
5.2 Control
The watchdog timer is controlled by the watchdog timer control register (WDCTR), the watchdog timer control
code register (WDCDR), the watchdog timer counter monitor (WDCNT) and the watchdog timer status (WDST).
The watchdog timer is enabled automatically just after the warm-up operation that follows reset is finished.
Watchdog timer control register
WDCTR
(0x0FD4)
7
6
5
4
3
2
1
0
Bit Symbol
-
WDTEN
WDTW
WDTT
WDTOUT
Read/Write
R
R/W
After reset
1
0
1
0
1
0
WDTEN
Enables/disables the watchdog tim-
er operation.
0 :
1 :
Disable
Enable
WDTW
Sets the clear time of the 8-bit up
counter.
00 : The 8-bit up counter is cleared by writing the clear code at any point within
the overflow time of the 8-bit up counter.
01 : A watchdog timer interrupt request is generated by writing the clear code
at a point within the first quarter of the overflow time of the 8-bit up counter.
The 8-bit up counter is cleared by writing the clear code after the first quarter
of the overflow time has elapsed.
10 : A watchdog timer interrupt request is generated by writing the clear code
at a point within the first half of the overflow time of the 8-bit up counter.
The 8-bit up counter is cleared by writing the clear code after the first half
of the overflow time has elapsed.
11 : A watchdog timer interrupt request is generated by writing the clear code
at a point within the first three quarters of the overflow time of the 8-bit up
counter. The 8-bit up counter is cleared by writing the clear code after the
first three quarters of the overflow time have elapsed.
WDTT
Sets the overflow time of the 8-bit up
counter.
NORMAL mode
SLOW mode
DV9CK=0
DV9CK=1
00 :
218/fcgck
211/fs
01:
220/fcgck
213/fs
10:
222/fcgck
215/fs
11:
224/fcgck
217/fs
WDTOUT
Selects an overflow detection signal
of the 8-bit up counter.
0 :
1 :
Watchdog timer interrupt request signal
Watchdog timer reset request signal
Note 1: fcgck, Gear clock [Hz]; fs, Low frequency clock [Hz]
Note 2: WDCTR<WDTW>, WDCTR<WDTT> and WDCTR<WDTOUT> cannot be changed when WDCTR<WDTEN> is "1". If
WDCTR<WDTEN> is "1", clear WDCTR<WDTEN> to "0" and write the disable code (0xB1) into WDCDR to disable the
watchdog timer operation. Note that WDCTR<WDTW>, WDCTR<WDTT> and WDCTR<WDTOUT> can be changed at
the same time as setting WDCTR<WDTEN> to "1".
Note 3: Bit 7 and bit 6 of WDCTR are read as "1" and "0" respectively.
Watchdog timer control code register
WDCDR
(0x0FD5)
7
6
5
4
3
2
1
0
Bit Symbol
WDTCR2
Read/Write
W
After reset
0
WDTCR2
Writes watchdog timer control co-
des.
0x4E : Clears the watchdog timer. (Clear code)
0xB1 : Disables the watchdog timer operation and clears the 8-bit up counter
when WDCTR<WDTEN> is "0". (Disable code)
Others : Invalid
TMP89FH42
5. Watchdog Timer (WDT)
5.2 Control
Page 74
RA000