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17 SOunD GeneRaTOR (SnD)
17-6
Seiko epson Corporation
S1C17153 TeChniCal Manual
(Rev. 1.0)
D[5:4]
BZTM[1:0]: Buzzer envelope Time/One-shot Output Time Select Bits
Selects an envelope attenuation time or a one-shot output time.
6.2 Envelope Attenuation Time/One-shot Buzzer Output Time Selections
Table 17.
BZTM[1:0]
attenuation time/One-shot output time
0x3
125 ms
0x2
62.5 ms
0x1
31.25 ms
0x0
15.63 ms
(Default: 0x0)
In envelope mode, an attenuation time (time to change the duty ratio) can be selected (see Figure
17.5.4.1).
In one-shot mode, a one-shot buzzer output time can be selected (see Figure 17.5.3.1).
BZTM[1:0] does not affect buzzer outputs in normal mode.
D[3:2]
BZMD[1:0]: Buzzer Mode Select Bits
Selects a buzzer mode.
6.3 Buzzer Mode
Table 17.
BZMD[1:0]
Buzzer mode
0x3
Reserved
0x2
Envelope mode
A software trigger starts buzzer output. The SND module automatically turns down the
volume from Level 1 (maximum) and stops output when the volume reaches Level 8
(minimum).
0x1
One-shot mode
This mode is provided for generating short buzzer sounds such as key operation sounds.
The buzzer output starts by a software trigger and stops automatically after the specified
time has elapsed.
0x0
Normal mode
Buzzer output is turned on and off via software.
(Default: 0x0)
D1
Reserved
D0
BZen: Buzzer Output Control Bit
Controls buzzer output.
1 (R/W): On/Trigger
0 (R/W): Off (default)
Normal mode
Setting BZEN to 1 starts buzzer output and setting it to 0 stops the output.
One-shot mode
Writing 1 to BZEN starts one-shot buzzer output. When the time set with BZTM[1:0] has elapsed,
the buzzer output stops. BZEN functions as a status bit. It retains 1 while a one-shot buzzer signal
is being output and reverts to 0 upon completion of the output. Writing 0 to BZEN while a one-shot
buzzer signal is being output stops the output immediately. Writing 1 to BZEN again before a one-
shot buzzer output is finished, a new one-shot output begins from that point.
Envelope mode
Writing 1 to BZEN starts buzzer output in envelope mode. The duty ratio is set to Level 1 (maximum)
at the beginning of the output and is stepped down every attenuation time selected. When attenuated
down to Level 8 (minimum), the buzzer output stops. BZEN functions as a status bit. It retains 1
while a buzzer signal is being output and reverts to 0 upon completion of the output. Writing 0 to
BZEN while a buzzer signal is being output stops the output immediately. Writing 1 to BZEN again
before a buzzer output is finished, the duty ratio returns to the maximum level and a new envelope
output begins from that point.