Pulse-Width Tone
7-52
7.7
Pulse-Width Tone
This pulse-width tone (PWT) module generates a modulated frequency signal
for the external buzzer. The frequency is programmable between 322 Hz and
4868 Hz with 12 half-tone frequencies per octave. The volume level is also pro-
grammable. All frequencies are generated from the PWT_CLK, which is a
12-MHz clock.
7.7.1
Overview
The PWT module creates the output tone signal for a buzzer. The frequency
and the volume of this signal are programmable.
7.7.2
PWT Features
The PWT module has the following features (see Figure 7–22):
-
Divider generating a 1500-kHz frequency clock
-
TIPB control interface
-
Four dividers with
101
/
107
,
49
/
55
,
50
/
63,
and
80
/
127
to generate each note
particularity
-
Four dividers 1/2 and a mux to select the octave
-
6-bit register to control tone frequency
-
6-bit register to control tone volume
-
2-bit register for testing and clk_en
-
5-bit counter and comparator for creating volume pulse
-
Divide by 1/154 to obtain the final right frequency
