The PCF8583 is a small 8-pin clock and calendar chip from NXP Semiconductors with full binary coded decimal (BCD) clock/calendar plus 2048 RAM (256 by 8 RAM memory) that is used in microcontroller based systems to provide real time date and time information. Data and Addresses are transferred serially through a bidirectional I2C bus. The PCF8583 RTC provides year, month, date, hour, minute and second information. The built-in word address register is incremented automatically after each written or read data byte. Address pin A0 is used for programming the hardware address, allowing the connection of two devices to the bus without additional hardware