Code:
/*
* Made by KinCony IoT: https://www.kincony.com
*
* This program reads 4 input states from a PCF8574 I/O expander and
* controls a corresponding 4-channel relay module. When an input pin
* is LOW, the corresponding relay is turned ON (LOW means ON for the relay).
*
* Pin Definitions:
* - SDA: GPIO 8
* - SCL: GPIO 18
* - PCF8575 I2C Address: 0x24
*/
#include <Wire.h>
#include <PCF8574.h>
// I2C pins
#define SDA 8
#define SCL 18
// PCF8575 I2C address
#define INPUT_I2C_ADDRESS 0x24
// Create PCF8575 object
PCF8574 pcf8574_IN(INPUT_I2C_ADDRESS);
void setup() {
// Initialize I2C communication
Wire.begin(SDA, SCL);
// Initialize serial communication
Serial.begin(115200);
pcf8574_IN.pinMode(P0, INPUT);
pcf8574_IN.pinMode(P1, INPUT);
pcf8574_IN.pinMode(P2, INPUT);
pcf8574_IN.pinMode(P3, INPUT);
pcf8574_IN.pinMode(P4, OUTPUT);
pcf8574_IN.pinMode(P5, OUTPUT);
pcf8574_IN.pinMode(P6, OUTPUT);
pcf8574_IN.pinMode(P7, OUTPUT);
// Initialize PCF8575
pcf8574_IN.begin();
// Turn off all relays first (assuming LOW activates the relay)
for (int i = 4; i < 8; i++) {
pcf8574_IN.digitalWrite(i, HIGH); // Set to HIGH to turn off the relay
}
delay(50);
}
void loop() {
if (pcf8574_IN.digitalRead(0)) pcf8574_IN.digitalWrite(4, HIGH); else pcf8574_IN.digitalWrite(4, LOW);
delay(50);
if (pcf8574_IN.digitalRead(1)) pcf8574_IN.digitalWrite(5, HIGH); else pcf8574_IN.digitalWrite(5, LOW);
delay(50);
if (pcf8574_IN.digitalRead(2)) pcf8574_IN.digitalWrite(6, HIGH); else pcf8574_IN.digitalWrite(6, LOW);
delay(50);
if (pcf8574_IN.digitalRead(3)) pcf8574_IN.digitalWrite(7, HIGH); else pcf8574_IN.digitalWrite(7, LOW);
delay(50);
}
