96
EPSON
S1C63656 TECHNICAL MANUAL
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Sound Generator)
4.12 Sound Generator
4.12.1 Configuration of sound generator
The S1C63656 has a built-in sound generator for generating a buzzer signal.
Hence, the generated buzzer signal can be output from the 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 4.12.1.1 shows the configuration of the sound generator.
f
OSC1
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. 4.12.1.1 Configuration of sound generator
4.12.2 Control of buzzer output
The BZ signal generated by the sound generator is output from the BZ terminal by setting "1" for the
buzzer output enable register BZE. When "0" is set to BZE register, the BZ terminal goes low (V
SS
).
BZE register
BZ output (BZ terminal)
"1"
"0"
"0"
Fig. 4.12.2.1 Buzzer signal output timing chart
Note: 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.