[sdiy] GateMan II Update

Scott Gravenhorst music.maker at gte.net
Sat Sep 22 18:33:40 CEST 2007


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

I got motivated after hearing the state variable filter, so I added
oscillator synch and improved the ADSR code for both ADSRs.  Small
modifications to the MIDI controller were also applied due to new demands
made by synch.  The PicoBlaze assembly code uses just slightly more than
1/2 the allocated ROM, so there's still room.

Turning synch on and using rather long portamento causes timbre evolution
as notes are changed, greater distances between notes causing a more
profound evolution.   Low bandwidth noise modulation is also interesting. 
I may be adding LFOs for pitch modulation soon.  Synch is provided for
oscillator pairs NCO0/NCO1 and NCO2/NCO3 and are independantly enabled.

Device utilization is still around 57%, so there's still room for more stuff.

The GUI patch editor is also modified to include a slider for filter Q and
checkbox enables for synch.

-- ScottG

-------------------------------------------------------------

-- Scott Gravenhorst
-- GateMan I - Xilinx Spartan-3E Based MIDI Synthesizer
-- 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.




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