15 SOunD GeneRaTOR
15-2
Seiko epson Corporation
S1C63003/004/008/016 TeChniCal Manual
(Rev. 1.1)
Buzzer Frequency and Sound level Settings
15.4
The divided signal of the OSC1 oscillation clock (32.768 kHz) is used for the buzzer signal and it is set up such that 8
types of frequencies can be selected by changing this division ratio. Frequency selection is done by setting the buzzer
frequency select register BZFQ[2:0] as shown in Table 15.4.1.
4.1 Buzzer signal frequency setting
Table 15.
BZFQ[2:0]
Buzzer frequency (Hz)
0
4096.0
1
3276.8
2
2730.7
3
2340.6
4
2048.0
5
1638.4
6
1365.3
7
1170.3
The buzzer sound level is changed by controlling the duty ratio of the buzzer signal.
The duty ratio can be selected from among the 8 types shown in Table 15.4.2 according to the setting of the buzzer
duty select register BDTY[2:0].
4.2 Duty ratio setting
Table 15.
Level
BDTY[2:0]
Duty ratio by buzzer frequency (Hz)
4096.0
3276.8
2730.7
2340.6
2048.0
1638.4
1365.3
1170.3
Level 1 (Max.)
0
8/16
8/20
12/24
12/28
Level 2
1
7/16
7/20
11/24
11/28
Level 3
2
6/16
6/20
10/24
10/28
Level 4
3
5/16
5/20
9/24
9/28
Level 5
4
4/16
4/20
8/24
8/28
Level 6
5
3/16
3/20
7/24
7/28
Level 7
6
2/16
2/20
6/24
6/28
Level 8 (Min.)
7
1/16
1/20
5/24
5/28
When the high level output time has been made TH and when the low level output time has been made TL due to the
ratio of the pulse width to the pulse synchronization, the duty ratio becomes TH/(TH+TL). When BDTY[2:0] has
been set to "0H," the duty ratio becomes maximum and the sound level also becomes maximum. Conversely, when
BDTY[2:0] has been set to "7H," the duty ratio becomes minimum and the sound level also becomes minimum. The
duty ratio that can be set is different depending on the frequency that has been set, so see Table 15.4.2.
Level 1 (Max.)
Level 2
Level 3
Level 4
Level 5
Level 6
Level 7
Level 8 (Min.)
TL TH
4.1 Duty ratio of the buzzer signal waveform
Figure 15.
Note: When a digital envelope has been added to the buzzer signal, the BDTY[2:0] settings will be invalid
due to the control of the duty ratio.