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<TITLE>My Midi controlled VCF module</TITLE>
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<P><FONT SIZE=2>Hello,</FONT>
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<P><FONT SIZE=2>I've written some preliminary software to test if it's possible what I want, and as things look now, it will be possible.</FONT></P>
<P><FONT SIZE=2>The unit will have 3 LFOs with 5 different waveforms (ramp up,ramp down,saw,square and random). Each LFO has a speed and depth control.</FONT></P>
<P><FONT SIZE=2>Each LFO's output can be routed to one destination but each destination can have up to 3 sources. The destinations are LFO 1/2/3 speed or depth, filter cutoff and filter resonance.</FONT></P>
<P><FONT SIZE=2>It possible to have all 3 LFO to modulate the filter cutoff frequency. This must give interesting filter sweeps!</FONT>
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<P><FONT SIZE=2>LFO outputs are bipolar.</FONT>
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<P><FONT SIZE=2>Each parameter has its own potentiometer, this will give 8 pots. Each pot sends out MIDI controller data, which the unit can also receive. Of course, when a controller message changes a parameter, the physical pot position does not reflect the actual parameter value, a LED above each pot will light up to indicate this.</FONT></P>
<P><FONT SIZE=2>The modulation matrix (I don't really have a good name for this, maybe virtual patching?) uses two buttons, and the waveform select for each LFO uses one button.</FONT></P>
<P><FONT SIZE=2>No LCD or so will be provided.</FONT>
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<P><FONT SIZE=2>I will use an Atmel AT89C52 microcontroller, with an AD7945 12 bit DAC that is also used for AD for the pots. (SAR principle). The uC has 8K flash memory, and needs no support logic.</FONT></P>
<P><FONT SIZE=2>Performance analyses show that calculating the LFO samples take the most of the processor time, approx. 40%.</FONT>
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<P><FONT SIZE=2>JJ</FONT>
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