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Arduino Nano Pinout

Arduino Nano (ATmega328P) · 30-pin board, two rows of 15, 0.6 in apart

The Nano is an Uno's ATmega328P on a 30-pin board that plugs into a breadboard or a 0.6 in socket: the same I/O as the Uno, plus two analog-only inputs, A6 and A7.

Checked against the KiCad library and datasheet on

Arduino Nano (ATmega328P) pinout: KiCad footprint Module:Arduino_Nano seen from the top, beside the KiCad library symbol MCU_Module:Arduino_Nano_v3.x with every pin number and name
KiCad numbers the Nano's pins 1 to 30 round the board, starting at D1/TX with the USB end at the bottom. The table uses those numbers, with the board's own labels beside them. Exported from the KiCad 9 libraries (MCU_Module:Arduino_Nano_v3.x, Module:Arduino_Nano). Open full size

Pin by pin

PinNameFunction
1D1 / TXUART transmit, also wired to the USB-serial chip
2D0 / RXUART receive, also wired to the USB-serial chip
3RESETActive-low reset (same net as pin 28)
4GNDGround
5D2External interrupt INT0
6D3 ~PWM, external interrupt INT1
7D4Digital I/O
8D5 ~PWM
9D6 ~PWM
10D7Digital I/O
11D8Digital I/O
12D9 ~PWM
13D10 ~PWM, SPI SS
14D11 ~PWM, SPI MOSI
15D12SPI MISO
16D13SPI SCK, on-board LED
173V33.3 V output, small current (see below)
18AREFAnalog reference input
19A0Analog in; digital I/O 14
20A1Analog in; digital I/O 15
21A2Analog in; digital I/O 16
22A3Analog in; digital I/O 17
23A4Analog in, I²C SDA
24A5Analog in, I²C SCL
25A6Analog input only
26A7Analog input only
27+5V5 V out when powered from USB or VIN; 5 V in otherwise
28RESETActive-low reset
29GNDGround
30VINInput to the on-board regulator, 7–12 V recommended

Things that catch people out

  • A6 and A7 reach the ADC but no I/O port, so digitalRead and pinMode do nothing on them.
  • D0 and D1 are shared with the USB-serial chip. Anything connected to them can block uploads.
  • Nanos made before 2018, and many clones (often with a CH340 USB chip), still have the old bootloader. If uploads time out, pick "ATmega328P (Old Bootloader)" as the processor in the Arduino IDE.
  • The 3V3 pin is weak: on the original Nano it is the FT232RL's 3.3 V output, about 50 mA, and on clones it can be less. Do not run a radio module from it.
  • 40 mA per I/O pin is the absolute maximum; Arduino recommends 20 mA.

Putting the Arduino Nano (ATmega328P) on a PCB

  • Socketing a Nano: two 1×15 rows at 2.54 mm pitch, 15.24 mm (0.6 in) apart, 1.0 mm holes, as in KiCad's Module:Arduino_Nano.
  • Put the USB end at the edge of your board so the cable still fits once the Nano is plugged in.
  • Power it through VIN or +5V, not both from different supplies.

Designing a board around it? Read From an Arduino prototype to a custom PCB.

Common questions

What is the difference between the Arduino Nano and Uno pinout?
Same microcontroller and the same D0 to D13 and A0 to A5. The Nano adds A6 and A7 (analog only), drops the Uno's IOREF and separate SDA/SCL header, and puts everything on two breadboard-friendly rows.
Which Arduino Nano pins are PWM?
D3, D5, D6, D9, D10 and D11.
Which Nano pins are I²C and SPI?
I²C is A4 (SDA) and A5 (SCL). SPI is D10 (SS), D11 (MOSI), D12 (MISO) and D13 (SCK).

Outgrowing the breadboard? Describe the project and PCBEditor designs a board that the Nano plugs into, or a standalone ATmega328P board without it.

Turn a Nano project into a board →

Sources

Other pinouts