Arduino Nano 33 IoT

What is the Arduino Nano 33 IoT?

The Arduino Nano 33 IoT is a tiny Wi-Fi and Bluetooth microcontroller board in the classic 45 × 18 mm Nano footprint. A 32-bit SAMD21G18A runs your sketch, while a u-blox NINA-W102 module handles the radio — so you can put sensors on the internet, talk to a phone over BLE or send data to the cloud from a board smaller than a stick of gum.

The “33” in the name means 3.3 V: unlike the original Arduino Nano, every pin works at 3.3 V logic. The “IoT” part comes from three extras packed onto the board: the Wi-Fi/BLE module, a 6-axis LSM6DS3 IMU (accelerometer + gyroscope) and an ATECC608A secure element for encrypted cloud connections.

A map of the Nano 33 IoT: the SAMD21 runs your code, the NINA-W102 does Wi-Fi/BLE, and the IMU and crypto chip sit on its I2C bus.

How the Nano 33 IoT Is Wired Inside

The Nano 33 IoT is really a small network of chips. The SAMD21 sits in the middle and talks to every other part over a different link.

System view: USB to the PC, SPI to the radio, I2C to the IMU, crypto chip and your own sensors.

The Brain: SAMD21G18A (ARM Cortex-M0+)

The Microchip SAMD21G18A is a 32-bit ARM chip. It is a big step up from the 8-bit ATmega328P on the Uno: 3× the clock, 8× the flash and 16× the RAM.

Inside the SAMD21: a Cortex-M0+ CPU, 256 KB flash / 32 KB SRAM, DMA and a rich set of peripherals on two internal buses.

• Flash (256 KB) — holds your program. About 8 KB is taken by the USB bootloader.
• SRAM (32 KB) — room for Wi-Fi buffers, JSON strings and sensor arrays that would never fit on an Uno.
• No EEPROM — to keep settings across power cycles, save them to flash with the FlashStorage library.
• 6 SERCOMs — flexible serial blocks. Each can become a UART, SPI or I2C port, so you can add extra buses on other pins.
• 12-bit ADC and 10-bit DAC — finer analog readings and a real analog output on A0.
• DMA, RTC and 32.768 kHz crystal — move data without the CPU and keep accurate time for low-power logging.

Full Arduino Nano 33 IoT Pinout

Here is the complete pinout. Every pin shows its Arduino number, the SAMD21 port pin (PAxx / PBxx) and its alternate functions: PWM, analog, DAC, SPI, I2C, UART or power.

The full Nano 33 IoT pinout (USB at the top): power and analog pins on the left, digital pins on the right, colour-coded by function.

Want a quicker view? This map groups the pins by what they do:

Quick pin map: SPI, digital/PWM and Serial1 on one header; analog, I2C and power on the other.

Every Pin Explained

Now let's go through each group of pins and what it does. Remember: every signal pin is 3.3 V and can supply only about 7 mA.

Digital pins (D0–D13)

14 general-purpose pins that read or write HIGH (3.3 V) or LOW (0 V) with pinMode(), digitalWrite() and digitalRead(). Internal pull-up and pull-down resistors are available (INPUT_PULLUP, INPUT_PULLDOWN). Some pins have special jobs:

Analog pins (A0–A7)

8 inputs connected to a 12-bit ADC. By default analogRead() returns 0–1023 (10-bit, Uno-compatible). Call analogReadResolution(12) to get the full 0–4095 over 0–3.3 V. All of them can also be used as digital pins D14–D21.

• A0 = DAC0 — a real 10-bit digital-to-analog converter (true analog voltage, not PWM).
• A4 = SDA and A5 = SCL — the I2C bus, already shared with the on-board IMU and crypto chip and fitted with pull-up resistors. Avoid using A4/A5 as plain analog inputs.
• A6 and A7 — unlike the classic Nano, these also work as digital pins.
• AREF — optional external reference voltage for the ADC (never above 3.3 V).

Power & control pins

3.3 V Logic — the #1 Rule

The Nano 33 IoT is not 5 V tolerant. Connecting a 5 V signal straight to a pin can permanently damage the SAMD21. Here are two safe ways to mix 3.3 V and 5 V parts.

A: a voltage divider for one-way 5 V signals into the board. B: a level shifter for two-way buses such as I2C.

Powering the Nano 33 IoT

There are two ways to power the board: micro-USB (5 V) or the VIN pin (5–21 V). Both feed a switching buck converter that makes a clean 3.3 V rail for every chip.

Power paths: USB or VIN → buck → 3.3 V. The 5V pin only gets USB power after you bridge the VUSB jumper.

• Why a buck converter? A linear regulator would turn most of 12 V into heat. The switching buck is far more efficient, which matters for battery projects and Wi-Fi current peaks.
• Wi-Fi current — the radio draws short bursts of current when transmitting. Use a good USB cable and a supply with some headroom.
• 5 V modules — if a sensor needs 5 V power, bridge VUSB and power from USB, or use an external 5 V supply with a shared GND and level-shift its signals.

PWM, ADC and the True DAC

The SAMD21 gives the Nano 33 IoT better analog features than an AVR board: 11 PWM pins, a 12-bit ADC and a real DAC on A0.

PWM fakes an analog level by switching; the ADC measures voltage in steps; the DAC outputs a real voltage.

At 12 bits each ADC step is 3.3 V / 4096 ≈ 0.8 mV. For a potentiometer, connect its ends to 3V3 and GND (not 5 V), with the wiper on an analog pin.

Communication: USB Serial, UART, SPI & I2C

Four ways to talk to the world — and thanks to native USB, the hardware UART stays free for your own devices.

Serial = USB, Serial1 = D0/D1, SPI on D10–D13, I2C (Wire) on A4/A5.

Wi-Fi with the NINA-W102 and WiFiNINA

The SAMD21 never touches the radio itself. It sends commands over SPI to the NINA-W102, which runs Wi-Fi firmware on its own ESP32 and joins your 2.4 GHz network.

From sketch to cloud: WiFiNINA → SPI → NINA-W102 → router → internet.

• Library: install WiFiNINA. It provides WiFiClient, WiFiServer, WiFiUDP and WiFiSSLClient for HTTPS/TLS.
• Networks: 802.11 b/g/n on 2.4 GHz only — a 5 GHz-only router won't be found.
• Firmware: keep the NINA firmware up to date with the IDE's firmware updater tool so new TLS certificates and fixes are included.
• Cloud: the board works with Arduino IoT Cloud, MQTT brokers (e.g. with ArduinoMqttClient) and plain HTTP APIs.

Bluetooth Low Energy (BLE)

The same NINA module also speaks Bluetooth. With the ArduinoBLE library the board becomes a BLE peripheral that a phone app (the central) can read, write and subscribe to.

BLE in one picture: the board advertises a service; each value is a characteristic the phone can read, write or be notified about.

The Built-in IMU and Crypto Chip

Two extra chips make the Nano 33 IoT useful straight out of the box: an LSM6DS3 motion sensor and an ATECC608A secure element.

The LSM6DS3 measures acceleration (g) and rotation (degrees per second) on three axes.

How Code Gets onto the Nano 33 IoT

Install the right board package once, and uploading works just like any Arduino — but over the SAMD21's native USB.

Upload flow, and the rescue trick: double-tap RESET and the L LED pulses to show bootloader mode.

1. Arduino IDE → Tools → Board → Boards Manager → install Arduino SAMD Boards (32-bits ARM Cortex-M0+).
2. Select Arduino Nano 33 IoT and its port (COM on Windows, /dev/ttyACM* on Linux).
3. Click Upload. The port may briefly change as the board resets into the bootloader — that's normal.
4. If a crashed sketch hides the port, double-tap RESET, pick the new port and upload again.

Code Examples

Short, copy-paste sketches for each feature of the board.

1. Blink the on-board LED

void setup() {
  pinMode(LED_BUILTIN, OUTPUT);       // D13, orange "L" LED
}
void loop() {
  digitalWrite(LED_BUILTIN, HIGH);
  delay(500);
  digitalWrite(LED_BUILTIN, LOW);
  delay(500);
}

2. Connect to Wi-Fi and print the IP address

#include <WiFiNINA.h>
char ssid[] = "MySSID";
char pass[] = "password";

void setup() {
  Serial.begin(115200);
  while (!Serial);                    // wait for the Serial Monitor (remove on battery)
  while (WiFi.begin(ssid, pass) != WL_CONNECTED) {
    Serial.println("Connecting...");
    delay(2000);
  }
  Serial.print("IP: ");   Serial.println(WiFi.localIP());
  Serial.print("RSSI: "); Serial.println(WiFi.RSSI());  // signal in dBm
}
void loop() {}

3. Read the IMU (accelerometer)

#include <Arduino_LSM6DS3.h>

void setup() {
  Serial.begin(115200);
  if (!IMU.begin()) { Serial.println("IMU not found"); while (1); }
}
void loop() {
  float x, y, z;
  if (IMU.accelerationAvailable()) {
    IMU.readAcceleration(x, y, z);     // values in g
    Serial.print(x); Serial.print('\t');
    Serial.print(y); Serial.print('\t');
    Serial.println(z);
  }
  delay(100);
}

4. 12-bit ADC in, true DAC out

void setup() {
  Serial.begin(115200);
  analogReadResolution(12);          // 0..4095
  analogWriteResolution(10);         // DAC 0..1023
}
void loop() {
  int raw = analogRead(A1);            // pot wiper on A1 (ends on 3V3 and GND)
  float volts = raw * 3.3 / 4095.0;
  Serial.println(volts, 3);
  analogWrite(A0, raw >> 2);           // same level out of the DAC on A0
  delay(200);
}

Beginner IoT Mini-Projects

Put it all together. Each project needs only a few cheap parts, and the code is complete — upload and go.

Wiring for projects 1 and 2 — LED + 220 Ω on D2 (≈ 6 mA at 3.3 V), push button on D3 to GND.

#include <WiFiNINA.h>
char ssid[] = "MySSID", pass[] = "password";
WiFiServer server(80);

void setup() {
  pinMode(2, OUTPUT);
  Serial.begin(115200);
  while (WiFi.begin(ssid, pass) != WL_CONNECTED) delay(2000);
  server.begin();
  Serial.println(WiFi.localIP());      // open this address in a browser
}
void loop() {
  WiFiClient client = server.available();
  if (!client) return;
  String req = client.readStringUntil('\r');   // e.g. "GET /on HTTP/1.1"
  if (req.indexOf("GET /on")  >= 0) digitalWrite(2, HIGH);
  if (req.indexOf("GET /off") >= 0) digitalWrite(2, LOW);
  client.println("HTTP/1.1 200 OK");
  client.println("Content-Type: text/html");
  client.println();
  client.println("<h1>Nano 33 IoT</h1><a href='/on'>ON</a> | <a href='/off'>OFF</a>");
  delay(1);
  client.stop();
}

#include <Arduino_LSM6DS3.h>

void setup() {
  pinMode(2, OUTPUT);
  if (!IMU.begin()) while (1);
}
void loop() {
  float x, y, z;
  if (IMU.accelerationAvailable()) {
    IMU.readAcceleration(x, y, z);
    bool tilted = (z < 0.7);        // cos(45°) ≈ 0.707 g
    digitalWrite(2, tilted ? HIGH : LOW);
  }
}

#include <ArduinoBLE.h>
BLEService ledService("19B10000-E8F2-537E-4F6C-D104768A1214");
BLEByteCharacteristic switchChar("19B10001-E8F2-537E-4F6C-D104768A1214", BLERead | BLEWrite);

void setup() {
  pinMode(LED_BUILTIN, OUTPUT);
  if (!BLE.begin()) while (1);
  BLE.setLocalName("Nano33IoT");
  BLE.setAdvertisedService(ledService);
  ledService.addCharacteristic(switchChar);
  BLE.addService(ledService);
  switchChar.writeValue(0);
  BLE.advertise();
}
void loop() {
  BLEDevice central = BLE.central();
  while (central && central.connected()) {
    if (switchChar.written())
      digitalWrite(LED_BUILTIN, switchChar.value() ? HIGH : LOW);
  }
}

int count = 0;
bool last = HIGH;

void setup() {
  pinMode(3, INPUT_PULLUP);
  Serial.begin(115200);
}
void loop() {
  bool now = digitalRead(3);
  if (last == HIGH && now == LOW) {   // falling edge = press
    count++;
    Serial.print("Presses: "); Serial.println(count);
    delay(30);                          // crude debounce
  }
  last = now;
}

Nano 33 IoT vs Other Nano Boards

All of these boards share the same 45 × 18 mm footprint, so choosing between them is about wireless, speed and logic voltage.

Nano 33 IoT vs Nano, Nano 33 BLE and Nano ESP32.

• Pick the Nano 33 IoT for Wi-Fi + BLE with the simple Arduino API, a built-in IMU and secure cloud connections.
• Pick the classic Nano when you need 5 V logic for older shields and modules.
• Pick the Nano 33 BLE for low-power Bluetooth projects and TinyML (more RAM, 9-axis IMU, no Wi-Fi).
• Pick an ESP32 board when you need raw speed and lots of memory for heavy Wi-Fi apps.

Specifications

The Arduino Nano 33 IoT at a glance.

Key numbers for the Nano 33 IoT: MCU, memory, wireless, sensors, voltage, pins and size.

Key Terms — Glossary

Related Topics & Common Searches

The Nano 33 IoT connects to a whole world of parts. Explore these Power4All guides:

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Frequently Asked Questions

Quick answers to the questions people ask most about the Arduino Nano 33 IoT.

Conclusion & Key Takeaways

The Arduino Nano 33 IoT gives you a 32-bit ARM chip, Wi-Fi, Bluetooth, a motion sensor and hardware security in the tiny Nano footprint. Respect the 3.3 V limit and it's one of the easiest ways to put a project on the internet.

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