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Teensy Audio Board for Teensy 4.0

by PJRC
$16.99
SKU 3442

This audio adaptor lets you easily add high quality 16 bit, 44.1 kHz sample rate (CD quality) audio to your projects with the Teensy 4.0 (Rev D). 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.

Function Teensy 4.0 Pins Rev D Shareable
Audio Data 7, 8, 20, 21, 23  
Audio Control 18, 19 SDA, SCL (other I2C chips) 
Volume Pot 15 (A1)
SD Card 10, 11, 12, 13 MOSI, MISO, SCK (other SPI chips) 
Memory Chip 6, 11, 12, 13 MOSI, MISO, SCK (other SPI chips) 

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).

Signal Rev D (Teensy 4.0) Function
MCLK 23 Audio Master Clock, 11.29MHz
BCLK 21 Audio Bit Clock 1.41 or 2.82MHz
LRCLK 20 Audio Left/Right Clock, 44.1MHz
DIN 7 Audio Data from Teensy to Audio Shield
DOUT 8 Audio Data from Audio Shield to Teensy
SCL 19 Control Clock (I2C)
SDA 18 Control Data (I2C)
SCK 13 Data Storage (SPI) Clock
MISO 12 Data Storage (SPI) from SD/MEM to Teensy
MOSI 11 Data Storage (SPI from Teensy to SD/MEM
SDCS 10 Chip Select (SPI) for SD Card
MEMCS 6 Chip Select (SPI) for Memory
Vol 15 / A1 Volume Thumbwheel (analog signal)

Teensy Audio Library

In September 2019, Rev D was created for Teensy 4.0. The circuitry is the same as Rev C, but the I2S digital audio signals and SPI signals for the SD card are routed to the pins Teensy 4.0 uses.

Teensy Audio Board for Teensy 4.0