Installation and setup

Installing dependencies

CMake (3.20 or newer), Python3 and an ARM toolchain are required to build the project.

To install the dependencies on Debian Bookworm, run:

apt install cmake python3 python3-venv build-essential gcc-arm-none-eabi libnewlib-arm-none-eabi libstdc++-arm-none-eabi-newlib libusb-1.0-0-dev

Clone the audio-latency-tester repository:

git clone https://github.com/antmicro/audio-latency-tester.git
cd audio-latency-tester

To run the project, it is also required to install following Python packages:

python3 -m venv .venv
source .venv/bin/activate
pip install pyusb libusb click librosa numpy soundfile argparse

Building RP2040 firmware

Install pico-sdk and pico-extras:

git clone --recurse-submodules --branch 2.1.0 https://github.com/raspberrypi/pico-sdk.git
git clone --recurse-submodules --branch sdk-2.1.0 https://github.com/raspberrypi/pico-extras.git

The build system uses environment variables to find these repositories:

export PICO_SDK_PATH=$(pwd)/pico-sdk
export PICO_EXTRAS_PATH=$(pwd)/pico-extras

To build the project, run:

cmake -S . -B build
cmake --build build -j$(nproc)

If the build succeeded, the following files should be present in build directory:

  • build/audio_out/rp2040-i2s-timestamp.elf

  • build/audio_out/rp2040-i2s-timestamp.uf2

  • build/audio_in_pdm/rp2040-i2s-timestamp-audio-in.elf

  • build/audio_in_pdm/rp2040-i2s-timestamp-audio-in.uf2

Flashing hardware

Install Picotool

In order to flash the devices, picotool is required. The installation instructions can be found in this README.

Flashing firmware to the board

The Audio latency tester board consists of 2 independent RP2040 MCUs - one for audio input, other for audio output. Each of them has to be flashed with the .uf2 file prepared in the previous steps.

Flashing Audio input firmware

  • Connect MCU-1 USB-C (the port labeled as USB-C Mics) to your PC. LEDs should light up.

Figure 2 MCU-1 USB-C connection

  • Press and hold the MCU-1 BOOTSEL (SW2) button.

  • Press and release the MCU-1 RST (SW1) button.

  • Release the MCU-1 BOOTSEL button.

  • With lsusb, you should see that the device is recognized as a USB device Raspberry Pi RP2 Boot

Bus 001 Device 099: ID 2e8a:0003 Raspberry Pi RP2 Boot

  • Use picotool to flash the device and execute the program immediately:

picotool load -x build/audio_in_pdm/rp2040-i2s-timestamp-audio-in.uf2

Expected output:

Loading into Flash:   [==============================]  100%

The device was rebooted to start the application.

  • With lsusb, you should see that the device is recognized as a USB device with ID cafe:4010

Bus 003 Device 012: ID cafe:4010 Raspberry Pi RP2040

Flashing Audio output firmware

  • Disconnect MCU-1 USB-C port.

  • Connect MCU-2 USB-C (the port labeled as USB-C Speaker) to your PC. LEDs should light up.

Figure 3 MCU-2 USB-C connection

  • Press and hold the MCU-2 BOOTSEL (SW4) button.

  • Press and release the MCU-2 RST (SW3) button.

  • Release the MCU-2 BOOTSEL button.

  • With lsusb, you should see that the device is recognized as a USB device Raspberry Pi RP2 Boot

Bus 001 Device 101: ID 2e8a:0003 Raspberry Pi RP2 Boot

  • Use picotool to flash the device and execute the program immediately:

picotool load -x build/audio_out/rp2040-i2s-timestamp.uf2

  • With lsusb, you should see that the device is recognized as a USB device with ID cafe:4011

Bus 003 Device 012: ID cafe:4011 Raspberry Pi RP2040
Last update: 2025-05-22