Specifications

I-56 EPSON S1C62740 TECHNICAL HARDWARE
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Stopwatch Timer)
Stopwatch Timer4.9
Configuration of
stopwatch timer
The S1C62740 has a 1/100 sec and 1/10 sec stopwatch timer. The
stopwatch timer is configured of a two-stage, four-bit BCD counter
serving as the input clock of an approximately 100 Hz signal (signal
obtained by approximately demultiplying the 256 Hz signal output
by the oscillation circuit). Data can be read out four bits at a time
by the software.
Figure 4.9.1 is the block diagram of the stopwatch timer.
Fig. 4.9.1
Block diagram 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.
During data reading, a hold function the same as the clock timer
operates.
Refer to Section 4.8, "Clock Timer" for details of the hold function.
SWL counter
Data bus
10 Hz, 1 Hz
256 Hz
Stopwatch reset signal
OSC1
oscillation
circuit
Interrupt
request
SWH counter
10 Hz
Stopwatch RUN/STOP signal
Interrupt
control