Z89340 datasheet(18/30 Pages) ZILOG

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Z89340

Digital Wavetable Engine

1-18

P R E L I M I N A R Y

DS96DSP0201

FUNCTIONAL DESCRIPTION (Continued)

Tape Loop Oscillator

The Tape Loop Oscillator takes its input from an input reg-

ister, an effects channel, or a submix register. It then reads

a sample from wave RAM, and writes the scaled input val-

ue plus the scaled and filtered sample from wave RAM

back to the same location in wave RAM. It behaves very

much like a tape recorder with a loop of tape, hence the

name “Tape Loop.” Echo and single-delay reverberation

can be accomplished with the Tape Loop Oscillator. The

amount of delay is set with the Wave Loop Length regis-

ters, and can be more than a second if you are willing to

dedicate the necessary RAM. This oscillator can also be

used to transfer input from a ADC that is connected to one

of the input registers. In this way the input can be buffered

in RAM for later use by the CPU host, or processing can

be done by the Z89340 before sending the signal to a ste-

reo submix register pair or one or more output channels.

The Tape Loop Oscillator can also perform the function of

the comb filter component of reverb algorithms (Figure

12).

Figure 12. The Tape Loop Oscillator Address Map

Z89340 数据表(PDF) 18 Page - Zilog, Inc.