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NRF54L15 Arduino core for XIAO nRF54L15 (Zephyr-based )

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IMPORTANT: first-time installation + first compile can be slow and may look stalled. Let it finish.

Disk usage warning: after first setup/compilation, required disk space is about 9 GB (SDK/toolchain/workspace + build cache).

Windows can be much slower because real-time protection scans large SDK/toolchain files. Recommended: use Linux. On Windows, add this core/tools path as an antivirus exception, or temporarily disable real-time protection only for first setup/compile.

Windows recommendation: use the script install method only (`install_windows.bat`). Sometimes first compilation on Windows fails with `ECONNRESET` due to a bug in the Arduino IDE Windows client (Electron-based). After one successful first compilation, switching back to Arduino IDE usually works.

Arduino Core for nRF54L15 (Zephyr-Based)

A clean, lightweight Arduino core for Nordic Semiconductor nRF54L15 microcontrollers. This repository intentionally keeps heavyweight SDK/toolchain content out of source control and release archives.

Build/runtime basis:

  • Arduino-compatible core APIs and libraries in this repository.
  • Zephyr + NCS components are used by the build pipeline and are bootstrapped when needed.
  • Release/source archives remain publishable and lightweight by excluding bundled SDK payloads.

XIAO nRF54L15 Board Reference

XIAO nRF54L15 pin and board definition

Hardware documents:

Features

  • ✅ No bundled SDK payloads - NCS/Zephyr SDK are bootstrapped at build time when needed
  • ✅ Lean distribution - Boards Manager archive excludes generated SDK/workspace payloads
  • ✅ Core Arduino API - Standard digital, timing, serial, Wire, and SPI APIs
  • ✅ Board helper library - Sleep/system-off, watchdog, reset-cause, antenna, radio-profile, and peripheral power-gating helpers
  • ✅ 64MHz Cortex-M33 - Fast ARM core with DSP instructions
  • ✅ 512KB Flash, 64KB RAM - Plenty of memory for your projects
  • ✅ CMSIS-DAP debug - Works with built-in debugger on XIAO boards
  • ✅ Cross-platform uploader - Auto runner selects pyOCD then OpenOCD
  • ✅ Board Tools menu - Upload method, CPU frequency, antenna, radio profile
  • ✅ Curated board-specific examples - Arduino IDE menu is focused on XIAO nRF54L15 BLE/radio/power/GPIO/Sense workflows

Supported Boards

Seeed Studio XIAO nRF54L15

  • 18 GPIO pins with multi-function capabilities
  • Built-in RGB LED (NeoPixel)
  • Built-in user button
  • SPI, I2C, UART peripherals
  • Bluetooth API library (BLE advertise/scan/peripheral examples included)
  • BLE central API support (BLE.connect(...), BLE.disconnect(), BLE.connectLastScanResult(...))
  • Bluetooth scan filter APIs (BLE.setScanFilterName(...), BLE.setScanFilterAddress(...)) for deterministic range probing
  • Bluetooth scan callback API (BLE.scanForEach(...)) for streaming all advertisers in dense RF environments
  • IEEE 802.15.4 library (IEEE802154) for channel/PAN/address/tx-power config + scan callbacks
  • Low-power helpers + watchdog API (XiaoNrf54L15)
  • CPU frequency + power profile helpers (cpuFrequencyHz, cpuFrequencyFromToolsHz, setCpuFrequencyHz, applyPowerProfile)
  • Watchdog compatibility library (Watchdog.begin(...), Watchdog.feed())
  • 12-bit ADC with 8 channels
  • 4x PWM outputs

Seeed Studio XIAO nRF54L15 Sense

  • Everything from XIAO nRF54L15 plus onboard sensors
  • 6-DoF IMU (LSM6DS3TR-C)
  • Digital microphone (MSM261DGT006, PDM/DMIC)
  • Dedicated board option in Arduino IDE: XIAO nRF54L15 Sense (Zephyr-Based)
  • Curated Sense examples under Examples > Sense

Installation

Method 1: Manual Installation (Linux/macOS recommended)

  1. Download or clone this repository
  2. Copy the nrf54l15 folder to your Arduino hardware directory:
    • Linux: ~/Arduino/hardware/
    • macOS: ~/Documents/Arduino/hardware/
    • Windows: not recommended (use Method 3 script install instead)

The folder structure should look like:

Arduino/
└── hardware/
    └── nrf54l15/
        └── nrf54l15/
            ├── boards.txt
            ├── platform.txt
            ├── cores/
            ├── variants/
            ├── libraries/
            └── tools/
  1. Restart Arduino IDE
  2. Select Tools > Board > XIAO nRF54L15 (Zephyr-Based - NO BLE)

Method 2: Arduino IDE (Boards Manager, Linux/macOS recommended)

  1. Open File > Preferences > Additional boards manager URLs
  2. Add this package index URL (copy/paste as one line): 
    https://raw.githubusercontent.com/lolren/NRF54L15-Arduino-core/main/package_nrf54l15_zephyr_based_index.json
  3. Open Tools > Board > Boards Manager
  4. Search for Seeed nRF54L15 (Zephyr-Based) and install
  5. Select Tools > Board > XIAO nRF54L15 (Zephyr-Based - NO BLE)

Arduino IDE support:

  • Linux
  • macOS

Windows warning:

  • Sometimes first compilation on Windows fails with ECONNRESET due to a bug in the Arduino IDE Windows client (Electron-based).
  • Workaround: run first setup + first compile with Method 3 (install_windows.bat) or with Rewritto IDE (Qt6): https://github.com/lolren/rewritto-ide.
  • After one successful first compilation, switching back to Arduino IDE usually works.

Method 3: Setup Scripts (Standalone)

These scripts are independent from Boards Manager installation. Use them when you want guided host setup plus first-time SDK/bootstrap warmup before IDE compile/upload.

Linux:

bash ./install_linux.sh

Windows (Command Prompt):

install_windows.bat

Root launcher scripts:

  • install_linux.sh -> runs tools/install/linux_prereqs.sh
  • install_windows.bat -> runs tools/install/windows_prereqs.bat

tools/install/windows_prereqs.bat has editable variables at the top for:

  • Python download/version and installer args
  • Git download/version and installer args
  • CMake download/version and installer args
  • Winget package IDs

Both scripts default behavior:

  • Ensures Python, Git, CMake, DTC, and Ninja are installed (auto-installs if missing)
  • Copies this core into <Arduino data>/packages/<vendor>/hardware/nrf54l15/<version>
  • Preserves existing tools/ncs and tools/zephyr-sdk cache content on reruns
  • Bootstraps NCS workspace + Zephyr SDK
  • Installs required Zephyr Python build dependencies into tools/pydeps automatically
  • Runs a one-time Zephyr warmup build so IDE compiles are sketch-focused
  • Detects Arduino IDE (if installed)
  • Detects Arduino data folder (Arduino15)

Windows-only behavior:

  • Uses a short default Zephyr build cache path on Windows (%LOCALAPPDATA%\nrf54l15-build) to avoid path-length build failures

Linux/Windows script options:

  • --skip-core-copy to keep using the repo core path without copying
  • --skip-bootstrap to skip NCS/SDK download and warmup build
  • --help to print usage

Linux/Windows script env overrides:

  • ARDUINO_DATA_DIR to set explicit Arduino data directory
  • ARDUINO_PACKAGE_VENDOR to set package vendor folder (default: nrf54l15)

Windows build-path overrides:

  • ARDUINO_ZEPHYR_BUILD_DIR to set an explicit build directory
  • ARDUINO_NRF54L15_BUILD_ROOT to change the default short Windows build-root

Troubleshooting if the core does not appear in Boards Manager:

  • Ensure the URL above is added as one full line.
  • Search seeed (3 e's) or nrf54l15 in Boards Manager.
  • If you previously installed this core manually, remove/rename ~/Arduino/hardware/nrf54l15 (or move it outside hardware/) and refresh Boards Manager.
  • If Zephyr build paths are mixed between your local repo and Arduino15/packages/..., clear stale ZEPHYR_BASE and rerun: Windows CMD: set ZEPHYR_BASE= PowerShell: Remove-Item Env:ZEPHYR_BASE -ErrorAction SilentlyContinue

To generate release archive + checksum + updated package index before publishing:

python3 tools/release_boards_manager.py --version <new_version> --repo lolren/NRF54L15-Arduino-core

To run a local fresh-machine Boards Manager smoke test:

python3 tools/ci_fresh_machine_smoke.py

To verify release reproducibility (deterministic archive + index content):

python3 tools/check_release_reproducible.py

To create a clean sync folder (without local SDK/cache artifacts) and zip it for manual GitHub upload:

python3 tools/export_sync_bundle.py --clean --zip

Default output:

  • Folder: sync_export/NRF54L15-Arduino-core-sync
  • Zip: sync_export/NRF54L15-Arduino-core-sync.zip

Toolchain Requirements

This core bootstraps required NCS/Zephyr SDK components automatically on first build. No globally installed arm-none-eabi-* toolchain is required.

Host prerequisites:

Bootstrap cache behavior:

  • Changing Tools menu options (for example BLE enabled/disabled) reuses cached SDK/NCS data.
  • Updating the core version via Boards Manager reuses the same cache under <Arduino data>/packages/<vendor>/tools/ when possible.
  • Override cache location with ARDUINO_NRF54L15_SHARED_TOOLS_DIR.

Uploading Firmware

The XIAO nRF54L15 has a built-in CMSIS-DAP debugger. You can upload firmware using:

Via Arduino IDE

  1. Select Tools > Upload Method > Auto (recommended)
  2. Click the Upload button

Via Command Line (pyocd)

pyocd load -t nrf54l15 firmware.hex --format hex

Via Command Line (openocd)

openocd -f tools/openocd/nrf54l15.cfg -c "program firmware.hex verify reset"

Tools Menu (Board-Specific)

The clean core exposes these Arduino IDE options:

  • Upload Method: Auto (Recommended), pyOCD (CMSIS-DAP), OpenOCD (Experimental)
  • CPU Frequency: 64 MHz (Default), 128 MHz (Experimental)
  • Antenna: On-board Ceramic, External U.FL
  • Radio Profile: Radio Disabled, BLE Only, 802.15.4 Only, BLE + 802.15.4

For lowest active current, keep CPU Frequency = 64 MHz and use Power/LowPowerProfiles.

When Radio Profile is BLE Only, 802.15.4 Only, or BLE + 802.15.4, the build automatically enforces a 128 MHz radio-safe clock profile.

OpenOCD is marked experimental for nRF54L15 because upstream flash support is incomplete. If OpenOCD upload fails, the uploader falls back to pyOCD automatically when available.

To sync this local core into your Arduino sketchbook hardware path:

rsync -a --delete /home/lolren/Desktop/Xiaonrf54l15/Nrf54L15_clean/hardware/nrf54l15/ /home/lolren/Arduino/hardware/nrf54l15/

Pin Mapping (XIAO nRF54l15)

Arduino Pin Port/Pin Functions
D0 P1.04 GPIO
D1 P1.05 GPIO
D2 P1.06 GPIO
D3 P1.07 GPIO
D4 P1.10 GPIO, I2C SDA
D5 P1.11 GPIO, I2C SCL
D6 P2.08 GPIO, PWM, UART TX
D7 P2.07 GPIO, PWM, UART RX
D8 P2.01 GPIO, PWM, SPI SCK
D9 P2.04 GPIO, PWM, SPI MISO
D10 P2.02 GPIO, PWM, SPI MOSI
D11 P0.03 GPIO
D12 P0.04 GPIO
D13 P2.10 GPIO
D14 P2.09 GPIO
D15 P2.06 GPIO
D16 P2.00 LED_BUILTIN (active-low)
D17 P1.02 Built-in Button

Analog Pins

  • A0-A7: ADC channels 0-7 (map to various GPIO pins)

Serial Output

The XIAO nRF54L15 uses USB CDC for serial communication. The board appears as:

  • Linux: /dev/ttyACM0
  • macOS: /dev/cu.usbmodem...
  • Windows: COMx
void setup() {
    Serial.begin(115200);
    Serial.println("XIAO nRF54L15 ready!");
}

void loop() {
    Serial.println("Hello!");
    delay(1000);
}

Examples

The core includes several examples:

  • BLE/BLEScanTest - quick BLE scan sanity check
  • BLE/BLEAdvertiseTest - quick BLE advertising sanity check
  • BLE/BLEScanMonitor - stream all scan hits in each window (scanForEach)
  • BLE/BLECentralMonitor - board-level BLE central loop for real-device tests
  • Radio/AntennaControl - runtime ceramic/U.FL antenna switch
  • Radio/RadioProfileInfo - print Tools menu radio/profile/antenna settings
  • Radio/IEEE802154FeatureProbe - board-level 802.15.4 probe/scan example
  • Power/battery - VBAT_EN + A7 battery monitor sample
  • Power/LowPowerFeatures - sleep + wake behavior checks
  • Power/LowPowerProfiles - button-switchable low-power duty profiles
  • Power/PeripheralPowerGating - manual peripheral suspend/resume shell
  • Power/WatchdogSleepWake - watchdog + sleep + reset-cause validation
  • GPIO/InterruptButton - interrupt-driven button handling on board pin map
  • libraries/Bluetooth/examples/ - BLE API examples for the clean core
  • libraries/Bluetooth/examples/BLEScanForEach - callback-based scan stream demo
  • libraries/Bluetooth/examples/BLECentralConnect - central connect/disconnect cycle
  • libraries/IEEE802154/examples/ - 802.15.4 config + passive scan examples
  • libraries/Watchdog/examples/FeedWatchdog - simple Watchdog.begin()/feed() compatibility check
  • libraries/XiaoNrf54L15/examples/AntennaSelect - Runtime antenna switching + radio profile info
  • Power/CpuFrequencyControl - CPU frequency monitor/control (Tools + optional runtime set)
  • Sense/IMUOrientation - onboard IMU accel/gyro stream
  • Sense/MicrophoneLevel - onboard DMIC buffer level monitor

Memory Usage

Example program storage usage:

  • GPIO/InterruptButton: ~52KB flash, ~19KB RAM
  • BLE menu-enabled example: ~180KB flash, ~39KB RAM
  • Full featured sketches: varies with selected radio/profile options

Architecture

This core consists of:

Core Components (cores/nrf54l15/)

  • Arduino.h - Main Arduino API definitions
  • cmsis.h - Cortex-M33 CMSIS core
  • nrf54l15.h - nRF54L15 peripheral definitions
  • wiring_*.c - Digital I/O, analog, timing, math, random
  • HardwareSerial.cpp - UART (Serial)
  • SPI.cpp - SPI
  • Wire.cpp - I2C
  • Print.cpp - Output stream
  • WString.h - String class (inline)
  • main.cpp - Entry point
  • core_install.c - Startup and exception handlers
  • syscalls.c - Newlib system call stubs
  • nrf54l15_linker_script.ld - Memory layout
  • startup_nrf54l15.s - Vector table (reference)

Variant (variants/xiao_nrf54l15/)

  • Pin definitions and mappings
  • Board-specific initialization

Known Limitations

  • No USB stack (CDC uses built-in debugger)
  • BLE capabilities are menu/profile dependent; validate with BLE examples for your selected controller/profile
  • BLE + 802.15.4 profile has high RAM usage; start from lighter sketches when enabling both radios
  • Thread/Mesh protocols not implemented

Contributing

Contributions are welcome! Please:

  1. Fork the repository
  2. Create a feature branch
  3. Make your changes
  4. Submit a pull request

License

Apache License 2.0 - See LICENSE file for details

Credits

  • Based on Nordic Semiconductor nRF54L15 reference materials
  • Inspired by the Arduino nRF52 core
  • CMSIS-CORE by ARM Ltd.

Links

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NRF54L15 Arduino core for XIAO nRF54L15 (Zephyr-based )

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v0.1.5 Latest
Feb 23, 2026
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