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BLOCK DIAGRAM
Main Volume
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Orlginal sound
Sample/
Hold Circuit
PF4,PF6,PF7
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BSHH
Dlgilal S[nal Processor
M8661131
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Breath Sensor block outputs voltage whlch conesponds to the strength of breath.
Uslng a built-ln ADC (Analog lo DigitalConverter),
the CPU digitizes the voltage levellrom Breath Sensor
and outputs the digitized data P0-P7 lo DAC (Digital to Analog Converter) 1.
On the other hand, CPU detects pressed keys and provides conesponding sound slgnal PC6.
The sound signal is amplified and liltered in VCA (Voltage Controlled Amplifier) and VCF (Voltage
Controlled Fllter) whose anplitude and cutoff frequency depend upon control voltage from DAC1.
DAC1 converts the digitlzed data P0-P7 into a voltage levelwhich becomes control.vg$ggflf VCA and
VCF. Thus, the gound ouput PC-6's volume and cutotf frequeLcJt_g19_-vadeilln
accoi&n-ce with the
slrength of the breath.
VCF outprt ls digitized in DSP (D(;ital Signal Processor) and stored in the HAM.
Changing the reading speed ol RAM dala, the sound data is delayed, DAC'd,llllered, ard mixed with the
orlginal sound in Mlxer.
CPU
pPD78C1lG
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