Arduino Nano Reference
The ATmega328P-based board — electrically identical to the Uno, in a compact breadboard-friendly DIP form factor.
Pin names
| Pin ID | Label | Signal | Notes |
|---|---|---|---|
0 | D0 / RX | USART | Serial receive |
1 | D1 / TX | USART | Serial transmit |
2 | D2 | Digital | External interrupt INT0 |
3 | D3 | PWM | External interrupt INT1, analogWrite() |
4 | D4 | Digital | |
5 | D5 | PWM | analogWrite() |
6 | D6 | PWM | analogWrite() |
7 | D7 | Digital | |
8 | D8 | Digital | |
9 | D9 | PWM | analogWrite() |
10 | D10 / SS | SPI | SPI slave select, analogWrite() |
11 | D11 / MOSI | PWM / SPI | SPI data out, analogWrite() |
12 | D12 / MISO | SPI | SPI data in |
13 | D13 / SCK | SPI | SPI clock, built-in LED |
GND | GND | Power | Ground (multiple pins) |
RESET | RESET | — | Pull LOW to reset the board |
AREF | AREF | — | Analog reference voltage |
3.3V | 3.3V | Power | 3.3 V output |
5V | 5V | Power | 5 V output |
VIN | VIN | Power | External power input (7–12 V) |
A0–A3 | A0–A3 | Analog | analogRead(), 10-bit (0–1023) |
A4 | A4 / SDA | I²C | I²C data |
A5 | A5 / SCL | I²C | I²C clock |
A6 / A7 | A6, A7 | Analog | Analog input only — not usable as digital I/O |
Quick reference
| Capability | Pins |
|---|---|
| Digital I/O | D0–D13 (14 pins) |
| Analog input | A0–A7 (8 pins, 10-bit; A6/A7 analog-only) |
| PWM output | D3, D5, D6, D9, D10, D11 |
| SPI | D10 (SS), D11 (MOSI), D12 (MISO), D13 (SCK) |
| I²C | A4 (SDA), A5 (SCL) |
| USART | D0 (RX), D1 (TX) |
| Operating voltage | 5 V |
| Clock speed | 16 MHz |
Usage
void setup() {
pinMode(13, OUTPUT);
Serial.begin(9600);
}
void loop() {
digitalWrite(13, HIGH);
int val = analogRead(A0);
analogWrite(9, 128);
Serial.println(val);
delay(500);
}Code written for an Uno runs unmodified on a Nano — the two share the same ATmega328P core, pinout, and Arduino API. Reach for the Nano when board size matters (e.g. permanent breadboard projects) rather than for any functional difference.
See also
- Arduino Uno — same core and pinout, larger form factor
- Arduino Mega — same programming model with far more I/O
- ESP32 DevKit V1 — WiFi/Bluetooth-capable alternative with a different pin layout