The Codec Zero HAT is a Raspberry Pi Zero-sized board but it also includes the HAT’s EEPROM allowing for auto-configuration of the Linux environment if needed.
The Codec Zero HAT delivers bi-directional digital audio signals (I2S) between the Raspberry Pi and onboard Dialog Semiconductor DA7212. It supports a range of input and output devices from a built-in MEMS microphone, mono Electret microphone or mono speaker (1.2W / 8Ω).
It also has GREEN (GPIO23) and RED (GPIO24) LEDs, that can be used for status and a tactile button (GPIO27) that can be used to start an event.