Relay module with Arduino Nano

Wiring for the Relay module 1 channel (5 V) on the Arduino Nano (ATmega328P, 5 V logic), chosen with the same pin rules BoardPilot uses: default buses first, and no pins that are used for flash, USB, the debugger or booting.

Wiring

Relay module pin	Role	Arduino Nano pin	Notes
IN	Input to the part	D2 (PD2)	Many modules switch on with IN LOW. Some do not react to 3.3 V: check with a test
GND	Ground	GND
VCC	Power	5V	Needs 5 V for the coil: use 5V
COM	Not wired to the board	not connected	Relay common contact. Mains voltage is dangerous
NO	Not wired to the board	not connected	Normally open contact
NC	Not wired to the board	not connected	Normally closed contact

Check before you power it on

Supply: 5 V from the 5V pin.
Motors, servos, relays and LED strips can draw more current than the Arduino Nano’s pins or USB can give. Power them separately and connect the grounds together.

Test code (Arduino)

void setup() {
  pinMode(2, OUTPUT);  // IN on D2
}

void loop() {
  digitalWrite(2, HIGH);
  delay(500);
  digitalWrite(2, LOW);
  delay(500);
}

Arduino board: arduino:avr:nano. Clones with the old bootloader upload at 57600 baud: choose “ATmega328P (Old Bootloader)” if uploads fail.

Questions

Which Arduino Nano pins do I use for the Relay module?

IN → D2 (PD2), GND → GND, VCC → 5V.

Does the Relay module work with the Arduino Nano at 5 V?

Yes: the Relay module runs at 5 V and the Arduino Nano uses 5 V signals, so no level shifting is needed.

BoardPilot checks this wiring in 3D as you build it, and finds crossed or missing wires on the real board.

Download BoardPilot

Full Arduino Nano pinout · Relay module 1 channel (5 V): all pins and data

The Relay module on other boards

ESP32 DevKit Arduino Mega 2560 R3 Arduino Uno R3 WeAct Black Pill STM32F411CE ESP32-C3-DevKitM-1 ESP32-S3-DevKitC-1 Nordic nRF52840 DK NUCLEO-F401RE Raspberry Pi Pico 2 Raspberry Pi Pico W Raspberry Pi Pico Teensy 4.1

Other parts on the Arduino Nano

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