Overview:

The Arduino Nano is a compact, breadboard?friendly microcontroller board from Arduino. It’s designed to give much of the power of an Arduino Uno in a much smaller form factor.

Originally released around 2008, the classic Nano uses the ATmega328P microcontroller. There are newer variants like the Nano Every, Nano R4 etc.

 Technical Specifications (Classic ATmega328P Nano)

Parameter

Value

MCU

ATmega328P (8?bit AVR)

Clock Speed

16 MHz

Operating Voltage (logic)

5 V

Input Voltage (recommended)

7?12 V (if powering via Vin)

Max Input Voltage (limits)

~6?20 V depending on the version / components

Digital I/O Pins

14 pins (D0?D13)

PWM Digital Pins

6 pins (D3, D5, D6, D9, D10, D11)

Analog Input Pins

8 pins (A0?A7)

Flash Memory

32 KB (of which ~2 KB used by bootloader)

SRAM

2 KB

EEPROM

1 KB

Maximum DC Current per I/O Pin

40 mA (absolute max)

Dimensions

~45 mm × 18 mm

 

 Pinout and Key Functionalities

Here’s how the pins are arranged and what they can do:

Pin / Group

Function / Notes

Power Pins

* Vin – external input (7?12 V) when not using USB.
* 5V – regulated output (or input if the board is powered by a regulated supply).
* 3V3 – 3.3 V output.
* GND – ground pins.
* AREF – reference voltage for analog inputs.
* Reset – to reset the MCU.

Digital I/O (D0?D13)

Can be used for general purpose digital input/output.
* D0 = RX, D1 = TX (for serial communication)
* D2, D3 can be used for external interrupts
* Some pins double as PWM outputs.
* Pins D10?D13 also support SPI interface: D11 = MOSI, D12 = MISO, D13 = SCK, D10 usually used as SS.

Analog Inputs (A0?A7)

Used to read analog voltages, via the ADC on the MCU. A4/A5 are also used for I2C (SDA/SCL).
Note: A6 and A7 are analog only — they cannot be used for digital I/O.

Communication Interfaces

* Serial (UART) – using D0,RX and D1,TX.
* I2C – using A4 (SDA) and A5 (SCL).
* SPI – using digital pins D10?D13.
* Some variants may support additional communication depending on microcontroller.

 

 Things to Keep in Mind / Limitations

While each digital I/O pin can source or sink up to ~40 mA, staying near the maximum is risky. Best practice is to stay well below this (e.g. 20?25 mA) to avoid overheating or damaging the MCU.

The AREF pin should be handled carefully; using it incorrectly could damage analog inputs.

The Vin pin expects unregulated input; input voltage higher than what’s safe for the onboard voltage regulator (plus heat dissipation) can cause issues.

Some “Nano” board variants (Nano Every, Nano R4, Nano 33 IoT etc.) have different microcontrollers, operating voltages (many are 3.3 V), USB connectors, or extra features. So always check which variant you have.