UPD78F9418AGK-9EU Renesas Electronics America, UPD78F9418AGK-9EU Datasheet - Page 134

• Manufacturer Part Number: UPD78F9418AGK-9EU
• Manufacturer: Renesas Electronics America

Specifications of UPD78F9418AGK-9EU

• Lead Free Status / Rohs Status: Supplier Unconfirmed

8.4 Operation of Watch Timer
8.4.1 Operation as watch timer
interrupts at 0.5-second intervals.
starts counting. By setting them to 0, the 5-bit counter is cleared and the watch timer stops counting.
from 0 seconds. However, an error of up to 2
(INTWT) after a 0-second start, because the 9-bit prescaler is not cleared in this case.
8.4.2 Operation as interval timer
value.
132
Other than above
WTM6
The main system clock (4.19 MHz) or subsystem clock (32.768 kHz) is used as a watch timer that generates
By setting bits 0 and 1 (WTM0 and WTM1) of the watch timer mode control register (WTM) to 1, the watch timer
When the interval timer also operates at the same time by setting WTM1 to 0, only the watch timer can be started
The interval timer is used to repeatedly generate an interrupt request at the interval specified by a preset count
The interval time can be selected by bits 4 to 6 (WTM4 to WTM6) of the watch timer mode control register (WTM).
Remark
0
0
0
0
1
1
WTM5
0
0
1
1
0
0
f
f
f
X
XT
W
: Main system clock oscillation frequency
: Watch timer clock frequency
: Subsystem clock oscillation frequency
WTM4
0
1
0
1
0
1
2
2
2
2
2
2
Setting prohibited
4
5
6
7
8
9
1/f
1/f
1/f
1/f
1/f
1/f
W
W
W
W
W
W
Interval
Table 8-3. Interval Time of Interval Timer
CHAPTER 8 WATCH TIMER
User’s Manual U13952EJ3V1UD
9
409.6 s
819.2 s
1.64 ms
3.28 ms
6.55 ms
13.1 ms
1/f
W
f
Operation at
X
seconds may occur for the first overflow of the watch timer
= 5.0 MHz
489 s
978 s
1.96 ms
3.91 ms
7.82 ms
15.6 ms
f
X
Operation at
= 4.19 MHz
488 s
977 s
1.95 ms
3.91 ms
7.81 ms
15.6 ms
f
XT
Operation at
= 32.768 kHz