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Real Time Clock PCF8583 Using AVR microcontroller


The PCF8583 is a clock/calendar circuit based on a 2048-bit static CMOS RAM organized as 256 words by 8 bits. Addresses and data are transferred serially via the two-line bidirectional I2C-bus. 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.The built-in 32.768 kHz oscillator circuit and the first 8 bytes of the RAM are used for the clock/calendar and counter functions. The next 8 bytes may be programmed as alarm registers or used as free RAM space. The remaining 240 bytes are free RAM locations


  • I2C-bus interface operating supply voltage: 2.5 V to 6 V
  • Clock operating supply voltage (0 to +70 °C): 1.0 V to 6.0 V
  • 240 ´ 8-bit low-voltage RAM· Data retention voltage: 1.0 V to 6 V
  • Operating current (at fSCL = 0 Hz): max. 50 mA
  • Clock function with four year calendar
  • Universal timer with alarm and overflow indication
  • 24 or 12 hour format· 32.768 kHz or 50 Hz time base
  • Serial input/output bus (I2C)
  • Automatic word address incrementing
  • Programmable alarm, timer and interrupt function
  • Slave address:– READ: A1 or A3– WRITE: A0 or A2.





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