I-130
EPSON
S1C88348/317/316/308 TECHNICAL HARDWARE
5 PERIPHERAL CIRCUITS AND THEIR OPERATION (Sound Generator)
5.13 Sound Generator
5.13.1 Configuration of sound generator
The S1C883xx has a built-in sound generator for
generating BZ (buzzer) signal.
BZ signals generated from the sound generator can
be output from the R50 output port terminal.
Aside permitting the respective setting of the
buzzer signal frequency and sound level (duty
adjustment) to 8 stages, it permits the adding of a
digital envelope by means of duty ratio control. It
also has a one-shot output function for outputting
key operated sounds.
Figure 5.13.1.1 shows the configuration of the
sound generator.
5.13.2 Control of buzzer output
BZ signal can be output from the R50 output port
terminal.
The configuration of the output port R50 is shown
in Figure 5.13.2.1.
The output control for the BZ signal generated by
the sound generator is done by the buzzer output
control register BZON, one-shot buzzer trigger bit
BZSHT and one-shot buzzer forced stop bit BZSTP.
When "1" is set to BZON or BZSHT, the BZ signal is
output from the R50 output port terminal and
when "0" is set to BZON or "1" is set to BZSTP, the
LOW (VSS) level is output. At this time, "0" must
always be set for the output data register R50D.
Figure 5.13.2.2 shows the output waveform of the
BZ signal.
Note: Since the BZ signal is generated asynchro-
nously from the registers BZON, BZSHT and
BZSTP, when the signal is turned ON or
OFF by the register settings, a hazard of a 1/
2 cycle or less is generated.
Fig. 5.13.1.1 Configuration of sound generator
Register BZSTP
Register BZON
Register BZSHT
R
SQ
One-shot time up
R50 output
BZ signal
Register R50D
Fig. 5.13.2.1 Configuration of R50
Fig. 5.13.2.2 Output waveform of BZ signal
BZON/BZSHT
BZ output (R50)
01
Dividing circuit
256 Hz
Envelope
addition circuit
Programmable
dividing circuit
BZFQ0–BZFQ2
DUTY0–DUTY2
Duty ratio
control circuit
ENRTM
BZON
ENON
ENRST
OSC1
oscillation circuit
fOSC1
BZSHT
One-shot buzzer
control circuit
SHTPW
BZSTP
Buzzer output
control circuit
Output port
R50
BZ (R50)