NEC mPD784225 Series User Manual page 224

Figure 11-3. Operation Timing of Watch Timer/Interval Timer
Watch timer
Count clock
Watch timer
interrupt INTWT
Interval timer
interrupt INTTM3
Caution When enabling operation of the watch timer mode control register (WTM), watch timer, and 5-
bit counter, the time until the first watch timer interrupt request (INTWT) is generated is not
exactly the same time as set by bits 4 to 6 of WTM (WTM4 to WTM6). This is because the 5-bit
counter starts counting 1 cycle after 9-bit prescaler output. Following the first INTWT generation,
the INTWT signal is generated at the set interval time.
Remarks n: Number of interval timer operations
224
CHAPTER 11 WATCH TIMER
0H
Start
Interrupt time of watch timer
Interval time
(T)
nT
User's Manual U12697EJ3V0UM
Overflow
Interrupt time of watch timer
Interval time
(T)
nT
Overflow