µPD750004, 750006, 750008, 750004(A), 750006(A), 750008(A)
6.5 BASIC INTERVAL TIMER/WATCHDOG TIMER
The basic interval timer/watchdog timer has these functions:
• Interval timer operation which generates a reference timer interrupt
• Operation as a watchdog timer for detecting program crashes and resetting the CPU
• Selection of wait time for releasing the standby mode and counting the wait time
• Reading out the count value
Fig. 6-4 Block Diagram of the Basic Interval Timer/Watchdog Timer
From the clock
generator
fX /25
fX /27
fX /29
fX /212
MPX
Clear signal
Basic interval timer
(8-bit frequency divider)
BT
Clear signal
Set
signal
BT interrupt
request flag
IRQBT
Vectored
interrupt
request
signal
3
BTM3 BTM2 BTM1 BTM0 BTM
SET1Note
4
8
Internal bus
Wait release
signal for standby
release
WDTM
1
SET1Note
Internal
reset signal
Note Instruction execution
25