Audio DSP Project

  Overview

What inspired me to work on such a project since you can buy a new cheap Fx box everywhere ?

Of course, the market is full of effects processors in every price range. But sometimes I have a need for some very simple additional effects (such as delays) and some hard to find or not available (extraterrestrial) special effects ( time & amplitude quantization for "lo-fi"ing, ring modulation with any audio sources or adjustable harmonic generation - a "fine" digital version of distortion or exciting - wthout unwanted cross modulation)
 

  The Hardware

All you need to create your "personal" effects and to experiment with audio DSP is a common DSP evaluation kit - I preferred the Motorola EVM 56k for some advantages :
24 bit audio optimized processing and 66 Mhz power at an unbeatable price
2 analog inputs / 2 outputs + stereo headphone output, gain and amp control by software
relatively easy to learn assembler instructions similar to MC68k
the 56k is a common DSP for audio applications (Digidesign's TDM System, AudiomediaIII PCI audio board, Event Gina and many other audio boards and Fx devices)
You only need an extra EEPROM chip for program storage, put it in the free socket on the EVM board and you have a stand alone personal effects processor.
I built the DSP board in a 19" box ready for rack mount and added 2 LEDs (input level, signal and over) and 3 Switches (16 Positions each, 4 bit binary output).

  The Software

The Motorola Kit comes ready to connect to a pc (via serial cable) with Cross assembler and Loader / Debugger (full versions - you don't need any extra software) and original Manuals for the DSP...

But where the hell can I get some DSP programs to learn how to make my own effects ?

In the kit are some example programs (guided by manual) for a start up. Further examples you can get from Motorola and other Net sites -- Look at my   Links  !

Here's an example assembler program ready to add more effects (2 Ch. Line Delay and Time/Value Quantizer are working now):

efx03.zip     -    efx03.asm :  my personal F/x version 0.3 -- so don't expect too much
                        just assemble with the Motorola 56k Assembler (part of the EVM Board package)
THE PROGRAM IS PROVIDED TO YOU "AS IS", WITHOUT ANY WARRANTY. USE IT AT YOUR OWN RISK.