This audio adaptor lets you easily add high quality 16 bit, 44.1 kHz sample rate (CD quality) audio to your projects with Teensy 3.0, 3.1, 3.2, 3.5 or 3.6. It supports stereo headphone and stereo line-level output, and also stereo line-level input or mono microphone input.
The Teensy Audio Library lets you use the input and output simultaneously together with a toolkit of audio processing objects, to easily create all types of sophisticated audio applications. You can play multiple sound files, create synthesized waveforms, apply effects, mix multiple streams and output high quality audio to the headphones or line out pins.
Teensy 3.x have the Cortex-M4 DSP instructions which provide plenty of computational power for real-time FFT (spectrum analysis), opening up the possibility of creating advanced sound-reactive projects.
Two of these 14x1 pins can be used to easily soolder the Teensy 3.x and audio board together.
A 14 pin socket and 14 pin header can be used to make them plug together.
An optional Thumbwheel Potentiometer can be added for volume or control an audio parameter.
Optional Add-Ons
The optional volume knob and line in/out header are also added.
Signals to Teensy
The audio chip, part number SGTL5000, connects to Teensy 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 Teensy3. The SGTL5000 operates in "slave mode", where all its clock pins are inputs.
The SD socket is accessed with 4 SPI pins. SCLK and MOSI are used at alternate locatoins. See the audio library examples for details on how to select these different pins. The SD card is useful for playing music. Sandisk and other good quality SD cards are capable of playing 2 WAV files simultaneously.
Wires for MCLK, BCLK, LRCLK, TX & RX should be kept short. The audio shield is meant to connect to Teensy through short pins. Wires can be used, but wires must be short to avoid problems.
The line in/out header uses a pinout compatible with the AC97 audio header on PC motherboards. The front panel cables from most PCs can be connected, or wires can be soldered directly to the pins.
Optional Memory Chip(s)
A W25Q128JV or W25Q128FV flash memory chip may be added on the bottom side. The Teensy Audio Library can play audio clips from this memory, using the SerialFlash library. This flash memory has much lower access latency than SD cards, which allows many sounds to be played simultaneously.
Future versions of the audio library may also use this low latency flash memory for wavetable synthesis.
Alteratively, a 23LC1024 RAM memory chip may be added. The Teensy Audio Library can use the RAM chip for a multi-tap delay line, up to 1.5 seconds. See this demo video for details.
