PolyDaWG/8 for Low Cost Avnet FPGA Development Board

PolyDaWG/8 is an 8 voice polyphonic physical model synthesizer. It implements 8 Karplus-Strong string models in a harp that supports variable string length. String vibrational behavior is one dimensional due to RAM size limitations.

The source code provided here implements the PolyDaWG/8 synth on an inexpensive FPGA development board marketed by Avnet. This synth is functionally identical to the original version written for the Spartan-3E Starter Kit. The sound samples are from a Spartan-3E Starter Kit which has a 12 bit DAC. The Avnet board sounds essentially the same. Changes to the code for this version were made because of hardware differences between the boards, i.e., the Avnet board has no rotary encoder, no slide or DIP switches and no LCD display. There are 4 LEDs instead of 8. No changes were required to the core code which implements the digital waveguides.

This version runs at a sample rate of 200 KHz, that maximum for the DAC used, a Cirrus CS4344. The MIDI connection uses a 6N138 optoisolator, see docs subdirectory in the zip file for a schematic. With the addition of the DAC and the MIDI receiver, the synthesizer is fully self contained. It uses a modified version of the embedded PicoBlaze MIDI controller I wrote for the original S-3E version.

More Information and Sound Clips
Verilog Source