Renesas Hitachi H8S/2191, Hardware Manual

Page: 421 / 1065

Rev. 2.0, 11/00, page 394 of 1037
18.2 Register Descriptions
18.2.1 Watchdog Timer Counter (WTCNT)
7
0
R/W
6
0
R/W
5
0
R/W
4
0
R/W
3
0
R/W
0
0
R/W
2
0
R/W
1
0
R/W
Bit :
Initial value :
R/W :
TCNT is an 8-bit readable/writable* up-counter.
When the TME bit is set to 1 in WTCSR, WTCNT starts counting pulses generated from the
internal clock source selected by bits CKS2 to CKS0 in WTCSR. When the count overflows
(changes from H'FF to H'00), the OVF flag in WTCSR is set to 1.
WTCNT is initialized to H'00 by a reset, or when the TME bit is cleared to 0.
Note: * WTCNT is write-protected by a password to prevent accidental overwriting. For
details see section 18.2.4, Notes on Register Access.
18.2.2 Watchdog Timer Control/Status Register (WTCSR)
7
OVF
0
R/(W)
*
6
WT/IT
0
R/W
5
TME
0
R/W
4
RSTS
0
R/W
3
RST/NMI
0
R/W
0
CKS0
0
R/W
2
CKS2
0
R/W
1
CKS1
0
R/W
Note: * Only 0 can be written to clear the flag.
Bit :
Initial value :
R/W :
WTCSR is an 8-bit readable/writable* register. Its functions include selecting the clock source
to be input to WTCNT, and the timer mode.
WTCSR is initialized to H'00 by a reset.
Note: * WTCSR is write-protected by a password to prevent accidental overwriting. For
details see section 18.2.4, Notes on Register Access.