sure to set the following functions by using the option byte.
{
Ring-OSC oscillation
•
Can be stopped by software.
•
Cannot be stopped.
Figure 24-1. Allocation of Option Byte
Option byte
0
0
Flash memory
0
0
0
0
RINGOSC
0 0 0 0 H
0 0 8 0 H
0
Figure 24-2. Format of Option Byte
Address: 0080H
7 6 5 4 3 2 1 0
0 0 0 0 0 0 0
RINGOSC
RINGOSC
Ring-OSC
oscillation
0
Can be stopped by software
1
Cannot
be
stopped
Cautions 1. To use the boot swap function, be sure to store the option data in the boot cluster 1 (for the
boot swap function, see 26.9 Boot Swap Function).
2. Be sure to clear bits 1 to 7 to 0.
Remark An example of software coding for setting the option bytes is shown below.
OPT
CSEG
AT
0080H
OPTION:
DB
03H
; Set to option byte (Ring-OSC cannot be stopped)