Epson S1C63558 4.12 Sound Generator, 4.12.1 Configuration of sound generator, 4.12.2 Buzzer output circuit

CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Sound Generator)

4.12 Sound Generator

4.12.1 Configuration of sound generator

The S1C63558 has a built-in sound generator for generating buzzer signals. Hence, generated buzzer signals can be output from the R00 (XBZ) and R01 (BZ) terminals. 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.

		BZFQ0–BZFQ2	BDTY0–BDTY2		ENON
fOSC1		Programmable	Duty ratio		Envelope		ENRST
		dividing circuit	control circuit	addition circuit
							ENRTM			R00 (XBZ)
256 Hz		One-shot buzzer		Buzzer output				R00, R01
		control circuit		control circuit				output circuit		R01 (BZ)
	BZSHT
					BZE	BZOUT			XBZOUT
	BZSTP
	SHTPW

Fig. 4.12.1.1 Configuration of sound generator

4.12.2 Buzzer output circuit

The S1C63558 uses the R01 (BZ) and R00 (XBZ) terminals for outputting buzzer signals. To drive a piezoelectric buzzer with one terminal, use the BZ signal output from the R01 (BZ) terminal. The piezoelectric buzzer should be driven via a bipolar transistor. Since the R01 (BZ) terminal goes High level when the buzzer signal is stopped, use a PNP transistor as shown in Figure 4.12.2.1.

VDD VDD

R01 (BZ)

VSS

Fig. 4.12.2.1 Buzzer output circuit using the R01 (BZ) terminal

The S1C63558 allows direct driving of a piezoelectric buzzer using both the R01 (BZ) and R00 (XBZ) terminals. In this case, a piezoelectric buzzer should be connected to these terminals via protection resistors (100 Ω ) as shown in Figure 4.12.2.2.

R01 (BZ)

R00 (XBZ)

Fig. 4.12.2.2 Direct driving a piezoelectric buzzer using the R01 (BZ) and R00 (XBZ) terminals

100 EPSON S1C63558 TECHNICAL MANUAL