HD64F3687HV Datasheet, PDF (286/538 Pages) Renesas Technology Corp – Renesas 16-Bit Single-Chip Microcomputer H8 Family/H8/300H Tiny Series

Section 14 Watchdog Timer
14.2.1 Timer Control/Status Register WD (TCSRWD)
TCSRWD performs the TCSRWD and TCWD write control. TCSRWD also controls the
watchdog timer operation and indicates the operating state. TCSRWD must be rewritten by using
the MOV instruction. The bit manipulation instruction cannot be used to change the setting value.
Initial
Bit
Bit Name Value R/W Description
7
B6WI
1
R/W Bit 6 Write Inhibit
The TCWE bit can be written only when the write value of
the B6WI bit is 0.
This bit is always read as 1.
6
TCWE 0
R/W Timer Counter WD Write Enable
TCWD can be written when the TCWE bit is set to 1.
When writing data to this bit, the value for bit 7 must be 0.
5
B4WI
1
R/W Bit 4 Write Inhibit
The TCSRWE bit can be written only when the write
value of the B4WI bit is 0. This bit is always read as 1.
4
TCSRWE 0
R/W Timer Control/Status Register WD Write Enable
The WDON and WRST bits can be written when the
TCSRWE bit is set to 1.
When writing data to this bit, the value for bit 5 must be 0.
3
B2WI
1
R/W Bit 2 Write Inhibit
This bit can be written to the WDON bit only when the
write value of the B2WI bit is 0.
This bit is always read as 1.
2
WDON 0
R/W Watchdog Timer On
TCWD starts counting up when WDON is set to 1 and
halts when WDON is cleared to 0.
[Setting condition]
When 1 is written to the WDON bit while writing 0 to the
B2WI bit when the TCSRWE bit=1
[Clearing conditions]
• Reset by RES pin
• When 0 is written to the WDON bit while writing 0 to
the B2WI when the TCSRWE bit=1
1
B0WI
1
R/W Bit 0 Write Inhibit
This bit can be written to the WRST bit only when the
write value of the B0WI bit is 0. This bit is always read as
1.
Rev.5.00 Nov. 02, 2005 Page 252 of 500
REJ09B0027-0500