[arduino code examples for DM4]-02 Read digital input ports state

Code:
/*

 KeyPressed on PIN1

 by Mischianti Renzo <http://www.mischianti.org>



 https://www.mischianti.org/2019/01/02/pcf8574-i2c-digital-i-o-expander-fast-easy-usage/

*/



#include "Arduino.h"

#include "PCF8574.h"



// Define I2C pins

#define I2C_SDA 8   // SDA pin

#define I2C_SCL 18  // SCL pin



// Set i2c address

PCF8574 pcf8574(0x24);

unsigned long timeElapsed;

void setup()

{

    Wire.begin(I2C_SDA, I2C_SCL);

    Serial.begin(115200);

    delay(1000);



//    pcf8574.pinMode(P0, OUTPUT);

 pcf8574.pinMode(P0, INPUT);

 pcf8574.pinMode(P1, INPUT);

 pcf8574.pinMode(P2, INPUT);

 pcf8574.pinMode(P3, INPUT);





    Serial.print("Init pcf8574...");

    if (pcf8574.begin()){

        Serial.println("OK");

    }else{

        Serial.println("KO");

    }

}



void loop()

{

 uint8_t val1 = pcf8574.digitalRead(P0);

 uint8_t val2 = pcf8574.digitalRead(P1);

 uint8_t val3 = pcf8574.digitalRead(P2);

 uint8_t val4 = pcf8574.digitalRead(P3);



 if (val1==LOW) Serial.println("KEY1 PRESSED");

 if (val2==LOW) Serial.println("KEY2 PRESSED");

 if (val3==LOW) Serial.println("KEY3 PRESSED");

 if (val4==LOW) Serial.println("KEY4 PRESSED");



    delay(300);

}