Several devices in the SigmaDSP? family include general-purpose input/ output (GPIO) pins. These pins can be connected to external hardware elements, such as LEDs, push-buttons, or rotary encoders.
Some of the GPIO pins may be multiplexed to an auxiliary ADC, allowing direct connection of a potentiometer or an analog control voltage to the IC. Each pin can operate in a variety of modes, including open-collector output, inputs with debounce, and outputs driven directly by the control port.

Within the SigmaStudio? graphical programming software, GPIO pins can be assigned to control or be controlled by various parts of the audio signal processing program. The functionality of the pins can be changed during run-time operation of the device. Utilization of the GPIO pins for user interface functionality can reduce or eliminate the need for a microcontroller. This can greatly reduce the cost of a simple audio system.
This application note begins by describing the hardware inter-facing necessary to effectively use the GPIOs. In addition, this application note discusses several cases that could greatly reduce the complexity of a SigmaDSP audio system.