Datasheet
Section 14 Watchdog Timer 
    Rev. 3.00 Sep. 10, 2007 Page 277 of 528 
   REJ09B0216-0300 
Bit Bit Name 
Initial 
Value 
R/W Description 
2 WDON 1  R/W Watchdog Timer On 
TCWD starts counting up when the WDON bit is set to 1 
and halts when the WDON bit is cleared to 0. The 
watchdog timer is enabled in the initial state. When the 
watchdog timer is not used, clear the WDON bit to 0. 
[Setting conditions] 
•  Reset 
•  When 1 is written to the WDON bit and 0 is written to 
the B2WI bit while the TCSRWE bit = 1 
[Clearing condition] 
•  When 0 is written to the WDON bit and 0 is written to 
the B2WI bit while 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. 
0 WRST 0  R/W Watchdog Timer Reset 
[Setting condition] 
•  When TCWD overflows and an internal reset signal is 
generated 
[Clearing conditions] 
•  Reset by the RES pin 
•  When 0 is written to the WRST bit and 0 is written to 
the B0WI bit while the TCSRWE bit = 1 










