17 SOunD GeneRaTOR (SnD)
S1C17153 TeChniCal Manual
Seiko epson Corporation
17-1
(Rev. 1.0)
Sound Generator (SND)
17
SnD Module Overview
17.1
The S1C17153 includes a sound generator (SND) for generating a buzzer signal.
The main features of the SND module are outlined below.
• Provides buzzer inverted and non-inverted output pins to directly drive a piezoelectric buzzer.
• Programmable buzzer signal frequency (eight frequencies) and volume level (eight levels)
• Duty ratio controlled digital envelope function (attenuation time is selectable from four types.)
• One-shot output function (output time is selectable from four types.)
Figure 17.1.1 shows the SND configuration.
BZ
#BZ
OSC1A
Gate
Programmable
divider
Duty ratio
control circuit
Envelope
addition circuit
One-shot buzzer
control circuit
Buzzer output
control circuit
SND
SNDCLKE
BZMD[1:0] BZTM[1:0]
BZEN
BZFQ[2:0]
BZDT[2:0]
1.1 SND Module Configuration
Figure 17.
SnD Output Pins
17.2
Table 17.2.1 lists the SND pins.
2.1 List of SND Pins
Table 17.
Pin name
i/O
Qty
Function
BZ
O
1
Buzzer non-inverted output pin
Outputs the buzzer signal generated by the sound generator.
#BZ
O
1
Buzzer inverted output pin
Outputs the inverted buzzer signal generated by the sound generator.
The SND module output pins (BZ, #BZ) are shared with I/O ports and are initially set as general purpose I/O port
pins. The pin functions must be switched using the port function select bits to use the general purpose I/O port pins
as SND module output pins. For detailed information on pin function switching, see the “I/O Ports (P)” chapter.
SnD Operating Clock
17.3
The SND module uses the OSC1A clock (32.768 kHz Typ.) output from the CLG as its operating clock.
The OSC1A clock supply to the SND module is enabled with SNDCLKE/SND_CLK register. The SNDCLKE
default setting is 0, which stops the clock. Setting SNDCLKE to 1 feeds the OSC1A clock to the SND module. Set
SNDCLKE to 1 before performing buzzer output. If no buzzer output is required, stop the clock to reduce current
consumption.
For more information on OSC1A oscillator control, see the “Clock Generator (CLG)” chapter.
note
: This chapter describes buzzer frequencies and one-shot output times assuming that the OSC1A
clock frequency is 32.768 kHz. The frequencies and times vary depending on the OSC1A clock
frequency.
