Relay module with Teensy 4.1

Wiring for the Relay module 1 channel (5 V) on the Teensy 4.1 (MIMXRT1062DVJ6B, 3.3 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	Teensy 4.1 pin	Notes
IN	Input to the part	2 (GPIO_EMC_04)	Many modules switch on with IN LOW. Some do not react to 3.3 V: check with a test
GND	Ground	G
VCC	Power	3V	Needs 5 V for the coil: use 3V
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: 3.3 V from the 3V pin.
Motors, servos, relays and LED strips can draw more current than the Teensy 4.1’s pins or USB can give. Power them separately and connect the grounds together.

Test code (Arduino)

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

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

Arduino board: teensy:avr:teensy41. Press the white program button once if the upload waits for the board.

Questions

Which Teensy 4.1 pins do I use for the Relay module?

IN → 2 (GPIO_EMC_04), GND → G, VCC → 3V.

Does the Relay module work with the Teensy 4.1 at 3.3 V?

Yes: the Relay module runs at 5 V and the Teensy 4.1 uses 3.3 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 Teensy 4.1 pinout · Relay module 1 channel (5 V): all pins and data

The Relay module on other boards

ESP32 DevKit Arduino Mega 2560 R3 Arduino Nano 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

Other parts on the Teensy 4.1

BME280 BMP280 DHT22 DHT11 HC-SR04 SSD1306 OLED MPU6050 DS18B20 WS2812B LED strip SG90 servo HC-SR501 PIR LCD 1602 I2C INA219 VL53L0X BH1750 MAX30102 RC522 RFID NEO-6M GPS Capacitive soil moisture sensor ADS1115 TM1637 28BYJ-48 stepper L298N Potentiometer Push button LED Joystick module SD card module AHT20