h8s-2138 Renesas Electronics Corporation., h8s-2138 Datasheet - Page 440

• Manufacturer Part Number: h8s-2138
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2100 Series
• Manufacturer: Renesas Electronics Corporation.

Section 14 Watchdog Timer (WDT)
14.5.5
To clear OVF flag in WOVI handling routine, read TCSR when OVF=1, then write with 0 to
OVF, as stated above. When WOVI is masked and OVF flag is poling, if contention between OVF
flag set and TCSR read is occurred, OVF=1 is read but OVF can not be cleared by writing with 0
to OVF.
In this case, reading TCSR when OVF=1 two times meet the requirements of OVF clear condition.
Please read TCSR when OVF=1 two times before writing with 0 to OVF.
Rev. 4.00 Jun 06, 2006 page 386 of 1004
REJ09B0301-0400
OVF Flag Clear Condition
LOOP
BTST.B
BEQ
MOV.B
MOV.W
MOV.W
#7,@TCSR
LOOP
@TCSR,R0L
#H’A521,R0
R0,@TCSR
; OVF flag read
; if OVF=1, exit from loop
; OVF=1 read again
; OVF flag clear
; :