Audio Arduino - an ALSA (Advanced Linux Sound Architecture) Audio Driver for FTDI-based Arduinos

A contemporary PC user, typically expects a sound card to be a piece of hardware, that: can be manipulated by ’audio’ software (most typically exemplified by ’media players’); and allows interfacing of the PC to audio reproduction and/or recording equipment. As such, a ’sound card’ can be considered to be a system, that encompasses design decisions on both hardware and software levels that also demand a certain understanding of the architecture of the target PC operating system. This project outlines how an Arduino Duemillanove board (containing a USB interface chip, manufactured by Future Technology Devices International Ltd [FTDI] company) can be demonstrated to behave as a full-duplex, mono, 8-bit 44.1 kHz soundcard, through an implementation of: a PC audio driver for ALSA (Advanced Linux Sound Architecture); a matching program for the Arduino’s ATmega microcontroller and nothing more than headphones (and a couple of capacitors). The main contribution of this paper is to bring a holistic aspect to the discussion on the topic of implementation of soundcards also by referring to open-source driver, microcontroller code and test methods; and outline a complete implementation of an open yet functional soundcard system.