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10.7.2
Register Configuration
The WDT has the two registers summarized in table 10.5. These registers control clock selection
and timer mode switching.
Table 10.5 WDT Registers
Name
Watchdog timer
counter
Watchdog timer
control/status
register
Note: Use word-size access when writing. Perform the write with the upper byte set to H'5A or
H'A5, respectively. Byte- and longword-size writes cannot be used.
Use byte access when reading.
10.8
WDT Register Descriptions
10.8.1
Watchdog Timer Counter (WTCNT)
The watchdog timer counter (WTCNT) is an 8-bit readable/writable counter that counts up on the
selected clock. When WTCNT overflows, a reset is generated in watchdog timer mode, or an
interrupt in interval timer mode. WTCNT is initialized to H'00 only by a power-on reset via the
5(6(7 pin.
To write to the WTCNT counter, use a word-size access with the upper byte set to H'5A. To read
WTCNT, use a byte-size access.
Bit:
Initial value:
R/W:
Abbreviation
R/W
WTCNT
R/W*
WTCSR
R/W*
7
6
0
0
R/W
R/W
Initial
Value
P4 Address
H'00
H'FFC00008
H'00
H'FFC0000C
5
4
0
0
R/W
R/W
Area 7
Address
H'1FC00008
H'1FC0000C
3
2
0
0
R/W
R/W
Rev. 4.0, 04/00, page 209 of 850
Access Size
R: 8, W: 16*
R: 8, W: 16*
1
0
0
0
R/W
R/W
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