Fynthesizer

Fynthesizer is a 3xOSC-like FPGA synthesizer that generates waveforms using up to 3 oscillators and allows you to play up to 12 keys simultaneously. You can fine-tune various parameters, such as ADSR, pitch offset of secondary oscillators, volume, and more to shape the waveform.

A MIDI controller is supported, but you may need to modify the hard-coded MIDI messages in the top modules to adapt to your controller. This project uses the Native Instrument Komplete Kontrol M32.

We have provided a GUI panel in res/QtSynth.py. The panel interface is shown below, displaying the adjustable parameters.

For more details and specifications, please refer to Final_Report.pdf.

Environment

• FPGA board: Nexys DDR4 (Nexys A7)
• FPGA chip: xc7a100tcsg324-1
• Operating system: Ubuntu 20.04 (full project with test cases), Windows 11 (partial test cases. To run on Windows, modify res/QtSynth.py which uses the pySerial library)
• Development environment: Vivado 2020.2

Hardware Connection

Recommendation: Use a single-channel-to-dual-channel 3.5mm jack to ensure both speakers play sound.

Usage

Clone this project and use the .bit and .bin files in the bitstream/ folder to program your device. Alternatively, download the project file from the GitHub Release and open the Vivado project directly.

To compile this project in Vivado:

1. Add all files in src/hdl as source files.
2. Add all files in src/xdc as constraint files.
3. Choose one of the top module .vhd files in src/hdl/top_modules and set the corresponding .xdc file in src/xdc as target.

The provided top modules are:

• Fynthesizer3x.vhd: 3xosc-like synthesizer (Recommended)
• Fynthesizer3x_inst.vhd: 3xosc-like synthesizer with musical instrument waveforms (Recommended)
• Fynthesizer.vhd: Single oscillator synthesizer
• core_top.vhd: Test file for the synthesizer core, controlled by the 4 buttons and 16 switches on the board
• instrument_top.vhd: Test file for the synthesizer core with instrument waveforms, controlled by the 4 buttons and 16 switches on the board

For the Python files provided in res:

cd res

First, install the dependencies:

pip install mido serial pyqt5

Then, to call the Qt panel:

# If you set Fynthesizer3x as the top module
python QtSynth.py

# If you set Fynthesizer3x_inst.vhd as the top module
python QtSynth_inst.py

These two panels only differ in the labels in the waveform selection boxes.

If you don’t have a MIDI controller, you can use the Virtual MIDI Piano Keyboard (vmpk) instead.

sudo apt install vmpk

To play a MIDI file directly to the synthesizer:

python play_midi_file.py

References

Thanks to the following projects for their inspiration and help:

• docquantum/skrach-synth: An FPGA synthesizer with MIDI support
• jakubcabal/uart-for-fpga: Simple UART controller for FPGA written in VHDL

Contributors