m37905 Renesas Electronics Corporation., m37905 Datasheet - Page 359

• Manufacturer Part Number: m37905
• Description: Mitsubishi 16-bit Single-chip Microcomputer 7700 Family / 7900 Series
• Manufacturer: Renesas Electronics Corporation.

WATCHDOG TIMER
14.1 Block description
The watchdog timer functions as follows:
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.
Fig. 14.1.1 Block diagram of watchdog timer
14-2
Watchdog timer clock source select
bits at STP termination
Detects a program runaway.
At stop mode termination, measures a certain time after oscillation starts. (Refer to section “15.3 Stop
mode.”)
Divided f(X
Wait mode
fX
fX
fX
fX
12 8
16
32
64
IN
f
)
Note: During the stop mode and until the stop mode is terminated, setting for disabling the
2
• Watchdog timer register: address 60
• Watchdog timer frequency select bit: bit 0 at address 61
• Watchdog timer clock source select bits at STP termination: bits 7, 6 at address 61
When the most significant bit of the watchdog timer becomes “0,” this signal will be generated.
watchdog timer is ignored. (Refer to section “14.1.3 Particular function select register 2.”)
1/ 16
Writing to watchdog
Disables watchdog
STP instruction
7905 Group User’s Manual Rev.1.0
timer register
timer (Note).
1/ 16
R ESET
Watchdog timer
frequency select bit
Wf
Wf
512
32
16
1
0
Stop mode
16
Watchdog timer
“FFF
16
” is set.
16
Watchdog timer
interrupt request