UPD75206CW NEC [NEC], UPD75206CW Datasheet - Page 17

• Manufacturer Part Number: UPD75206CW
• Description: 4-BIT SINGLE-CHIP MICROCOMPUTER
• Manufacturer: NEC [NEC]

5.4
From
Clock
Generator
The PD75206 incorporates one channel of watch timer. The watch timer has the following functions.
WATCH TIMER
Sets the test flag (IRQW) at 0.5 sec intervals.
The standby mode can be released by IRQW.
0.5 second interval can be set with the main system clock and subsystem clock.
The fast mode enables to set 128-time (3.91 ms) interval useful to program debugging and inspection.
The fixed frequencies (2.048 kHz) can be output to the P23/BUZ pin for use to generate buzzer sound
Since the frequency divider can be cleared, the watch can be started from zero second.
and trim the system clock oscillator frequency.
128
f
Remarks
(32.768 kHz)
(32.768 kHz)
f
XT
XX
WM
WM7 WM6 WM5 WM4
Values at f
Selector
XX
(32.768 kHz)
f
= 4.194304 MHz and f
W
Internal Bus
Fig. 5-3 Watch Timer Block Diagram
8
WM3
f
16
W
WM2 WM1 WM0
(2.048 kHz)
Frequency Divider
XT
= 32.768 kHz are indicated in parentheses.
Clear
2
f
W
7
(256 Hz : 3.91 ms)
P23
Output
Latch
PORT2.3
0.5 sec
f
2
W
2Hz
14
Selector
Port 2
Input/Output
Mode
Output Buffer
Bit 2 of PMGB
PD75206
INTW
IRQW
Set Signal
P23/BUZ
17