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RetroCade System On A Chip Synth for Generating Audio!

Monday, February 22, 2016

If you're a hardware hacker and/or musician, you may be interested in this offering by Gadget Factory. It's called RetroCade Synth! The RetroCade Synth puts classic audio chips in the hands of musicians and hackers alike, thanks to audio chips that are open source VHDL implementations which recreate the Commodore 64 SID chip and the Yamaha YM-2149 chip inside the FPGA.
The heart of the RetroCade Synth is the ZPUino soft processor which is a 32 bit soft processor running at 100Mhz. It uses a modified version of the Arduino IDE which allows everything to be controlled by a sketch. The Sketch defines the RetroCade's firmware and handles all MIDI functionality and implements support for all file formats.


By connecting the classic audio chip peripherals to the ZPUino's Wishbone bus, the RetroCade synth is essentially a System on a Chip solution for generating audio! The RetroCade synth works by snapping a Papilio Pro or Papilio One onto a RetroCade MegaWing to make the RetroCade Synth work. The main features of the RetroCade are as follows:
MIDI
The Midi section of the RetroCade implements three MIDI jacks; MIDI IN, MIDI OUT, and MIDI THROUGH. MIDI In is used to connect MIDI instruments such as a MIDI Keyboard, MIDI control board, or MIDI sequencer to the RetroCade synth to send MIDI notes and Control Changes that tell the RetroCade what audio to output. MIDI Through is connected to the MIDI In port and passes everything that comes in over the MIDI In port back out so MIDI devices can be daisy chained together. MIDI Out can be used by the RetroCade to output MIDI data such as timing, change control's or notes.
Sound
The RetroCade features two top of the line 1/4" Neutrik audio jacks with a low pass filter combined with a high speed Delta-Sigma DAC, which allows high quality audio output to be realized. The high speed of the FPGA clock allows the FPGA to do the heavy lifting of the Digital to Analog conversion.

LCD
The RetroCade features a 16x2 HD44780 compatible Character LCD, used to provide standalone control and feedback for the RetroCade. A standard backlight is provided for easy visibility in low light situations.

Fingertip Joystick
RetroCade's four directional TPA511GLFS digital joystick allows for easy menu navigation.

Micro SD
The MicroSD (Secure Digital) socket expands the RetroCade with GigaBytes worth of storage space for the audio and configuration files.

Analog Input
16 Analog inputs allow the RetroCade to be turned into a custom controller and the Analog header allows you to connect up to sixteen analog devices such as sliders, knobs, and analog joysticks. The header is even compatible with the Seeed Studio analog Grove devices when used with a Grove to Brick adapter. The 16 analog channels are implemented with two ADC088S102CIMTX 8-bit, 8 Channel, SPI ADC's that are capable of sampling at speeds up to 1Msps.
The RetroCade synth is built on the Open Source Papilio FPGA boards which uses Papilio Wings like Arduino Shields. Everything that you need to load bit files over USB is integrated into the board so all you have to do is load the RetroCade bit file and you have the RetroCade Synth. If you like, you can swap out the RetroCade MegaWing for the Arcade MegaWing, load the PacMan bit file and you have the PacMan Motherboard (a completely new hardware with minimal fuss).
The RetroCade Synth functions are controlled from a MIDI controller, though a control dashboard (made with SynthMaker) is also provided with RetroCade that can be used as a VSTi Plugin, a standalone executable, or in SynthMaker to visually control all the various parameters the synth has to offer.

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