[Sebastian Holzapfel] has designed an audio frontend (eurorack-pmod) for FPGA-based audio purposes, which is designed to suit into an ordinary Eurorack enclosure. The challenge, launched beneath CERN Open-{Hardware} License V2, is designed in KiCAD utilizing the AK4619VN four-channel audio codec by Asahi Kasei microdevices. (and guess what people, there’s loads of these in inventory!)

The AK4619 is an audio frontend machine, meant for computerized head unit purposes, and accommodates 4 audio ADCs and 4 DACs. These allow the eurorack-pmod to deal with 4 incoming and 4 outgoing channels on the identical time. With an I²S or PCM interface, which is connected to a PMOD connector on the rear, an exterior FPGA board of your alternative might be related, of which there’s fairly some alternative. [Sebastian] supplies some instance code focused on the iCEBreaker FPGA board which might all be dealt with by the Yosys toolchain. This offers with the main points of the AK4619 codec, in addition to a board-level calibration, to permit the person to focus on the appliance code. That could be a pure synthesizer, some sort of DSP audio impact, or one thing in between. The Verilog code itself is sort of simple, so must be simply moveable to every other FPGA board the person has entry to.

Some code for instance cores is offered, with a VCO, programmable filter, delay/decimator, and some different goodies, so loads of examples to start out with to your first FPGA synth challenge! For studying and simulation functions [Sebastian] has offered the mandatory setups to drive the VCV Rack audio simulator, in addition to a helpful information for working Verilog simulation inside VCV.

FPGA audio synthesis is nothing new round right here, however new tasks on this house are at all times thrilling. As for earlier works, right here’s one based mostly on an previous Xilinx Spartan 6 board, and one other for the newer Zynq.