17 SOunD GeneRaTOR (SnD)
S1C17153 TeChniCal Manual
Seiko epson Corporation
17-3
(Rev. 1.0)
Buzzer Mode and Output Control
17.5
Buzzer Mode Selection
17.5.1
The SND module supports three buzzer modes that allow different types of buzzer outputs.
BZMD[1:0]/SND_CTL register is used to select a buzzer mode.
5.1.1 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 vol-
ume 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)
Output Control in normal Mode
17.5.2
In normal mode, setting BZEN/SND_CTL register to 1 starts buzzer output and setting it to 0 stops the output. The
buzzer frequency setting with BZFQ[2:0] and volume setting with BZDT[2:0] are both effective.
BZEN
BZ output
#BZ output
1
0
0
5.2.1 Buzzer Output in Normal Mode
Figure 17.
note
: The buzzer signal is generated asynchronously to BZEN, so a hazard may occur when the signal
is turned on or off by setting BZEN.
Output Control in One-shot Mode
17.5.3
The SND module has a one-shot output function for generating short buzzer sounds such as key operation sounds.
Output time selection
The one-shot buzzer output time can be selected from among four types shown below using BZTM[1:0]/SND_
CTL register.
5.3.1 One-shot Buzzer Output Time Selections
Table 17.
BZTM[1:0]
Output time
0x3
125 ms
0x2
62.5 ms
0x1
31.25 ms
0x0
15.63 ms
(Default: 0x0)
Output control
Writing 1 to BZEN/SND_CTL register starts one-shot buzzer output. When this trigger is issued, a buzzer sig-
nal is output from the buzzer output pin. When the set time 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.