# The Adafruit Boards
Any real-time audio application running on the microcontroller will need to acquire data from a source (for instance, a microphone) and deliver data to an output sink (for instance, an digital-to-analog converter connected to a loudspeaker) that we can listen to. Here is a brief description of the components we selected.
## The microphone breakout board
The component used to capture sound is the [I2S MEMS Microphone Breakout](https://learn.adafruit.com/adafruit-i2s-mems-microphone-breakout/overview) by Adafruit. The actual microphone on this mini-board produces an *analog signal* (continuous in time and amplitude) but the device also contains an Analog-to-Digital Converter that returns a *digital* signal (discrete in time and amplitude), which is the format we need in order to pass the data to our microcontroller. We will describe the component in more detail [later](https://hwlab.learndsp.org/audio-peripherals/microphone).
## The DAC breakout board
The microcontroller accepts and produces digital signals; in order to playback its output on a pair of headphones, it is necessary to create an analog signal and this can be achieved via a Digital-to-Analog Converter (DAC). We will use Adafruit's [I2S Stereo Decoder Breakout](https://learn.adafruit.com/adafruit-i2s-stereo-decoder-uda1334a/overview), which contains the DAC, an audio jack for connecting headphones, and the necessary additional components. We will describe the DAC in more detail [later](https://hwlab.learndsp.org/audio-peripherals/dac).
