This evaluation board provides full access to all analog and digital I/Os on the ADAU1781. The SigmaDSP is controlled by Analog Devices, Inc., SigmaStudio™ software, which interfaces to the board via a USB connection. This evaluation board can be powered either over the USB bus or by a single 3.8 V to 6 V supply, which is regulated to the voltages required on the board. The PC board is a 4-layer design, with a single ground plane and a single power plane on the inner layers. The board contains onboard microphones and speaker, and connectors for external microphones and speaker. The master clock can be provided externally or by the on-board 12.288 MHz active oscillator.