S1C63808 TECHNICAL MANUAL
EPSON
97
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Sound Generator)
4.11 Sound Generator
4.11.1 Configuration of sound generator
The S1C63808 has a built-in sound generator for generating a buzzer signal.
Hence, the generated buzzer signal can be output from the R01 (BZ) terminal.
Aside permitting the respective setting of the buzzer signal frequency and sound level 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 4.11.1.1 shows the configuration of the sound generator.
fOSC1
R01 (BZ) terminal
Programmable
dividing circuit
256 Hz
One-shot buzzer
control circuit
Duty ratio
control circuit
BZFQ0–BZFQ2
BDTY0–BDTY2
Buzzer output
control circuit
Envelope
addition circuit
ENON
BZE
ENRTM
ENRST
BZSTP
BZSHT
SHTPW
Fig. 4.11.1.1 Configuration of sound generator
Note: If the BZ terminal is used to drive an external component that consumes a large amount of current
such as a bipolar transistor, design the pattern of traces on the printed circuit board so that the
operation of the external component does not affect the IC power supply. Refer to <Output Termi-
nals> in Section 5.3, "Precautions on Mounting", for more information.
4.11.2 Control of buzzer output
The BZ signal generated by the sound generator is output from the R01 (BZ) terminal by setting "1" for
the buzzer output enable register BZE. When "0" is set to BZE register, the R01 (BZ) terminal goes low
(VSS).
R01HIZ register
R01 register
BZE register
BZ output
Fix at "0"
Fix at "1"
"1"
"0"
Fig. 4.11.2.1 Buzzer signal output timing chart
Notes: When using the R01 port as the BZ output port, fix the data register R01 at "1" and the high
impedance control register R01HIZ at "0" (data output).
Since it generates the buzzer signal that is out of synchronization with the BZE register, hazards
may at times be produced when the signal goes on/off due to the setting of the BZE register.