SteveD

Minimoog Synth

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Hi all,

I'm using the Papilio Pro/Retrocade hardware in a slightly different way. I am attempting to replicate a Minimoog synth using DSP techniques. The source code is available at https://github.com/sjdavies/minimoog.

 

So far the system does the following:

1) performs digital->analog conversion using a 12 bit delta-sigma DAC (as per Xilinx doco).

2) generates a sawtooth/square/pulse waveform for a given MIDI note number.

3) samples all 16 analog port pins, latching each value in distributed RAM.

 

Not much but it's a start.

 

Next tasks:

1) clean up the clock logic

2) get a MIDI keyboard attached and working.

 

Enjoy,

Steve

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Steve, that sounds awesome! I'd love to integrate your synth into the RetroCade when it is done. If we turn it into a wishbone interface then it should plug right into the existing RetroCade framework.

 

Jack.

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Hi Jack,

sounds good, always happy to share.

 

In case anyone is interested:

1) clock logic cleaned up

2) work started on oscillator bank

3) MIDI keyboard interface not yet started

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Hi all,

just comitted a fix to the ADC logic and it is now working correctly.

 

Module ADC.v contains a state machine that reads each of the 8 analog pins in turn and stores the 8 bit value in a dual ported RAM. While based on the Papilio Pro/Retrocade wing combo it wouldn't take too much fiddling to adapt it to other platforms.

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Hmmm, its saying that the github project does not exist... When I get some of the things on my plate cleared off I would love to take a look at this and see if it can be added to the RetroCade as a wishbone peripheral.

 

Jack

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Regarding the Sigma Delta: I switched to opencores 2-level implementation, it has less noise on lower volume. If you experience noise, try switching to it.

 

Alvie

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