I2S driver demo running in Zephyr

Copyright (c) 2020-2021 Antmicro

I2S sound driver allows endpoint applications to receive and transmit audio PCM frames.

We can distinguish two main parts of the sound system.

• The I2S core written completely in Migen, which can be connected to the LiteX SoC. It enables I2S hardware support for sound transmission.
• The I2S Zephyr driver that allows collecting and transmitting sound samples using the real-time operating system.

Devices

To use the driver you need an FPGA board that is supported by the LiteX SoC build system and the I2S codec. The driver was tested with:

• Arty-7 board
• Pmod-i2s2

The following instructions pertain to a setup consisting of those devices.

Device configuration

The I2S2 Pmod can be connected to any Pmod connector on the Arty-7 board.
By default, LiteX is configured to support Pmod on JA connector.
The PMOD I2S2 jumper has to switch the device into master mode. To do so, put the jumper in the MST position.
This allows the device to generate required signals using its internal circuits.

Example setup

Prerequisites

Get all required submodules:

git submodule update --init --recursive

Install dependencies:

apt update
apt install build-essential bzip2 python3 python3-dev python3-pip
pip3 install pyyaml

Building

Install the Vivado toolchain. You can download Vivado using this link. The 2017.3 or newer version of Vivado is recommended.

Run below commands:

source ${PATH_TO_VIVADO_TOOLCHAIN}/settings64.sh
./build_i2s_zephyr.sh

Output will be placed in binaries directory.

• Gateware - arty.bit
• Firmware - zephyr.bin