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CHAPTER 4 SETTING METHODS
Note 2.
If the high-speed internal oscillation clock or an external clock input is selected as the system clock,
no oscillation stabilization time is required, so the setting becomes invalid (don’t care).
Caution Bits 4 and 7 must be set to 1.
Remark
x: don’t care
[Example 1]
The high-speed internal oscillation clock is used, used as the RESET pin, and the low-speed internal
oscillator can be stopped (same setting as the sample program).
Address: 0080H
Note
Stopping the low-speed internal oscillator oscillation, stopping watchdog timer operation, and setting the
clock frequency are performed after reset release. For details, refer to
The option byte setting value is “1
xx
1
11x0
(x: don’t care, bits 4 and 7 must be set to 1)”. When the software is
described together with the protect byte setting (hereinafter, writing to all blocks is enabled), the following results.
(“x” is set to 0 in the example below.)
To use C language, prepare an assembly language source file (file name: “*.asm (*: arbitrary)”) such as the one
shown below, specify it as the project source file, and build it together with other source files (main.c).
Remark
The protect byte (address: 0081H) is used to set the prohibited areas for writing and block erasure
whose set contents are valid only during self programming. For details, refer to the user’s manual of
each product (
,
).
OPBT CSEG
AT
0080H
DB
10011100B
DB
11111111B
OPBT CSEG
AT
0080H
DB
10011100B
DB
11111111B
end
1
x x
1
1 1 x 0
Control of low-speed internal oscillator oscillation
Note
0
Oscillation is stopped by software setting
(LSRSTOP bit is set to 1).
* In this sample program, the watchdog timer is not used.
Oscillation is therefore set so that it can be stopped by
software.
Selection of system clock source
Note
1
x High-speed internal oscillation clock (8 MHz (TYP.))
Selection of P34/RESET pin function
1
Used as a RESET pin.
Specification of oscillation stabilization time on power
application or after reset release
x x
(Crystal or ceramic oscillation is not used, so setting
is invalid.)
Application Note U18752EJ2V0AN
9