XIAO nRF54LM20B

Overview

Seeed Studio XIAO nRF54LM20B is a compact, high-performance development board featuring the Nordic nRF54LM20B chip. This SoC integrates an ultra-low power multiprotocol 2.4 GHz radio and an MCU with a 128 MHz Arm(R) Cortex(R)-M33 processor. It offers 2 MB RRAM and 512 KB RAM.

The board features a built-in PMIC (Nordic NPM1300) with battery charging support, an RGB LED, an LSM6DS3TR-C 6-axis IMU, a USB 2.0 high-speed interface, NFCT, and an external SPI flash (PY25Q128HA, 128 Mbit). The XIAO form factor provides 28 pins (D0-D27) with support for GPIO, I2C, SPI, UART, ADC, PWM, and more.

Designed for exceptional ultra-low power consumption, it significantly extends battery life. Its robust radio supports Bluetooth(R), Matter, Thread, Zigbee, and a high-throughput 2.4 GHz proprietary mode. The board is ideal for compact, secure, and energy-efficient IoT solutions such as smart wearables, industrial sensors, and advanced human-machine interfaces.

Hardware

128 MHz Arm(R) Cortex(R)-M33 processor
2 MB RRAM (non-volatile memory)
512 KB RAM
Multiprotocol 2.4 GHz radio supporting Bluetooth Low Energy, 802.15.4-2020, and 2.4 GHz proprietary modes
Comprehensive set of peripherals including 14-bit ADC, high-speed serial interfaces, PDM/DMIC, and PWM
Built-in PMIC (Nordic NPM1300) with battery charging
RGB LED (red, blue, green)
LSM6DS3TR-C 6-axis IMU (accelerometer + gyroscope)
USB 2.0 high-speed interface
NFCT (Near Field Communication)
External SPI flash (PY25Q128HA, 128 Mbit)
28-pin XIAO connector (D0-D27)
Advanced security including TrustZone(R) isolation and cryptographic engine protection

For more information about the nRF54LM20B SoC and XIAO nRF54LM20B board, refer to these documents:

Supported Features

The xiao_nrf54lm20b board supports the hardware features listed below.

on-chip / on-board: Feature integrated in the SoC / present on the board.
2 / 2: Number of instances that are enabled / disabled.
Click on the label to see the first instance of this feature in the board/SoC DTS files.
vnd,foo: Compatible string for the Devicetree binding matching the feature.
Click on the link to view the binding documentation.

`xiao_nrf54lm20b/nrf54lm20b/cpuapp` target

On-target memory for this board target: 511 KiB of RAM, 2036 KiB of Flash.

Type	Location	Description	Compatible
CPU	on-chip	ARM Cortex-M33F CPU1	`arm,cortex-m33f`
ADC	on-chip	Nordic Semiconductor nRF family SAADC node1	`nordic,nrf-saadc`
ARM architecture	on-chip	Nordic UICR (User Information Configuration Registers)1	`nordic,nrf-uicr`
ARM architecture	on-chip	Nordic EGU (Event Generator Unit)2	`nordic,nrf-egu`
Audio	on-chip	Nordic PDM (Pulse Density Modulation interface)2	`nordic,nrf-pdm`
Clock control	on-chip	Generic fixed-rate clock provider4	`fixed-clock`
	on-chip	Nordic nRF low-frequency crystal oscillator (nRF54L series)1	`nordic,nrf54l-lfxo`
	on-chip	Nordic nRF high-frequency crystal oscillator (nRF54L series)1	`nordic,nrf54l-hfxo`
	on-chip	Nordic nRF clock control node1	`nordic,nrf-clock`
	on-chip	Nordic nRF XO clock control node1	`nordic,nrf-clock-xo`
	on-chip	Nordic nRF LFCLK clock control node1	`nordic,nrf-clock-lfclk`
	on-chip	Nordic nRF XO24M clock control node1	`nordic,nrf-clock-xo24m`
Comparator	on-chip	Nordic nRF COMP (analog COMParator)1	`nordic,nrf-comp`
Counter	on-chip	Nordic nRF timer node7	`nordic,nrf-timer`
Debug	on-chip	ARMv8 instrumentation trace macrocell1	`arm,armv8m-itm`
Flash controller	on-chip	Nordic RRAMC (Resistive random access memory controller)1	`nordic,rram-controller`
GPIO & Headers	on-chip	NRF5 GPIO3 1	`nordic,nrf-gpio`
	on-chip	NRF5 GPIOTE2	`nordic,nrf-gpiote`
	on-board	GPIO pins exposed on Seeeduino Xiao (and compatible devices) headers1	`seeed,xiao-gpio`
I2C	on-chip	Nordic nRF family TWIM (TWI master with EasyDMA)2 4	`nordic,nrf-twim`
I2C	on-board	I2C via GPIO bitbanging1	`gpio-i2c`
I2S	on-chip	Nordic TDM (Time division multiplexed audio interface)1	`nordic,nrf-tdm`
IEEE 802.15.4	on-chip	Nordic nRF IEEE 802.15.4 node1	`nordic,nrf-ieee802154`
Input	on-board	Group of GPIO-bound input keys1	`gpio-keys`
Interrupt controller	on-chip	ARMv8-M NVIC (Nested Vectored Interrupt Controller)1	`arm,v8m-nvic`
LED	on-board	Group of GPIO-controlled LEDs1	`gpio-leds`
	on-board	Group of PWM-controlled LEDs1	`pwm-leds`
	on-board	Nordic nPM1300 LED controller1	`nordic,npm1300-led`
Mailbox	on-chip	Nordic VEVIF (VPR Event Interface) - EVENT RX MODE1	`nordic,nrf-vevif-event-rx`
Mailbox	on-chip	Nordic VEVIF (VPR Event Interface) - TASK TX MODE1	`nordic,nrf-vevif-task-tx`
Multi-Function Device	on-board	Nordic nPM13001	`nordic,npm1300`
Miscellaneous	on-chip	Nordic FICR (Factory Information Configuration Registers)1	`nordic,nrf-ficr`
	on-chip	Nordic DPPIC (Distributed Programmable Peripheral Interconnect Controller)4	`nordic,nrf-dppic`
	on-chip	Nordic PPIB (Programmable Peripheral Interconnect Bridge)8	`nordic,nrf-ppib`
	on-chip	Nordic Axon1	`nordic,axon`
	on-chip	Nordic Memory Privilege Controller (MPC)1	`nordic,nrf-mpc`
MTD	on-board	Properties supporting Zephyr spi-nor flash driver (over the Zephyr SPI API) control of serial flash memories using the standard M25P80-based command set1	`jedec,spi-nor`
MTD	on-chip	Flash node1	`soc-nv-flash`
Networking	on-chip	Nordic nRF family RADIO peripheral1	`nordic,nrf-radio`
Networking	on-chip	Nordic nRF family NFCT (Near Field Communication Tag)1	`nordic,nrf-nfct-v2`
Pin control	on-chip	Nordic nRF family Pin Controller1	`nordic,nrf-pinctrl`
Power management	on-chip	Nordic nRF power control node1	`nordic,nrf-power`
PWM	on-chip	nRF PWM1 2	`nordic,nrf-pwm`
Regulator	on-chip	Nordic REGULATORS (voltage regulators control module) on nRF54L1	`nordic,nrf54l-regulators`
	on-chip	Nordic nRF5X regulator (fixed stage of the core supply)1	`nordic,nrf5x-regulator`
	on-chip	Nordic VBUS regulator for USB peripheral1	`nordic,vregusb-regulator`
	on-board	Nordic nPM1300 PMIC1	`nordic,npm1300-regulator`
Retained memory	on-chip	Nordic GPREGRET (General Purpose Register Retention) device1 1	`nordic,nrf-gpregret`
RISC-V architecture	on-chip	VPR coprocessor1	`nordic,nrf-vpr-coprocessor`
RNG	on-chip	Nordic nRF CRACEN CTR_DRBG based (Random Number Generator)1	`nordic,nrf-cracen-ctrdrbg`
Sensors	on-chip	Nordic nRF family TEMP node1	`nordic,nrf-temp`
	on-chip	Nordic nRF quadrature decoder (QDEC) node2	`nordic,nrf-qdec`
	on-board	STMicroelectronics LSM6DSL 6-axis accelerometer and gyrometer accessed through I2C bus1	`st,lsm6dsl`
	on-board	NPM1300 PMIC Charger1	`nordic,npm1300-charger`
Serial controller	on-chip	Nordic nRF family UARTE (UART with EasyDMA)2 5	`nordic,nrf-uarte`
SPI	on-chip	Nordic nRF family SPIM (SPI controller with EasyDMA)2 5	`nordic,nrf-spim`
SRAM	on-chip	Generic on-chip SRAM2	`mmio-sram`
Timer	on-chip	Nordic GRTC (Global RTC)1	`nordic,nrf-grtc`
Timer	on-chip	ARMv8-M System Tick1	`arm,armv8m-systick`
USB	on-chip	Nordic USBHS Type 2 PHY configuration1	`nordic,nrf-usbhs-phy-type2`
	on-chip	Nordic wrapper for USB controller and PHY hardware1	`nordic,nrf-usbhs-wrapper`
	on-chip	DesignWare OTG USB 2.0 controller1	`snps,dwc2`
	on-chip	Nordic USB PD Charging-Type Detector1	`nordic,nrf-usbhs-bc12`
Watchdog	on-chip	Nordic nRF family WDT (Watchdog Timer)2	`nordic,nrf-wdt`

Connections and IOs

In the following table, the column Name contains Pin names. For example, P1_0 means Pin number 0 on PORT1, as used in the board’s datasheets and manuals.

Name	Function	Usage
P1_22	GPIO	LED1 (Red)
P1_23	GPIO	LED0 (Blue)
P1_24	GPIO	LED2 (Green)
P0_9	GPIO	Button 0
P1_11	USART20_TX	UART20 TX (test pad)
P1_10	USART20_RX	UART20 RX (test pad)
P1_8	USART21_TX	XIAO Serial TX
P1_9	USART21_RX	XIAO Serial RX
P1_3	TWIM22_SDA	XIAO I2C SDA
P1_7	TWIM22_SCL	XIAO I2C SCL
P1_4	SPIM23_SCK	XIAO SPI SCK
P1_6	SPIM23_MOSI	XIAO SPI MOSI
P1_5	SPIM23_MISO	XIAO SPI MISO
P0_8	TWIM30_SDA	IMU I2C SDA
P0_7	TWIM30_SCL	IMU I2C SCL
P1_0	GPIO	XIAO D0
P1_31	GPIO	XIAO D1
P1_30	GPIO	XIAO D2
P1_29	GPIO	XIAO D3
P1_3	GPIO	XIAO D4
P1_7	GPIO	XIAO D5
P1_8	GPIO	XIAO D6
P1_9	GPIO	XIAO D7
P1_4	GPIO	XIAO D8
P1_5	GPIO	XIAO D9
P1_6	GPIO	XIAO D10
P1_18	GPIO	PMIC I2C SDA
P1_17	GPIO	PMIC I2C SCL
P1_13	PDM20_CLK	DMIC Clock
P1_14	PDM20_DIN	DMIC Data
P2_1	SPIM00_SCK	External SPI Flash SCK
P2_2	SPIM00_MOSI	External SPI Flash MOSI
P2_4	SPIM00_MISO	External SPI Flash MISO

The board has a single USB-C connector, wired to the SoC’s USB 2.0 high-speed controller. The console is available over USB CDC ACM on this connector.

Programming and Debugging

The xiao_nrf54lm20b board supports the runners and associated west commands listed below.

	flash	debug	debugserver	rtt	reset	attach
jlink	✅	✅ (default)	✅	✅	✅	✅
nrfutil	✅ (default)

Bootloader and firmware updates

The board ships from the factory with an MCUboot firmware-updater bootloader in the first 24 KiB of RRAM. Applications are therefore linked by default into the bootloader’s application slot at 0x6000 (CONFIG_BOOTLOADER_MCUBOOT defaults to y), and the USB CDC ACM console described below is provided by the application; the bootloader itself has no console.

The factory bootloader verifies Ed25519 image signatures (PURE format) against a key provisioned in the board’s KMU, so applications flashed to the application slot must be signed accordingly; see the XIAO nRF54LM20B Wiki for signing details and factory firmware updates.

To update the application over USB, keep Button 0 pressed while powering or resetting the board: the bootloader then runs its slot1 USB loader, which accepts an MCUmgr image upload over the USB CDC ACM port.

Flashing

Connect the XIAO nRF54LM20B board to your host computer using the USB port. A USB CDC ACM serial port should appear on the host, that can be used to view logs from the flashed application.

Here is an example for the Hello World application.

# From the root of the zephyr repository
west build -b xiao_nrf54lm20b/nrf54lm20b/cpuapp samples/hello_world
west flash

Open a serial terminal (minicom, putty, etc.) connecting to the USB CDC ACM serial port.

Reset the board and you should see the following message in the terminal:

Hello World! xiao_nrf54lm20b/nrf54lm20b/cpuapp