This is a relay module for controlling external loads from a microcontroller using digital input pins. It is powered from VCC and GND, and the relay channels are driven by the IN pins for isolated on/off switching of higher-power circuits.
| Pin | Signal | Description |
|---|---|---|
GND |
ground | Logic ground reference for the relay module control inputs |
IN1 |
digital | Active-low control input for relay 1 — drive low to energize |
IN2 |
digital | Active-low control input for relay 2 — drive low to energize |
IN3 |
digital | Active-low control input for relay 3 — drive low to energize |
VCC |
power | 5V logic/module supply input for relay control circuitry |
GND.1 |
ground | Additional ground connection for the relay module logic side |
| From | To | Wire |
|---|---|---|
board:GND |
x1:GND |
black |
board:5V |
x1:VCC |
red |
board:D4 |
x1:IN1 |
green |
board:D5 |
x1:IN2 |
blue |
board:D6 |
x1:IN3 |
yellow |
This example was written and compile-checked for the arduino-uno. Codey Online adapts it to any other supported board for you.
const int RELAY1_PIN = 4;
const int RELAY2_PIN = 5;
const int RELAY3_PIN = 6;
void setup() {
Serial.begin(9600);
pinMode(RELAY1_PIN, OUTPUT);
pinMode(RELAY2_PIN, OUTPUT);
pinMode(RELAY3_PIN, OUTPUT);
// Most 5V relay modules are active-low:
// HIGH = relay off, LOW = relay on.
digitalWrite(RELAY1_PIN, HIGH);
digitalWrite(RELAY2_PIN, HIGH);
digitalWrite(RELAY3_PIN, HIGH);
Serial.println("3-Channel Relay Module demo starting...");
}
void loop() {
Serial.println("Relay 1 ON");
digitalWrite(RELAY1_PIN, LOW);
delay(1000);
digitalWrite(RELAY1_PIN, HIGH);
Serial.println("Relay 2 ON");
digitalWrite(RELAY2_PIN, LOW);
delay(1000);
digitalWrite(RELAY2_PIN, HIGH);
Serial.println("Relay 3 ON");
digitalWrite(RELAY3_PIN, LOW);
delay(1000);
digitalWrite(RELAY3_PIN, HIGH);
Serial.println("All relays OFF");
delay(1000);
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