nRF54L Arduino Framework (s145 SoftDevice)

Arduino BSP for Nordic Semiconductor nRF54L05 / nRF54L10 / nRF54L15 with the s145 SoftDevice 9.0.0. Derived from Adafruit_nRF52_Arduino and reworked for nRF54L peripherals.

PlatformIO only. This framework is consumed exclusively through the companion PlatformIO platform meshtastic/platform-nordicnrf54. There is no platform.txt, boards.txt, or Arduino IDE / Board Manager support, and there are no plans to add any. Use PlatformIO.

Supported boards

Variant	MCU	Source
xiao_nrf54l15	nRF54L15	Seeed Studio XIAO nRF54L15
xiao_nrf54l15_sense	nRF54L15	Seeed Studio XIAO nRF54L15 Sense
nrf54l15dk	nRF54L15	Nordic nRF54L15-DK
nrf54l10dk	nRF54L10	Nordic nRF54L15-DK with L10 silicon
nrf54l05dk	nRF54L05	Nordic nRF54L15-DK with L05 silicon

Board JSONs and upload tooling live in the PlatformIO platform repo.

Installation

; platformio.ini
[env:xiao_nrf54l15]
platform = https://github.com/meshtastic/platform-nordicnrf54.git
framework = arduino
board = xiao_nrf54l15

The platform pulls this framework, the nRF54_Bootloader hex package, and toolchains automatically on first build.

What's in here

• s145 SoftDevice 9.0.0 API headers and merge-time hex (cores/nRF5/nordic/softdevice/s145_nrf54l_9.0.0_API/, bootloader/s145/9.0.0/*_softdevice.hex)
• nRF54L MDK headers for L05/L10/L15 application + flpr targets (cores/nRF5/nordic/nrfx/mdk/)
• FreeRTOS port running off the GRTC peripheral (nRF54L has no SysTick); see cores/nRF5/freertos/portable/{GCC,CMSIS}/nrf54l/
• SoftDevice interrupt forwarding (cores/nRF5/nordic/sd_isr.S): s145 has no MBR, the application owns the vector table and hands the SoftDevice its interrupts and SVCs
• Linker scripts for all three chips that reserve 28 KB at the top of the application FLASH region for InternalFS (cores/nRF5/linker/)
• nrf54l_compat.h force-included by the platform's build script. Aliases nRF52 peripheral names to their nRF54L equivalents (NRF_PWM0..2 → NRF_PWM20..22, NRF_TWIM0/1 → NRF_TWIM20/22, NRF_SPIM0/2 → NRF_SPIM00/21, NRF_UARTE0/1 → NRF_UARTE00/20, NRF_GPIOTE → NRF_GPIOTE20, etc.) so most of the Adafruit core code compiles unmodified
• wiring_analog_nRF54L.c — dedicated SAADC implementation for nRF54L (different reference voltage, multiplier gains, microsecond TACQ, byte-count MAXCNT, structured PSELP)
• InternalFileSystem (LittleFS) wired against __flash_arduino_start / __flash_arduino_end linker symbols, so no per-chip ifdefs in C++ code
• Bluefruit54Lib with HID detached from TinyUSB, plus BANDWIDTH-aware data-length-update reply
• Library wrappers for SPI, Wire (with per-variant TWIM instance override), Servo, SoftwareSerial, RotaryEncoder, PDM, nRF54Crypto (CRACEN RNG plus tinycrypt ECDH, replacing nRF52840's CryptoCell)

Memory map

s145 ships without an MBR. The DFU bootloader owns RRAM 0x0 and the reset vector, the application starts at 0x8000, and the SoftDevice sits at the top of RRAM.

Chip	Bootloader	App FLASH	InternalFS (LittleFS)	DFU settings	SoftDevice
nRF54L05	0x0 – 0x8000	0x8000 – 0x47000	0x47000 – 0x4E000	0x4F000	0x58C00
nRF54L10	0x0 – 0x8000	0x8000 – 0xC7000	0xC7000 – 0xCE000	0xCF000	0xD8C00
nRF54L15	0x0 – 0x8000	0x8000 – 0x147000	0x147000 – 0x14E000	0x14F000	0x158C00

RAM: 0x20000000 – 0x20004800 belongs to the SoftDevice, the application runs from 0x20004800 to 0x2003FF80; the last 128 bytes hold the bootloader's BLE peer data and double-reset marker. The layout matches the nRF54_Bootloader linker scripts.

Limitations

• No USB. nRF54L has no USB peripheral. The Adafruit_TinyUSB_Arduino submodule has been removed. Sketches that need a host serial channel on the XIAO variants get it through the on-board SAMD11 USB bridge over UART, not over native CDC.
• No Adafruit_nRFCrypto. nRF52840's CryptoCell CC310 is replaced by CRACEN on nRF54L. Use nRF54Crypto/ instead.
• HardwarePWM and Wire share peripheral fabric on XIAO. On the XIAO variants, Wire is routed to TWIM22 (a dedicated TWI controller) via a per-variant override so it doesn't compete with SPI/UARTE on the SERIAL00/SERIAL20 fabric. See variants/xiao_nrf54l15/variant.h.
• PIN pairing uses LE Secure Connections. s145 rates legacy passkey pairing as unauthenticated (security level 2); characteristics with MITM permissions need an LESC bond. The key agreement runs on CRACEN/tinycrypt via nRF54Crypto.

Credits

• Adafruit_nRF52_Arduino — the codebase this fork descends from. Core class layout, Bluefruit54Lib, Wire, SPI, FreeRTOS integration, InternalFS.
• NRF54L15-Clean-Arduino-core — sibling project by lolren. Bare-metal (no SoftDevice); we share API surface and have ported a handful of fixes (Print compat, BANDWIDTH cap behavior, XIAO TWIM22 routing, SAADC MAXCNT-in-bytes).
• Arduino-nRF5 by Sandeep Mistry — the original Arduino-style nRF52 BSP that Adafruit's was forked from.
• FreeRTOS, LittleFS, nrfx.

License

Mixed BSD-3-Clause / MIT / LGPL-2.1 depending on file provenance. See individual headers and LICENSE.