FUI Audio DAC Wiki
FPGA-Based USB-Input Audio Digital to Analogue Converter
Status: Pre-Alpha
Brought to you by:
jptaylor
Menu
▾
▴
Introduction
The FUI Audio DAC project is under active development. Implementation and design details are subject to change without notice.
Introduction
1. Overview
The FUI Audio DAC is an open-hardware and -firmware project that implements a USB-input fully-digital class-D audio amplifier. A Microchip PIC-based remote control is also included.
The generic Windows USB audio driver is used to stream 48 kSps stereo audio to the amplifier. The generic Windows HID driver is used to interface a volume control knob and various buttons to the computer. These buttons are implemented on a remote control, which is implemented by means of an off-the-shelf 433 MHz ASK module (FS1000A and C218D001C pair). Intended functions include volume up, volume down, play/pause, next track, previous track and stop controls.
Volume control is implemented as a combination of bus voltage control and audio stream gain control.
The block diagram below provides a system overview. The FPGA used for this project is an Altera Max 10, which is on a BeMicro Max 10 development kit. The microprocessor used for the remote control is a Microchip PIC16F676.
2. Firmware
All processing is done on FPGA, including the USB-physical, USB-SIE, HID interface, clock-recovery, bus voltage regulation, noise-shaping and PWM output. An overview of the firmware is provided in the block diagram below.
3. USB Vendor ID and Product ID
At present, the project uses the Test ID provided by PID Codes. It is not unique and may therefore not be used outside test environments.
4. Development Software
The project is developed using:
- TinyCAD
- FreePCB (or you can use the fork)
- MPLAB-X, which comes with a free version of the XC compiler
- Quartus Prime Lite
- InkScape
The source is available from the git repository and GitHub.
