Specifications

S1C6S2N7 TECHNICAL HARDWARE EPSON I-51

CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Stopwatch Timer)

The 10 Hz (approximate 10 Hz) and 1 Hz interrupts can be

generated by the overflow of the SWL and SWH stopwatch

timers, respectively. Also, software can separately mask the

frequencies as described earlier.

Figure 4.8.3 is the timing chart for the stopwatch timer.

Interrupt function

Fig. 4.8.3

Timing chart for

stopwatch timer

As shown in Figure 4.8.3, the interrupts are generated by

the overflow of the respective timers (9 changing to 0). Also

when this happens, the corresponding interrupt factor flags

(ISW0, ISW1) are set to 1. The respective interrupts can be

masked separately with the interrupt mask registers

(EISW0, EISW1). However, regardless of the setting of the

interrupt mask registers, the interrupt factor flags are set to

1 by the overflow of the corresponding timers.

Write to the interrupt mask registers (EISW0, EISW1) only in the DI

status (interrupt flag = 0). Otherwise, it may cause malfunction.

Note

Address

bits

Stopwatch timer (SWL) timing chart

Stopwatch timer (SWH) timing chart

Occurrence of

10 Hz interrupt request

Occurrence of

1 Hz interrupt request

0E3H

(1/10 sec BCD)

0E2H

(1/100 sec BCD)