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EPSON
S1C63666 TECHNICAL MANUAL
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Sound Generator)
4.13.5 One-shot output
The sound generator has a one-shot output function for outputting a short duration buzzer signal for key
operation sounds and similar effects. Either 125 msec or 31.25 msec can be selected by SHTPW register
for one-shot buzzer signal output time.
The output of the one-shot buzzer is controlled by writing "1" into the one-shot buzzer trigger BZSHT.
When this trigger has been assigned, a buzzer signal in synchronization with the internal 256 Hz signal is
output from the buzzer output terminal. Thereafter, when the set time has elapsed, a buzzer signal in
synchronization with the 256 Hz signal goes off in the same manner as for the start of output.
The BZSHT also permits reading. When BZSHT is "1", the one-shot output circuit is in operation (during
one-shot output) and when it is "0", it shows that the circuit is in the ready (outputtable) status.
In addition, it can also terminate one-shot output prior to the elapsing of the set time. This is done by
writing a "1" into the one-shot buzzer stop BZSTP. In this case as well, the buzzer signal goes off in
synchronization with the 256 Hz signal.
When "1" is written to BZSHT again during a one-shot output, a new one-shot output for 125 msec or
31.25 msec starts from that point (in synchronization with the 256 Hz signal).
The one-shot output cannot add an envelope for short durations. However, the sound level can be set by
selecting the duty ratio, and the frequency can also be set.
One-shot output is invalid during normal buzzer output (during BZE = "1").
Figure 4.13.5.1 shows timing chart for one-shot output.
256 Hz
SHTPW
BZSHT (W)
BZSHT (R)
BZSTP
BZ output
BZ output
Fig. 4.13.5.1 Timing chart for one-shot output
