This audio adapter lets you easily add high quality 16 bit, 44.1 kHz sample rate (CD quality) audio to your projects with a Teensy 4.0 . It supports stereo headphone and stereo line-level output, and also stereo line-level input or mono microphone input. The audio chip connects to Teensy 4.0 using 7 signals. The I2C pins SDA and SCL are used to control the chip and adjust parameters. Audio data uses I2S signals, TX (to headphones and/or line out) and RX (from line in or mic), and 3 clocks, LRCLK (44.1 kHz), BCLK (1.41 MHz) and MCLK (11.29 MHz). All 3 clocks are created by the Teensy. The SGTL5000 chip operates in "slave mode," where all its clock pins are inputs.