Digital input 11.2v

[drandle1]

I am new here... I have uploaded the digital input code to the KC868-a8s-v2 from the knowledge base. SEE BELOW. When I test the voltage on the input with nothing connected, there is 11.2v read from all of the inputs. 

Why is this happening? 

How do I use the digital inputs? 

#include "Arduino.h"
#include "PCF8574.h"

// Set i2c address
PCF8574 pcf8574(0x22,4,5);// 0x22 is address, IO4 is SDA  IO5 is SCL
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);
}

[admin]

you can short digital with GND, when input 0V means "key pressed".
now you input 11.2v = NOT trigger.