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[Tip] Nice realtime clock with the PCF8563

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Hi everybody,


As a part of my long term project building wireless sensor nodes, I have been looking for a nice RTC chip. First I was drawn to the DS1307, but this part is 5V and only a clock without alarm functions. Googling to the internet I've found the PCF8563. This part is a "drop in" replacement for the DS1307, but offers a lower supply voltage (3.3V) and includes alarm functions. The chips can be sourced quite cheap from the internet and work like a charm with both 6pf and 12pf 32768kHz crystals.


A nice tutorial how to connect these things can be found using the following link: http://startingelectronics.com/beginners/start-electronics-now/tut16-arduino-clock/


It is written for the Arduino but can be adapted easily to the launchpad. Just change the LiquidCrystal pins to free pins on the Arduino and voila there you have a nice RTC that can be used for sprinkler projects or other projects. The alarm can be set on different days of the week (not a specific date), but with some program logic a calendared version should be possible.


I am thinking of writing a library out of the tutorial. Anyone interested?


Kind regards,



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The PCF2129A is a SOIC20 package. I've soldered it on a DIP14 support and I'm using it in I2C mode.
post-12238-0-45271500-1377675921_thumb.jpg post-12238-0-68225000-1377676394_thumb.png
For I2C
  • SCL(1) = I2C clock
  • SDA(4) = I2C data
  • IFS(5) connected to BBS(18) = output voltage to select I2C
  • SDI(2) connected to VSS(8) = ground
  • VDD(20) = +3.3V
  • VBAT(19) = optional battery 
  • VSS(8) = ground

For I2C, don't forget to use pull-ups resistors for SDA and SCL.



For SPI, not tested
  • SCL(1) = SPI clock
  • SDI(2) = SPI MOSI
  • SDO(3) = SPI MISO
  • CE(4) = SPI chip enable, active low
  • IFS(5) connected to VSS(8) = ground to select SPI
  • VDD(20) = +3.3V
  • VBAT(19) = optional battery 
  • VSS(8) = ground
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