W681307 Datasheet, PDF (45/160 Pages) Winbond – USB1.1 CODEC Microprocessor Control Unit with 32KB Mask ROM and 4KB RAM

W681307
8.3
Ringer Tone Generator
8.3.1
Overview
The buzzer signal generates tones to signal an incoming call.
There are two buzzer signal can be selected to connect to SNDR pin. This subsection describes the Ringer Tone Generator with the PWM
(Pulse Width Modulation) format. The other buzzer signal of PDM (Pulse Density Modulation) format will be described on 1503[1:0].
8.3.2
Functionality
SounderTone1
SounderVol1
Sysclk
/16 /N ^864KHz
3388Hz to 864KHz
/32
Decoder ^{105Hz to 27KHz}
Sounder
Sysclk
/16 /N ^864KHz
3388Hz to 864KHz
/32
Decoder ^{105Hz to 27KHz}
SounderTone2
SounderVol2
Figure 8-3 The Ringer Tone Generator
The Ringer Tone Generator has two controllable tone sources, shown in Figure 8-3. This each gives a programmable output frequency of
between 105Hz and 27KHz. Each tone source has a programmable mark-to-space ratio. By controlling the mark to space ratio the volume
of the sounder can be controlled.
• The ÷16 function produces a 864kHz pulse from the 13.824MHz system clock.
• The ÷n function produces a 3388 to 864kHz pulse from its 864kHz input. The output frequency of this function and the
corresponding output frequency of the chip is determined by the SounderTone register.
• The ÷ 32 function contains a counter, clocked by the system clock, which increments on each pulse at it input. The Decoder
uses the 4-bit output from this counter to produce a 105Hz to 27kHz with a programmable Mark-Space ratio defined by the
SounderVol register.
• The tone source always starts in the same way (for a given set of programmed values)
• The tone source stops cleanly, that is it stops in the inactive state (logic 0) without truncation of any ongoing high pulse.
• The results of tone source one and tone source two are logically OR together to produce the output signal Sounder”.
• Both tone generators have a common enable signal to allow them to be synchronized together.
•
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Publication Release Date: May, 2007
Revision 1.3