The Audio Codec Board - PROTO is a development tool for the WM8731 Audio Codec, ideal for use in embedded applications which require audio playback. The on-board Audio Codec WM8731 provides stereo line and mono microphone level audio inputs. This module also uses stereo 24-bit multi-bit sigma delta ADCs and DACs with oversampling digital interpolation and decimation filters. Stereo audio outputs are buffered for driving headphones from a programmable volume control. Line level outputs are also provided along with anti-thump mute and power up/down circuitry. The device is controlled via 2 wire (I2C) or 3 wire (SPI) serial interface.