Nts player

NTS Web Radio Player

This is a standalone Wi-Fi connected web-radio player based on ESP-32. It was designed for the NTS.live radio which has 18 live stations (2 main channels + 16 infinite mixtapes).

It's built around the ESP32-S3 and a PCM5122 DAC, with firmware written in Rust and a 3D-printed enclosure. The design is made to be very simple to interact with: a single encoder with a large knob to select the station and change the volume.

A ring of LEDs show which station is selected and the current volume level. The click action of the encoder switches between the modes and allows to put the device to sleep.

Note: this device is not affiliated with NTS or Atonemo which have created a standalone player for NTS. Support your favorite radio by becoming a supporter or buying from the shop.

Features

• Streams MP3 web radio over HTTPS (e.g. NTS: 256 kbps, 44.1 kHz stereo)
• 18 stations on one detented encoder, one click per station
• 18-LED ring around the knob shows the current station (and volume in volume mode)
• Push the knob to toggle station / volume mode, long-press to sleep, press to wake
• Hold the devkit boot button for 5 s to erase all settings (Wi-Fi included) and restart
• Line out at up to about 1.5 Vrms on 3.5 mm and RCA, wired in parallel
  • This is meant as line out, not as headphones output, it expects a load of 1 kOhm or more.
  • The DAC can reach 2.1 Vrms, but the firmware limits the top volume step to -3 dB.
• Low sleep current (about 0.6 mA at 5 V): LED ring and DAC are power-switched in deep sleep
• Home Assistant "off" is a standby that keeps Wi-Fi on and breathes the station LED dimly, press the knob or turn it on in HA to wake
• Powered over USB-C (5 V)
• Wi-Fi setup through a portal on the nts-player access point
• Home Assistant control (power, station, volume) through the built-in ESPHome integration

Repository Layout

firmware/   Rust firmware (ESP-IDF, std)
kicad/      KiCad schematic and PCB for the carrier board
enclosure/  3d-printable enclosure parts
docs/       Datasheet links and devkit pinout

Pin Map

Avoided: strapping pins 0, 3, 45, 46; GPIO35–37 (octal PSRAM); GPIO19/20 (USB); GPIO38 (onboard RGB LED); GPIO43/44 (UART0).

Building and Flashing

This is a std (ESP-IDF based) Rust project. The ESP-IDF C SDK is downloaded and built automatically by the esp-idf-sys build script. Run all commands from the repository root.

Prerequisites with Nix

The flake provides a dev shell (x86_64 Linux only) with the Xtensa Rust toolchain from esp-rs (pinned in nix/esp-rust.nix), ldproxy, espflash and the tools needed by the ESP-IDF build:

nix develop

Prerequisites without Nix

Espressif's Rust on ESP book is the reference for the toolchain setup. TL;DR:

1. Install the ESP-IDF host dependencies

2. Install Rust with rustup.

3. Install espup and the Xtensa toolchain:

   cargo install espup --locked
   espup install

4. Activate the environment from espup. This has to be done in every new shell:

   . $HOME/export-esp.sh

5. Install the linker wrapper and the flashing tool:

   cargo install ldproxy --locked
   cargo install espflash --locked

   ldproxy is required by .cargo/config.toml to use espflash as the cargo runner.

ESP-IDF

The version is pinned in .cargo/config.toml:

[env]
ESP_IDF_VERSION = "v5.5.5"

On the first cargo build, the esp-idf-sys build script clones that tag into .embuild/ and downloads the matching ESP-IDF toolchains. This will take a few GBs of space and take a while the first time.

Build

cargo build --release

Flash and Monitor

Connect the board over USB, then:

cargo run --release

The runner configured in .cargo/config.toml invokes espflash flash --monitor, which flashes the firmware and then opens the serial monitor. To flash without the monitor, or from a script, give the port explicitly:

espflash flash --port /dev/ttyACM0 target/xtensa-esp32s3-espidf/release/nts-player

WSL

Pass the board through to WSL with usbipd-win. In PowerShell:

usbipd list                                         # find the board's bus ID
usbipd bind --busid <BUSID>                         # once, as administrator
usbipd attach --wsl --busid <BUSID> --auto-attach   # each session

Your WSL user must be in the dialout group to open /dev/ttyACM0.

License

• Hardware (kicad/) and enclosure (enclosure/): CC BY-NC-SA 4.0
• Firmware (firmware/): dual-licensed under MIT or Apache-2.0, at your option