Chapter 17 Option Byte; Functions Of Option Byte - NEC 78K0S/KA1+ User Manual

17.1 Functions of Option Byte

The address 0080H of the flash memory of the 78K0S/KA1+ is an option byte area. When power is supplied or
when starting after a reset, the option byte is automatically referenced, and settings for the specified functions are
performed. When using the product, be sure to set the following functions by using the option byte.
(1) Selection of system clock source
• High-speed internal oscillation clock
• Crystal/ceramic oscillation clock
• External clock input
(2) Low-speed internal oscillation clock oscillation
• Cannot be stopped.
• Can be stopped by software.
(3) Control of RESET pin
• Used as RESET pin
• RESET pin is used as an input port pin (P34).
(4) Oscillation stabilization time on power application or after reset release
10
• 2 /f
X
12
• 2
/f
X
15
• 2
/f
X
17
• 2 /f
X
07FFH/0FFFH
2048/4096
0080H
0000H

CHAPTER 17 OPTION BYTE

Figure 17-1. Positioning of Option Byte
Flash memory
×
8 bits)
User's Manual U16898EJ3V0UD
Option byte
DEF DEF
1 1
OSTS1 OSTS0
RMCE OSCSEL1 OSCSEL0 LIOCP
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