SM8521 datasheet(41/56 Pages) SHARP

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SM8521

- 41 -

SOUND GENERATOR

The SM8521 supports two waveform generators

concerning arbitrary waveform output channel and

one noise generator channel. After each channel's

signal is amplified through each variable register, a

digital mixer mixes them into one and D/A outputs it.

Address

generator

Scale

counter

Internal bus

Waveform generator

Waveform

memory

Digital

mixer

D/A

Sound output

D/A direct output channel

Noise sound generator

(Random rectangular waveform)

SG1

SG0

SG2

Fig. 19

Sound Generator Block Diagram

• Waveform generator

The data, 4-bit x 32 steps, stored in the waveform

(main clock) divided by time constant register.

• Digital mixer

4-bit data generated from each generator is

expanded to sixteen times as large as original 4-bit

data. Those expanded data is added to one

another after passing through digital attenuator (0,

1/32, 2/32, .... 31/32) of which attenuation rate is

specified by output level control register.

NOTE :

Attention to the sum total of each sound generator, not

exceeding capacity of digital mixer.

• Noise sound register

False noise, of which maximum frequency is based

on cycle divided FCK (main clock) by time constant

• D/A direct output register (in digital mixer)

When all sound generator 0, 1 and 2 are disable,

the data stored in this register is directly effective

as D/A input, provided that the data is stored in the

SGDA register and both sound output enable

set.

NOTE :

All 12 bits of each SG0, SG1 and SG2 must not be filled

with 0. If all 12 bits become 0, D/A can not perform correct

output.

SM8521 Datasheet(PDF) 41 Page - Sharp Corporation

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