UPD753012GC NEC, UPD753012GC Datasheet - Page 26

• Manufacturer Part Number: UPD753012GC
• Description: 4-BIT SINGLE-CHIP MICROCONTROLLER
• Manufacturer: NEC

6.6 Watch Timer
26
generator
The PD753017 has one channel of watch timer. The watch timer has the following functions.
• Sets the test flag (IRQW) with 0.5 sec interval.
• 0.5 sec interval can be created by both the main system clock and subsystem clock. Take f
• Convenient for program debugging and checking as interval becomes 128 times longer (3.91 ms) with the
• Outputs the frequencies (2.048, 4.096, 32.768 kHz) to the P23 and BUZ pins, usable for buzzer and trimming
• Clears the frequency divider to make the clock start with zero seconds.
From
clock
The standby mode can be released by the IRQW.
MHz for the main system clock frequency and f
fast feed mode.
of system clock frequencies.
(32.768 kHz)
f
(32.768 kHz)
128
XT
f
X
The values enclosed in parentheses are applied when f
WM
WM7
0
Selector
WM5
Figure 6-5. Watch Timer Block Diagram
f
(32.768 kHz)
W
WM4
8
WM3
Selector
4 kHz 2 kHz
Bit test instruction
WM2
2
f
W
3
XT
Internal bus
= 32.768 kHz for the subsystem clock.
2
f
WM1
W
4
Divider
WM0
Clear
X
= 4.194304 MHz and f
f
2
f
2
W
W
6
7
(512 Hz : 1.95 ms)
(256 Hz : 3.91 ms)
P23
output latch
PD753012, 753016, 753017
0.5 sec
2
PORT2.3
f
2 Hz
W
14
XT
Selector
= 32.768 kHz.
Port 2 input/
output mode
Output buffer
X
PMGB bit 2
= 4.194304
INTW
IRQW
set signal
f
LCD
P23/BUZ