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ADSP21161 EZ-KIT Lite Assembly based Talk-through

Analog Devices, Inc.
DSP Division
Three Technology Way
P.O. Box 9106
Norwood, MA 02062

Date Created:	8/16/01

This example provides a skeleton to build other audio examples off of.  It 
is simply a driver for the AD1836 which takes samples into one buffer and then
copies them over into another buffer to be output.  While running, the board
will simply pass-through the sound: converting A/D and then back D/A.
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CONTENTS

I.	FUNCTION/ALGORITHM DESCRIPTION
II.	IMPLEMENTATION DESCRIPTION
III.	OPERATION DESCRIPTION       


I. FUNCTION/ALGORITHM DESCRIPTION

There is no processing of the audio in this routine. 


II.   IMPLEMENTATION DESCRIPTION

When a serial port recieve interrupt occurs, the Process_Audio routine is called 
which imports and exports a sample.  The recieve data routine takes the 
left-justified fixed-point input-sample and converts it to 1.31 format floating point.
The reverse happens in the transmit routine.

In the proccess samples routine, between the recieve and transmit routines one
can insert a call to another algorithm to process the data, such as a filter or
a delay.  Many of the other audio routines accompanying the kit feature this
talkthrough as the backbone of the project.

More detailed comments can be found in the source code.


III.  OPERATION DESCRIPTION

- Plug in speakers to Ch 2 (Line Out)on the 21161 Ezkit Lite
- Plug in an audio source (mic or line)
- From the "Project" menu, select "Build Project".
- Open a ADSP21161 EZ-KIT Lite session in the VisualDSP++ Debugger.
- Load "AD1836_TALKTHRU.DXE"
- Run the Project and speak into the microphone and hear the sound on the speakers effect.
