WATCHDOG TIMER
14.1 Block description
The watchdog timer functions as follows:
ꢀ Detects a program runaway.
ꢀ At stop mode termination, measures a certain time after oscillation starts. (Refer to section “15.3 Stop
mode.”)
14.1 Block description
Figure 14.1.1 shows the block diagram of the watchdog timer, and registers relevant to the watchdog timer
are described below.
Watchdog timer
frequency select bit
Stop mode
1
f
2
Wf32
1/ 16
Wait mode
Watchdog timer
interrupt request
Wf512
1/ 16
Watchdog timer
0
ꢀ
Divided f(XIN
)
fX 16
fX 32
“FFF16” is set.
fX 64
fX 12 8
Disables watchdog
timer (Note).
Writing to watchdog
timer register
Watchdog timer clock source select
bits at STP termination
RESET
STP instruction
• Watchdog timer register: address 6016
• Watchdog timer frequency select bit: bit 0 at address 6116
• Watchdog timer clock source select bits at STP termination: bits 7, 6 at address 6116
ꢀ When the most significant bit of the watchdog timer becomes “0,” this signal will be generated.
Note: During the stop mode and until the stop mode is terminated, setting for disabling the
watchdog timer is ignored. (Refer to section “14.1.3 Particular function select register 2.”)
Fig. 14.1.1 Block diagram of watchdog timer
7906 Group User’s Manual Rev.2.0
14-2
RENESAS [ RENESAS TECHNOLOGY CORP ]
