Epson S1C63558 4.12.6 One-shotoutput

CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Sound Generator)

4.12.6 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 BZ and XBZ terminals. 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 4.12.6.1 shows timing chart for one-shot output.

256 Hz
R01HIZ register	"0"
R00HIZ register	"0"
R01 register	"1"
R00 register	"1"
BZOUT register	"1"
XBZOUT register	"1"
BZE register	"0"
SHTPW register
BZSHT (W)
BZSHT (R)
BZSTP
R01(BZ) port
R00(XBZ) port

Fig. 4.12.6.1 Timing chart for one-shot output

104 EPSON S1C63558 TECHNICAL MANUAL