Arduino Nano Matter Pinout: GPIO, Thread, Matter, BLE and USB-C

The Arduino Nano Matter is a compact 45 × 18 mm wireless development board built around Silicon Labs’ MGM240SD22VNA module.

Its main purpose is low-power smart-home and IoT development using:

• Matter;
• Thread / OpenThread;
• Bluetooth Low Energy 5.3;
• Zigbee in the current Arduino Silicon Labs core;
• standard Arduino GPIO, ADC, DAC, SPI, I²C and UART.

The processor is a 32-bit Arm Cortex-M33 with 1.5 MB Flash and 256 kB RAM. The board operates at 3.3 V logic, includes a user RGB LED and button, and uses a USB-C connector connected through an onboard SAMD11 bridge for programming, serial and SWD debugging.

One important distinction is that Nano Matter is not a Wi-Fi board.

For a normal Matter-over-Thread project, the architecture is:

This guide covers the pinout first, then explains Thread, Matter, BLE, Arduino’s current Silicon Labs core, USB debugging, power options and the hardware details that matter when designing a real Nano Matter project.

Arduino Nano Matter Specifications

Feature	Arduino Nano Matter
Main module	Silicon Labs MGM240SD22VNA
Processor	32-bit Arm Cortex-M33
Maximum MCU frequency	78 MHz
Flash	1536 kB
RAM	256 kB
Operating logic voltage	3.3 V
Wireless radio	2.4 GHz IEEE 802.15.4 + Bluetooth LE
Matter transport	Thread
Bluetooth	Bluetooth LE 5.3
Zigbee	Supported by current Silicon Labs Arduino core
Exposed I/O	22 digital-capable positions
ADC	12-bit ADC hardware
DAC	Up to four 12-bit DAC channels
Hardware I²C	2 buses
Hardware SPI	2 buses
UART / USART	2 interfaces available in MCU
PWM	All exposed I/O are PWM-capable; maximum 5 simultaneous channels
USB connector	USB-C
USB bridge/debugger	ATSAMD11
Dimensions	45 × 18 mm

Complete Nano Matter Header Pinout

The current official Arduino pinout assigns the following functions to the Nano-style headers:

Arduino pin	Main default / alternate functions
D0	Digital I/O, PIN_SERIAL_TX1, SPI1 MOSI
D1	Digital I/O, PIN_SERIAL_RX1, SPI1 MISO
D2	Digital I/O, SPI1 SCK
D3	Digital I/O, SPI1 SS
D4	Digital I/O, I²C1 SDA
D5	Digital I/O, I²C1 SCL
D6	Digital I/O
D7	Digital I/O
D8	Digital I/O
D9	Digital I/O
D10	Digital I/O, SPI0 SS
D11	Digital I/O, SPI0 MOSI
D12	Digital I/O, SPI0 MISO
D13	Digital I/O, SPI0 SCK
A0 / D14	Analog input, digital I/O, DAC0
A1 / D15	Analog input, digital I/O, DAC2
A2 / D16	Analog input, digital I/O
A3 / D17	Analog input, digital I/O
A4 / D18	Analog input, digital I/O, I²C0 SDA
A5 / D19	Analog input, digital I/O, I²C0 SCL
A6 / D20	Analog input, digital I/O, DAC1
A7 / D21	Analog input, digital I/O, DAC3

Physical Nano Header Layout

With the USB-C connector at the top, the board keeps the familiar Nano dual-row format:

Nano Matter follows the newer Nano-family convention where D0 is the transmit pin and D1 is the receive pin.

3.3 V Logic: Do Not Feed GPIO with 5 V

Nano Matter is a 3.3 V logic board.

Do not directly connect a 5 V output to:

• D0-D13;
• A0-A7;
• AREF;
• other exposed MCU signals.

Use a suitable level shifter or resistor divider where required.

This is an important difference from classic Nano, Nano Every and Nano R4, which are 5 V platforms.

22 Digital-Capable I/O Positions

Arduino’s current datasheet states that all 22 exposed I/O positions can be used digitally.

That means the normal digital pins:

plus the analog-labelled pins:

can be used through the normal Arduino GPIO API where their active peripheral function is not required.

For example:

PWM on All Exposed I/O

One unusual Nano Matter feature is that the MCU can route PWM to all exposed I/O positions.

Arduino specifies:

So unlike classic AVR boards, PWM is not limited to a small fixed group of pins.

For ordinary use:

can be used on a supported free GPIO.

Why Only Five PWM Channels at Once?

The GPIO routing is flexible, but the number of active timer/comparator resources is finite.

So “every pin is PWM-capable” does not mean:

running simultaneously.

For a large LED or motor-control design, count actual simultaneous channels rather than just available header positions.

Analog Inputs

The pinout marks A0-A7 as the obvious analog header inputs:

The MGM240S contains a 12-bit ADC and Silicon Labs’ hardware is considerably more flexible than those eight printed analog labels suggest.

Arduino’s current user documentation notes that most exposed digital I/O can also be used as analog inputs, with specific exceptions depending on the pin/peripheral mapping.

For portable sketches, A0-A7 remain the clearest choices.

12-Bit ADC

A normal 12-bit conversion provides:

ideal codes.

Remember that 12-bit resolution does not automatically mean 12-bit absolute accuracy.

Real measurement performance depends on:

• reference accuracy;
• sensor impedance;
• noise;
• grounding;
• ADC gain and offset error.

DAC Outputs

The current official pinout marks four DAC-capable analog positions:

This gives Nano Matter considerably more native analog-output capability than many small Arduino boards.

The MGM240S supports up to 12-bit DAC operation.

DAC Is Different from PWM

A DAC creates an analog voltage level.

PWM instead creates a digital pulse train whose average value can be filtered.

Use a DAC where the receiving circuit genuinely needs an analog voltage rather than a duty-cycle signal.

Main I²C Bus

The default Arduino I²C bus uses:

and is labelled:

on the official pinout.

Normal Arduino code:

Second I²C Bus

A second hardware I²C mapping is exposed on:

This provides a useful extra bus for:

• duplicate-address sensors;
• separating fast and slow peripherals;
• isolating groups of devices;
• advanced board-specific applications.

The exact Arduino object/API used for the second bus depends on the Silicon Labs core version and library interface, so check the current core examples before hard-coding a generic Wire1 assumption from another Arduino architecture.

SPI0: Default SPI Bus

The familiar Nano SPI positions are:

These are labelled SPI0 on the official pinout.

Example:

SPI1: Second SPI Mapping

The second SPI peripheral is partially exposed through:

This mapping overlaps the default external serial pins on D0/D1.

So you cannot blindly use both interfaces simultaneously on those same physical pins.

UART / Serial Pins

The default external serial mapping is:

This ordering is easy to misread if you are accustomed to the classic Nano.

Always follow the Nano Matter pinout rather than assuming:

from older boards.

USB-C Is Not Native USB on the MGM240S

The Nano Matter’s USB-C connector is connected through an onboard ATSAMD11 board-controller/debugger.

The main MGM240S does not directly own the USB connector as a native USB application peripheral in the way an ESP32-S3 or RA4M1 board can.

The board-controller path provides:

• sketch upload;
• serial communication;
• SWD debugging;
• board programming support.

Debugging over USB

Arduino specifically advertises Nano Matter as supporting debugging without a separate external probe.

The SAMD11 bridge exposes the MGM240S SWD interface to development tools.

In the current Silicon Labs Arduino core, Nano Matter can use OpenOCD for:

• breakpoints;
• single stepping;
• variable inspection;
• debug sessions from Arduino IDE.

Matter, Thread and BLE Are Different Layers

This is the most important networking concept to understand.

A Matter-over-Thread accessory normally starts uncommissioned.

A phone or Matter controller uses BLE to discover and commission it, transfers the Thread network credentials, and then normal operational Matter traffic runs over Thread.

Nano Matter Has No Wi-Fi Radio

The MGM240S provides:

• IEEE 802.15.4;
• Bluetooth Low Energy;

but not conventional Wi-Fi.

That is different from ESP32-C6, which has Wi-Fi, BLE and IEEE 802.15.4 in one chip.

If you specifically want to compare the architectures, see our ESP32 Matter, Thread and Zigbee chip comparison.

You Need a Thread Border Router

A Thread Border Router connects the Thread IPv6 mesh to the normal home or building IP network.

The architecture is:

The Border Router and Matter controller are different roles, although one physical smart-home product may implement both.

For a detailed explanation of this network architecture, see our Matter over Thread and Home Assistant guide. The ESP32-C6 hardware is different, but the Matter/Thread/BLE networking concepts are the same.

Thread Is an IP Network

Thread is not simply another proprietary low-power radio protocol.

It carries IPv6 over IEEE 802.15.4.

This allows Matter devices to participate in an IP architecture while using a low-power mesh designed for IoT devices.

BLE 5.3

Nano Matter supports Bluetooth Low Energy 5.3.

BLE has two important roles:

• Matter commissioning;
• normal custom BLE applications.

The current Silicon Labs Arduino core allows BLE functionality to coexist with the Matter stack, although Matter commissioning has priority during initial setup.

BLE After Matter Commissioning

Current core documentation notes that custom BLE features can be used after Matter commissioning has completed.

This allows applications such as:

• local configuration;
• nearby diagnostics;
• BLE sensor interaction;
• custom mobile-app communication;

alongside Thread/Matter operation.

Current Arduino Protocol Stack Selection

The Silicon Labs Arduino platform currently provides selectable radio stacks under:

Options include:

• Matter;
• Zigbee;
• BLE using ArduinoBLE;
• BLE using the Silicon Labs API;
• None.

Choose the stack that matches the application.

Matter Stack Uses Significant Memory

The current core specifically notes that Matter is a relatively heavy protocol stack.

If you are using Nano Matter simply as a normal 3.3 V Arduino without wireless networking, selecting:

avoids linking a large radio stack and leaves considerably more Flash and RAM available to the application.

Matter Library

The Silicon Labs Arduino core bundles an Arduino Matter library.

It supports standard Matter device classes including:

• on/off and dimmable lights;
• outlets;
• temperature sensors;
• humidity sensors;
• contact sensors;
• occupancy sensors;
• door locks;
• fans;
• thermostats;
• air-quality sensors;
• window coverings;
• water valves;
• switches.

Matter Commissioning Flow

The normal workflow is:

1. Select the Matter protocol stack in Arduino IDE.
2. Flash the Nano Matter bootloader when required by the current setup workflow.
3. Upload a Matter example or sketch.
4. Open Serial Monitor.
5. Read the generated commissioning QR-code URL or manual pairing code.
6. Add a new Matter device in the smart-home app.
7. Pair over BLE.
8. The controller transfers Thread credentials.
9. Nano Matter joins the Thread mesh.
10. Normal Matter traffic runs over Thread.

Bootloader and Matter Network Credentials

The current Arduino Silicon Labs core performs a full chip erase when you explicitly burn the bootloader.

This is useful to know because Matter network keys and credentials are stored in non-volatile memory.

If you deliberately re-burn the bootloader, expect the device to require commissioning again.

Do Not Recommission After Every Normal Upload

Normal Matter network credentials persist through ordinary resets and sketch uploads.

You should not have to pair the board again every time you make a small application-code change.

Commissioning should normally be a one-time process unless:

• you decommission the device;
• you erase persistent storage;
• you burn the bootloader/full-chip erase;
• you change provisioning in a way that requires a fresh identity.

Current Core Also Supports Zigbee

Nano Matter is no longer limited to only Matter/Thread experiments in Arduino’s current software stack.

The current Silicon Labs core also offers a Zigbee stack.

This uses the same 2.4 GHz IEEE 802.15.4 radio hardware but a different network/application stack.

Choose:

when you want a Matter-compatible IP accessory.

Choose:

when you deliberately want a Zigbee device rather than Matter.

Secure Vault

The MGM240S platform includes Silicon Labs Secure Vault security features.

These are relevant to connected-device applications because Matter relies heavily on:

• device identity;
• cryptographic credentials;
• secure commissioning;
• encrypted sessions.

A development board makes those features accessible, but building a commercial certified Matter product involves manufacturing credentials and certification requirements beyond a normal Arduino sketch.

User RGB LED

Nano Matter includes an onboard RGB LED exposed through:

This is useful for indicating:

• commissioning mode;
• Thread connection;
• Matter online/offline state;
• sensor alarms;
• application status.

User Button

The board also includes a dedicated user push button available as:

This is convenient for:

• local control;
• factory-reset actions;
• commissioning triggers;
• demo applications.

For robust product-style firmware, use a long press rather than an accidental short press for destructive operations such as network reset or decommissioning.

Powering Nano Matter

The current Arduino datasheet supports several power methods:

• USB-C at 5 V;
• VIN from approximately 6 to 21 V;
• 5 V directly through the 5V header pin;
• 3.3 V direct power for specialised low-power configurations.

VIN

The current power architecture includes a buck converter and Arduino specifies:

as the external input range.

This is useful when Nano Matter is installed into a device with a higher-voltage supply.

5 V Pin

The 5 V header position can be used as a 5 V supply input.

When Nano Matter is USB powered, the official pinout also notes that this pin can output USB-derived 5 V.

Do not confuse the presence of a 5 V power rail with GPIO voltage: the GPIO remains 3.3 V logic.

Low-Power Configuration

Arduino specifically designed Nano Matter for low-power IoT applications.

The board includes solder jumpers that allow you to:

• disable the power LED;
• disconnect board power rails for specialised power configurations;
• configure the external ADC reference.

If battery life matters, onboard LEDs and the USB bridge can dominate current compared with the sleeping radio/MCU.

Measure the complete board rather than quoting only the MGM240S silicon sleep current.

Power LED Jumper

The underside includes a jumper that can be cut to disable the always-on power LED.

This is a simple but valuable modification for battery projects where a permanent indicator LED would waste more energy than the sleeping application itself.

AREF Jumper

The bottom-side pinout also documents a solder jumper for enabling the external analog-reference path.

Do not modify AREF circuitry casually; configure the ADC reference according to the current Arduino/Silicon Labs API and the MGM240S electrical limits.

Nano Matter vs Nano ESP32

Feature	Nano Matter	Nano ESP32
Main MCU	MGM240S / Cortex-M33	ESP32-S3 / dual-core LX7
Logic	3.3 V	3.3 V
Wi-Fi	No	Yes
Bluetooth LE	Yes	Yes
IEEE 802.15.4	Yes	No
Thread	Yes	No native 802.15.4 Thread radio
Matter over Thread	Yes	No
Zigbee	Yes in current core	No native 802.15.4 radio
PSRAM	No comparable external 8 MB PSRAM	8 MB
Native application USB	USB through SAMD11 bridge	Native ESP32-S3 USB

See our Arduino Nano ESP32 pinout guide for the Wi-Fi/BLE alternative.

When Nano Matter Is a Good Choice

Choose Nano Matter when you need:

• a native Thread endpoint;
• Matter-over-Thread development;
• Zigbee experimentation;
• Bluetooth LE alongside 802.15.4;
• low-power mesh networking;
• more analog flexibility than many small wireless boards;
• Arduino IDE plus Silicon Labs ecosystem access;
• built-in SWD debugging over USB.

When It Is Not the Best Choice

Nano Matter is less suitable when your application primarily needs:

• Wi-Fi networking;
• high-bandwidth web serving;
• large graphics buffers;
• camera workloads;
• large PSRAM;
• native USB device classes directly on the application MCU.

For those workloads, ESP32-S3 or another higher-memory wireless MCU may be more appropriate.

Quick Pin Reference

Best Practices

1. Remember that Nano Matter GPIO is 3.3 V, even though the board exposes a 5 V power pin.
2. Use A4/A5 for the default I²C bus and D10-D13 for default SPI.
3. Remember D0 is TX and D1 is RX on Nano Matter.
4. Do not assume all 22 PWM-capable pins can generate PWM simultaneously; Arduino specifies five simultaneous channels.
5. Select the correct radio protocol stack in Arduino IDE before building the application.
6. Use the Matter stack only when you actually need Matter; it consumes substantial Flash/RAM.
7. Expect Matter-over-Thread projects to require a Thread Border Router.
8. Keep BLE commissioning separate conceptually from normal Thread data transport.
9. Use the power-LED jumper and low-power supply options when battery life matters.
10. Use the onboard USB/SWD debugging support before reaching for an external probe.

Final Thoughts

Arduino Nano Matter is fundamentally different from a Nano ESP32 or classic Nano because its defining hardware feature is the integrated IEEE 802.15.4 radio.

That radio allows the board to operate directly as a Thread or Zigbee device, while Bluetooth LE handles commissioning and other local wireless functions.

The core pin mappings to remember are:

For connected projects, the networking model is equally important:

Once those layers are separated, Nano Matter becomes much easier to understand: it is a low-power, 3.3 V, Cortex-M33 Arduino designed around Thread/Matter and 802.15.4 rather than Wi-Fi.