View source for Programming PCF85263AT with Arduino IDE

Reference page 9 for the PCF85263AT-RTC data registers in the data sheet: https://www.nxp.com/docs/en/data-sheet/PCF85263A.pdf <br>
Connect '''Pin 5 (SDA) & Pin 4 (SCL)''' on the PCF8526AT board to '''Pin A5 (SDA) & Pin A4 (SCL)''' on the Arduino Uno<br> 
Copy and Paste the PCF85263AT RTC program into the Arduino IDE.<br>
Update the values in the void setup() second, minute, hour, dayOfWeek, dayOfMonth, month, year to the current values.<br>
Test to make sure everything was entered correctly by clicking on the Check-mark. Correct any errors.<br>
Upload the program to the Arduino Uno.<br>
'''PCF85263AT-RTC.INO'''
 // PCF85263AT RTC write/read demonstration
 #include "Wire.h"              //Enable I2C library
 #define PCF85263address 0x51   //define I2C address 
 byte second, minute, hour, dayOfWeek, dayOfMonth, month, year;
 String days[] = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday" };
 byte bcdToDec(byte value)
 {
  return ((value / 16) * 10 + value % 16);
 }
 byte decToBcd(byte value)
 {
  return (value / 10 * 16 + value % 10);
 }
 void setPCF85263()            // this function sets the time and date to the PCF85263
  
  {
    Wire.beginTransmission(PCF85263address);
    Wire.write(0x01);
    Wire.write(decToBcd(second));  
    Wire.write(decToBcd(minute));
    Wire.write(decToBcd(hour));     
    Wire.write(decToBcd(dayOfMonth));
    Wire.write(decToBcd(dayOfWeek));  
    Wire.write(decToBcd(month));
    Wire.write(decToBcd(year));
    Wire.endTransmission();
  }
 void readPCF85263()          // this gets the time and date from the PCF85263
  {
    Wire.beginTransmission(PCF85263address);
    Wire.write(0x01);
    Wire.endTransmission();
    Wire.requestFrom(PCF85263address, 7);
    second     = bcdToDec(Wire.read() & B01111111); // remove VL error bit
    minute     = bcdToDec(Wire.read() & B01111111); // remove unwanted bits from MSB
    hour       = bcdToDec(Wire.read() & B00111111); 
    dayOfMonth = bcdToDec(Wire.read() & B00111111);
    dayOfWeek  = bcdToDec(Wire.read() & B00000111);  
    month      = bcdToDec(Wire.read() & B00011111); // remove century bit, 1999 is over
    year       = bcdToDec(Wire.read());
  }
 void setup()
  {
    Wire.begin();
    Serial.begin(9600);
  // change the following to set your initial time
    second = 0;
    minute = 9;
    hour = 21;
    dayOfWeek = 0;
    dayOfMonth = 6;
    month = 1;
    year = 19;
  // comment out the next line and upload again to set and keep the time from resetting every reset
  setPCF85263();
  }
 void loop()
  {
    readPCF85263();
    Serial.print(days[dayOfWeek]); 
    Serial.print(" ");  
    Serial.print(month, DEC);
    Serial.print("/");
    Serial.print(dayOfMonth, DEC);
    Serial.print("/20");
    Serial.print(year, DEC);
    Serial.print(" - ");
    Serial.print(hour, DEC);
    Serial.print(":");
    if (minute < 10)
  {
    Serial.print("0");
  }
    Serial.print(minute, DEC);
    Serial.print(":");  
    if (second < 10)
  {
    Serial.print("0");
  }  
    Serial.println(second, DEC);  
    delay(1000);
 }


Open Console port and watch output.<br>