[sdiy] PolyDaWG/8 Updated

[Scott Gravenhorst]

http://www.fpga.synth.net/pmwiki/pmwiki.php?n=FPGASynth.DigitalWaveguide

ver_n.  This design is tunable and has one additional note in it's range. 
I've converted the design to use distributed RAM wherever possible and
speeded up both the filter and harp state machines.  I've also replaced
most of the primitive instantiations with verilog code that infers
correctly.  Only a few flipflops remain as primitives (RS types) so the
design should port more easily to environments other than my own.  The only
thing with which I am not happy is the tuning granularity, but it seems
usable and the synth is close enough to concert pitch at power up.  Tuning
was accomplished by adding a configurable number of additional clocks
between DAC enable pulses thus changing the sample rate.  There is no sonic
difference in this version, but it should compile and generate a bit file
in WebPACK ISE 9.2i (ver_l did not).

-- ScottG

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-- Scott Gravenhorst
-- GateMan II - Xilinx Spartan-3E Based MIDI Synthesizer with SVF
-- PolyDaWG/8 - 8 Voice FPGA Polyphonic MIDI Synthesizer
-- FatMan: home1.gte.net/res0658s/fatman/
-- NonFatMan: home1.gte.net/res0658s/electronics/
-- When the going gets tough, the tough use the command line.