17 SOunD GeneRaTOR (SnD)
17-2
Seiko epson Corporation
S1C17153 TeChniCal Manual
(Rev. 1.0)
Buzzer Frequency and Volume Settings
17.4
Buzzer Frequency
17.4.1
The SND module generates the buzzer signal by dividing the OSC1A clock (32.768 kHz). The buzzer frequency
can be selected from among the eight types with different division ratios. BZFQ[2:0]/SND_BZFQ is used for this
selection.
4.1.1 Buzzer Frequency Selections
Table 17.
BZFQ[2:0]
Buzzer frequency (hz)
0x7
1170.3
0x6
1365.3
0x5
1638.4
0x4
2048.0
0x3
2340.6
0x2
2730.7
0x1
3276.8
0x0
4096.0
(Default: 0x0)
Volume level
17.4.2
The buzzer volume level is controlled by changing the duty ratio of the buzzer signal.
The volume level can be selected from among eight types using BZDT[2:0]/SND_BZDT register.
4.2.1 Volume Level Settings
Table 17.
Volume level
BZDT[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.)
0x0
8/16
8/20
12/24
12/28
Level 2
0x1
7/16
7/20
11/24
11/28
Level 3
0x2
6/16
6/20
10/24
10/28
Level 4
0x3
5/16
5/20
9/24
9/28
Level 5
0x4
4/16
4/20
8/24
8/28
Level 6
0x5
3/16
3/20
7/24
7/28
Level 7
0x6
2/16
2/20
6/24
6/28
Level 8 (Min.)
0x7
1/16
1/20
5/24
5/28
(Default: 0x0)
Setting BZDT[2:0] to 0x0 turns the volume up to maximum level; setting it to 0x7 turns the volume down to mini-
mum level.
Level 1 (Max.)
Level 2
Level 3
Level 4
Level 5
Level 6
Level 7
Level 8 (Min.)
H
Duty ratio = ————
Cycle
H
Cycle
4.2.1 Buzzer Signal Waveforms by Different Duty Ratios
Figure 17.
note
: BZDT[2:0] is ineffective in envelope mode, as the duty ratio is automatically controlled by the
hardware.
