Epson S1C63666 Technical Manual page 82

Cmos 4-bit single chip microcomputer

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CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Stopwatch Timer)

4.10.6 Interrupt function

10 Hz and 1 Hz interrupts

The 10 Hz and 1 Hz interrupts can be generated through the overflow of stopwatch timers SWD4–7

and SWD8–11 respectively. Also, software can set whether to separately mask the frequencies de-

scribed earlier.

Figure 4.10.6.1 is the timing chart for the counters.

Address

FF7AH

(1/1,000 sec BCD)

Address

FF7BH

(1/100 sec BCD)

10 Hz interrupt request

Address

FF7CH

(1/10 sec BCD)

1 Hz interrupt request

As shown in Figure 4.10.6.1, the interrupts are generated by the overflow of their respective counters ("9"

changing to "0"). Also, at this time the corresponding interrupt factor flag (ISW10, ISW1) is set to "1".

The respective interrupts can be masked separately through the interrupt mask registers (EISW10,

EISW1). However, regardless of the setting of the interrupt mask registers, the interrupt factor flags

are set to "1" by the overflow of their corresponding counters.

Fig. 4.10.6.1 Timing chart for counters

Stopwatch timer (SWD0–3) timing chart

Stopwatch timer (SWD4–7) timing chart

Stopwatch timer (SWD8–11) timing chart

EPSON

S1C63666 TECHNICAL MANUAL

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