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Chapter 9
Clock Generator
Preliminary User’s Manual U15839EE1V0UM00
9.3.3 Watchdog Timer Clock Control Register (WCC)
This is an 8-bit register that controls the watchdog timer clock. Data can be written to it only in a
sequence of specific instructions so that its contents are not easily rewritten in case of program
hang-up. See also PHCMD register.
This register can be read or written in 8-bit units.
Figure 9-4:
Watchdog Timer Clock Control Register (WCC)
Caution:
Data is set to the registers by the following sequence:
•
Write the set data to the command register (PHCMD) (see Chapter 3.6.2
“Peripheral Command Register (PHCMD)” on page 105).
•
Write the set data to the destination register (WCC)
Remarks: 1. If it is required to switch to another WDT clock source, it is recommended to monitor the
status of the concerned clock source to be selected before. Switching to an unstable
clock source is not protected by hardware.
2. The WCC register should be programmed immediately after occurrence of a system
Reset, even in the case that the default settings are intended to be used.
3. It is possible to change the contents of the WCC register only for one time after the
occurrence of a Reset.
7
6
5
4
3
2
1
0
Address
Initial
value
WCC
0
0
0
0
0
0
WDTSEL1 WDTSEL0 FFFFF826H
00H
Bit Position
Bit Name
Function
1, 0
WDTSEL1,
WDTSEL0
Specifies the clock source for the Watchdog
WDTSEL1 WDTSEL0
Watchdog clock source
0
0
Main oscillator (f
X
)
0
1
Sub oscillator (f
XT
)
1
0
Main oscillator /128 (f
X
/128)
1
1
reserved
Summary of Contents for mPD703128
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