IZ8057
FUNCTIONAL DESCRIPTION
Oscillator Circuit
The oscillation frequency is used as a time base for tone and tempo generators, the accuracy
of which affects the quality of which
affects the quality of the melody generator.
Tempo Generator
There are 14 tempos available in this embodiment: 82, 88, 95, 103, 112, 123, 137, 154, 176,
205, 246, 308, 410 and 615 notes per minute.
Tone Generator
The tone generator is a programmed divider. The tone frequencies are created by dividing
the oscillator frequencies with M,
where M is an integer from 32 to 127. There are 27 tones selectable in this embodiment,
including end code.
Rhythm Generator
The rhythm generator is also a programmed divider and is used to generate the beat for each
tone. In this embodiment, 15 beats
are available as follows: 1/4, 1/2, 3/4, 1, 5/4, 3/2, 7/4, 2, 9/4, 5/2, 11/4, 13/4, 7/2 and 15/4.
ROM
The mask ROM stores the tempo, tone and rhythm data. The ROM sends these data to
respective generators so as to control
the tempo of each song, the tone codes and the rhythm codes.
LED Blinking
The blinking of the light emitting diode (LED) is matched with rhythm of the melody.
Envelope Circuit
The envelope circuit made the melody and accompanement output MTO decreases
exponentially.
Pre-Amplifier
The Pre-Amplifier together with external P-N-P and N-P-N transistors works as audio-
amplifier. In application modulated tone
signal MTO should be connect to the input MI1 of the pre-amplifier through capacitor.
Feedback resistor must be connected to
obtain the proper bias for the pre-amplifier stage. In the standby state the pre-amplifier is
disabled, and OP1 is pulled up to VSS ;
OP2 is pulled down to VCC.
The Output Buffer
The Output Buffer amplifies signal from input MI2 and establishes two output signals BD, BDN
for directly drive piezo buzzer.
Korzhenevskogo 12, Minsk, 220064, Republic of
Belarus
Fax: +375 (17) 278 28 22,
Phone: +375 (17) 278 07 11, 277 24 70, 277 24 61,
277 69 16
E-mail: belms@belms.belpak.minsk.by
URL: www.bms.by
