UPD78F0078GK-9ET-A Renesas Electronics America, UPD78F0078GK-9ET-A Datasheet - Page 216

• Manufacturer Part Number: UPD78F0078GK-9ET-A
• Manufacturer: Renesas Electronics America

Specifications of UPD78F0078GK-9ET-A

• Lead Free Status / Rohs Status: Supplier Unconfirmed

10.5 Cautions for Watch Timer
(by setting bits 0 (WTM0) and 1 (WTM1) of WTM to 1), the interval until the first interrupt request (INTWT) is generated
after the register is set does not exactly match the specification made with bit 3 (WTM3) of WTM. This is because
there is a delay of one 9-bit prescaler output cycle until the 5-bit counter starts counting. Subsequently, however,
the INTWT signal is generated at the specified intervals.
then generated every 0.5 seconds.
214
Remark f
When operation of the watch timer and 5-bit counter is enabled by the watch timer operation mode register (WTM)
It takes 0.515625 seconds for the first INTWT to be generated (2
Count clock
Watch timer
interrupt INTWT
Interval timer
interrupt INTWTI
n: The number of interval timer operations
W
Figure 10-4. Example of Generation of Watch Timer Interrupt Request (INTWT)
: Watch timer clock frequency (f
WTM0, WTM1
5-bit counter
INTWT
Figure 10-3. Operation Timing of Watch Timer/Interval Timer
Start
0H
Interval time
(When Interrupt Period = 0.5 s)
0.515625 s
Interrupt time of watch timer
CHAPTER 10 WATCH TIMER
(T)
User’s Manual U14260EJ4V0UD
(2
14
X
/f
/2
W
7
or 2
or f
n x T
5
/f
XT
W
)
sec.)
0.5 s
Overflow
9
Interrupt time of watch timer
1/32768 = 0.015625 s longer). INTWT is
0.5 s
T
(2
14
/f
W
or 2
n x T
5
/f
W
sec.)
Overflow