i2s_codecs

Abstract

This repository is a collection of hardware and software for evaluating I2S codecs for use in digital audio projects. I've been using codecs for personal and commercial applications for more than a decade now and I've seen a lot of them come and go. Recently several of my go-to codecs went EOL and I had to dive back into the distributors sites to find a new one to use for some upcoming projects. The first one I tried had some very odd behavior so I picked a few more, built some breakout boards and a little I2S signal generator for comparing them all on even footing. The designs here are the result of that effort.

Hardware

There are two subdirectories here with KiCAD hardware designs that I used:

• codec_pmods - these are simple breakout boards for a number of different codecs, some of which are currently available, some are obsolete. They are small 2-layer boards intended to provide minimal support for the codec devices with little to no attention to audio signal conditioning. The I2S interface is through a standard 12-pin (8 signals + 4 power & ground) PMOD connector that also provides 3 GPIO pins that support I2C or bitbang configuration protocols that some codecs require for startup.
• rp2040_i2s_tester - this is a KiCAD design for an RP2040 MCU that can drive the 12-pin PMOD with appropriate I2S, I2C or bitbang as well as 3.3V power. It uses a USB-C connector for power and bootloading but also provides a Qwiic I2C connector, a blinky LED and a user-defined button for mode selection.

Software

The directory Firmware contains a Raspberry Pi SDK project with basic firmware for the rp2040_i2s_tester board.

Going Further

This is bare-bones stuff but can support more complex stuff in the future. I may investigate USB Audio class drivers for interfacing the codecs to a host. There are also a wide range of other codecs I may add to the list of breakouts. Time will tell.