UPD78F0890GK(A)-GAJ-AX NEC, UPD78F0890GK(A)-GAJ-AX Datasheet - Page 269

• Manufacturer Part Number: UPD78F0890GK(A)-GAJ-AX
• Description: 8BIT MCU, 128K FLASH, 7K RAM, LQFP
• Manufacturer: NEC

Specifications of UPD78F0890GK(A)-GAJ-AX

• Controller Family/series: UPD78F
• No. Of I/o's: 55
• Ram Memory Size: 7KB
• Cpu Speed: 20MHz
• No. Of Timers: 10
• No. Of Pwm: RoHS Compliant
• Core Size: 8bit
• Program Memory Size: 128KB
• Oscillator Type: External, Internal

10.4 Watch Timer Operations
10.4.1 Watch timer operation
hardware clock or subsystem clock.
operation starts. When these bits are cleared to 0, the 5-bit counter is cleared and the count operation stops.
clearing WTM1 to 0. In this case, however, the 11-bit prescaler is not cleared. Therefore, an error up to 2
seconds occurs in the first overflow (INTWT) after zero-second start.
Remarks 1. f
WTM3
The watch timer generates an interrupt request signal (INTWT) at a specific time interval by using the peripheral
When bit 0 (WTM0) and bit 1 (WTM1) of the watch timer operation mode register (WTM) are set to 1, the count
When the interval timer is simultaneously operated, zero-second start can be achieved only for the watch timer by
The interrupt request is generated at the following time intervals.
0
0
1
1
WTM2
2. f
3. f
0
1
0
1
W
PRS
SUB
:
Interrupt Time
2
2
2
2
: Peripheral hardware clock frequency
: Subsystem clock frequency
14
13
5
4
/f
/f
Watch timer clock frequency (f
Selection
/f
/f
W
W
W
W
When Operated at
f
0.5 s
0.25 s
977
488
SUB
(WTM7 = 1)
= 32.768 kHz
μ
μ
s
s
Table 10-4. Watch Timer Interrupt Time
CHAPTER 10 WATCH TIMER
User’s Manual U17554EJ4V0UD
When Operated at
0.53 s
0.26 s
1.03 ms
0.51 ms
PRS
f
(WTM7 = 0)
PRS
/2
7
= 4 MHz
or f
SUB
)
When Operated at
0.419 s
0.210 s
819
410
f
(WTM7 = 0)
PRS
μ
μ
s
s
= 5 MHz
When Operated at
0.210 s
0.105 s
410
205
f
PRS
(WTM7 = 0)
μ
μ
s
s
= 10 MHz
When Operated at
0.105 s
52.5 ms
205
102
f
PRS
(WTM7 = 0)
μ
μ
= 20 MHz
s
s
9
× 1/f
269
W