Download Epson S5U1C63000H2 Specifications

CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Stopwatch Timer)
4.9 Stopwatch Timer
4.9.1 Configuration of stopwatch timer
The S1C6P466 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.
Data bus
Stopwatch timer
OSC1
oscillation circuit
(fOSC1)
Divider
256 Hz
10 Hz
SWD0–3
SWD4–7
10 Hz, 1 Hz
Stopwatch timer reset signal
Stopwatch timer RUN/STOP signal
Interrupt
control
Interrupt
request
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.
SWD4–7 count-up pattern
SWD4–7 count value
Counting time (sec)
0
1
2
3
4
5
6
7
8
9
0
26 26
25 25 26
26 25 25 26 26
256 256 256 256 256 256 256 256 256 256
1 Hz
signal
generation
26 x 6 + 25 x 4 = 1 (sec)
256
256
SWD0–3 count-up pattern 1
SWD0–3 count value
Counting time (sec)
0
1
3
256
2
3
4
5
6
7
8
9
0
2
3
2
3
2
3
2
3
2
256 256 256 256 256 256 256 256 256
25
256 (sec)
Approximate
10 Hz
signal
generation
SWD0–3 count-up pattern 2
SWD0–3 count value
Counting time (sec)
0
1
2
3
4
5
6
7
8
9
0
3
3
3
2
3
2
3
2
3
2
256 256 256 256 256 256 256 256 256 256
26 (sec)
256
Approximate
10 Hz
signal
generation
Fig. 4.9.2.1 Count-up pattern of stopwatch timer
S1C6P466 TECHNICAL MANUAL
EPSON
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