PCF8574 IO Expansion i2c digital input board -DI8 arduino demo code

Code:
#include "Arduino.h"

#include "PCF8574.h"

// Set i2c address

PCF8574 pcf8574(0x27,4,5); //4 is SDA 5 is SCL need replace by your board's pin define 

/*

A0  A1  A2

0    0    0    =0x20

0    0    1    =0x21

0    1    0    =0x22

0    1    1    =0x23

1    0    0    =0x24

1    0    1    =0x25

1    1    0    =0x26

1    1    1    =0x27

*/

unsigned long timeElapsed;

void setup()

{

    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);

 pcf8574.pinMode(P4, INPUT);

 pcf8574.pinMode(P5, INPUT);

 pcf8574.pinMode(P6, INPUT);

 pcf8574.pinMode(P7, 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);

 uint8_t val5 = pcf8574.digitalRead(P4);

 uint8_t val6 = pcf8574.digitalRead(P5);

 uint8_t val7 = pcf8574.digitalRead(P6);

 uint8_t val8 = pcf8574.digitalRead(P7);

 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");

 if (val5==LOW) Serial.println("KEY5 PRESSED");

 if (val6==LOW) Serial.println("KEY6 PRESSED");

 if (val7==LOW) Serial.println("KEY7 PRESSED");

 if (val8==LOW) Serial.println("KEY8 PRESSED");

    delay(300);

}