Documentation

// 4-Channel 12V Relay Module - Arduino Example
// Active LOW: digitalWrite(pin, LOW) energizes the relay.
// IN pins: 7, 8, 9, 10

void setup() {
  Serial.begin(9600);
  pinMode(7, OUTPUT);
  digitalWrite(7, HIGH);  // start with relay OFF
  pinMode(8, OUTPUT);
  digitalWrite(8, HIGH);  // start with relay OFF
  pinMode(9, OUTPUT);
  digitalWrite(9, HIGH);  // start with relay OFF
  pinMode(10, OUTPUT);
  digitalWrite(10, HIGH);  // start with relay OFF
}

void loop() {
  // Cycle through each relay one by one
  digitalWrite(7, LOW);   // Relay 1 ON
  delay(500);
  digitalWrite(7, HIGH);  // Relay 1 OFF
  delay(500);
  digitalWrite(8, LOW);   // Relay 2 ON
  delay(500);
  digitalWrite(8, HIGH);  // Relay 2 OFF
  delay(500);
  digitalWrite(9, LOW);   // Relay 3 ON
  delay(500);
  digitalWrite(9, HIGH);  // Relay 3 OFF
  delay(500);
  digitalWrite(10, LOW);   // Relay 4 ON
  delay(500);
  digitalWrite(10, HIGH);  // Relay 4 OFF
  delay(500);
}

// 4-Channel 12V Relay Module - ESP32 Arduino Example
// IN pins: GPIO 5, 18, 19, 21
// Active LOW logic.

void setup() {
  Serial.begin(115200);
  pinMode(5, OUTPUT);
  digitalWrite(5, HIGH);  // start OFF
  pinMode(18, OUTPUT);
  digitalWrite(18, HIGH);  // start OFF
  pinMode(19, OUTPUT);
  digitalWrite(19, HIGH);  // start OFF
  pinMode(21, OUTPUT);
  digitalWrite(21, HIGH);  // start OFF
}

void loop() {
  digitalWrite(5, LOW);   // Relay 1 ON
  delay(500);
  digitalWrite(5, HIGH);  // Relay 1 OFF
  delay(500);
  digitalWrite(18, LOW);   // Relay 2 ON
  delay(500);
  digitalWrite(18, HIGH);  // Relay 2 OFF
  delay(500);
  digitalWrite(19, LOW);   // Relay 3 ON
  delay(500);
  digitalWrite(19, HIGH);  // Relay 3 OFF
  delay(500);
  digitalWrite(21, LOW);   // Relay 4 ON
  delay(500);
  digitalWrite(21, HIGH);  // Relay 4 OFF
  delay(500);
}

#!/usr/bin/env python3
# 4-Channel 12V Relay Module - Raspberry Pi Example
# IN pins: GPIO 17, 27, 22, 23 (BCM)
# Active LOW logic.

import RPi.GPIO as GPIO
import time

PINS = [17, 27, 22, 23]

GPIO.setmode(GPIO.BCM)
for p in PINS:
    GPIO.setup(p, GPIO.OUT, initial=GPIO.HIGH)  # start OFF

try:
    while True:
        GPIO.output(17, GPIO.LOW)   # Relay 1 ON
        time.sleep(0.5)
        GPIO.output(17, GPIO.HIGH)  # Relay 1 OFF
        time.sleep(0.5)
        GPIO.output(27, GPIO.LOW)   # Relay 2 ON
        time.sleep(0.5)
        GPIO.output(27, GPIO.HIGH)  # Relay 2 OFF
        time.sleep(0.5)
        GPIO.output(22, GPIO.LOW)   # Relay 3 ON
        time.sleep(0.5)
        GPIO.output(22, GPIO.HIGH)  # Relay 3 OFF
        time.sleep(0.5)
        GPIO.output(23, GPIO.LOW)   # Relay 4 ON
        time.sleep(0.5)
        GPIO.output(23, GPIO.HIGH)  # Relay 4 OFF
        time.sleep(0.5)
except KeyboardInterrupt:
    print("Stopped by user")
finally:
    for p in PINS:
        GPIO.output(p, GPIO.HIGH)  # ensure OFF
    GPIO.cleanup()

# 4-Channel 12V Relay Module - Pico MicroPython Example
# IN pins: GP2, GP3, GP4, GP5
# Active LOW logic.

from machine import Pin
from time import sleep

relay1 = Pin(2, Pin.OUT, value=1)  # start OFF (HIGH)
relay2 = Pin(3, Pin.OUT, value=1)  # start OFF (HIGH)
relay3 = Pin(4, Pin.OUT, value=1)  # start OFF (HIGH)
relay4 = Pin(5, Pin.OUT, value=1)  # start OFF (HIGH)

try:
    while True:
        relay1.value(0)  # Relay 1 ON
        sleep(0.5)
        relay1.value(1)  # Relay 1 OFF
        sleep(0.5)
        relay2.value(0)  # Relay 2 ON
        sleep(0.5)
        relay2.value(1)  # Relay 2 OFF
        sleep(0.5)
        relay3.value(0)  # Relay 3 ON
        sleep(0.5)
        relay3.value(1)  # Relay 3 OFF
        sleep(0.5)
        relay4.value(0)  # Relay 4 ON
        sleep(0.5)
        relay4.value(1)  # Relay 4 OFF
        sleep(0.5)
except KeyboardInterrupt:
    print("Stopped by user")