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9 stopwatch timer, 1 configuration of stopwatch timer, 2 count-up pattern – Epson S1C63558 User Manual

Page 71

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S1C63558 TECHNICAL MANUAL

EPSON

61

CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Stopwatch Timer)

4.9 Stopwatch Timer

4.9.1 Configuration of stopwatch timer

The S1C63558 has 1/100 sec unit and 1/10 sec unit stopwatch timer built-in. The stopwatch timer is
configured with a 2 levels 4-bit BCD counter which has an input clock approximating 100 Hz signal
(signal divided from OSC1 to the closest 100 Hz) and data can be read in units of 4 bits by software.
Figure 4.9.1.1 shows the configuration of the stopwatch timer.

SWD0–3

Data bus

10 Hz, 1 Hz

256 Hz

10 Hz

Stopwatch timer reset signal

Divider

Interrupt
request

Interrupt

control

SWD4–7

Stopwatch timer RUN/STOP signal

Stopwatch timer

OSC1
oscillation circuit
(f

OSC1

)

Fig. 4.9.1.1 Configuration of stopwatch timer

The stopwatch timer can be used as a separate timer from the clock timer. In particular, digital watch
stopwatch functions can be realized easily with software.

4.9.2 Count-up pattern

The stopwatch timer is configured of 4-bit BCD counters SWD0–SWD3 and SWD4–SWD7.
The counter SWD0–SWD3, at the stage preceding the stopwatch timer, has an approximated 100 Hz
signal for the input clock. It counts up every 1/100 sec, and generates an approximated 10 Hz signal. The
counter SWD4–SWD7 has an approximated 10 Hz signal generated by the counter SWD0–SWD3 for the
input clock. In count-up every 1/10 sec, and generated 1 Hz signal.
Figure 4.9.2.1 shows the count-up pattern of the stopwatch timer.

26
256

26
256

26
256

26
256

26
256

26
256

25
256

25
256

25
256

25
256

3
256

2
256

3
256

2
256

2
256

2
256

3
256

3
256

3
256

2
256

3
256

2
256

3
256

3
256

3
256

3
256

3
256

2
256

2
256

2
256

26
256

25
256

26
256

25
256

x 6 +

x 4 = 1 (sec)

0 1 2 3 4 5 6 7 8 9 0

0 1 2 3 4 5 6 7 8 9 0

0 1 2 3 4 5 6 7 8 9 0

1 Hz
signal
generation

Approximate
10 Hz
signal
generation

Approximate
10 Hz
signal
generation

SWD4–7 count value

Counting time (sec)

(sec)

(sec)

SWD0–3 count value

Counting time (sec)

SWD0–3 count value

Counting time (sec)

SWD4–7 count-up pattern

SWD0–3 count-up pattern 1

SWD0–3 count-up pattern 2

Fig. 4.9.2.1 Count-up pattern of stopwatch timer