Nixie clock: 3 – RTC and expander

luca 16/03/2012 13

In this third blog post, I’m going to show you the logical view of my Nixie clock and two of its main elements: the real time clock, to keep track of the current time, and the expander, to add more I/O lines.

Logical view

Here are my clock’s main elements:

  • A power supply with 5V (for Arduino and modules) and 170V (for Nixie tubes) outputs;
  • an Arduino Mini;
  • a touch-sensor module (will be described in a following post);
  • an RTC module, connected via I2C bus;
  • an IC to add some I/O ports to Arduino, connected via I2C bus too;
  • four 74141 Nixie tube drivers;
  • four ZM1177 Nixie tubes.

In the next page, some details about two of those elements…

Pages: 1 2 3 4


  1. pitchoilcan 06/04/2012 at 06:19 - Reply

    I get :error:
    PCF8575_Led_rolling_Demo.cpp: In function ‘void loop()’:
    PCF8575_Led_rolling_Demo.cpp:24:8: error: ‘class TwoWire’ has no member named ‘write’
    PCF8575_Led_rolling_Demo.cpp:25:8: error: ‘class TwoWire’ has no member named ‘write’
    I able to compile by change it for
    but still now a blink from any of the LED’s. Are you using any resistor? I”ve tryed it using just the pcf8575 anf an arduino board, no RTC module. Is that doable and if so what I’m I doing wrong?

    • luca 10/04/2012 at 08:07 - Reply


      You’re probably using an older (< 1.0) version of Arduino IDE… anyway you don’t need a RTC module for this example, could you post your connections so I can check?

  2. pitchoilcan 06/04/2012 at 07:15 - Reply
  3. Fernando Garcia 25/12/2012 at 18:27 - Reply


    I’m trying to build a circuit with a RTC and a PCF8575 .

    It happens that the RTC does not tell the correct time.
    There must be some conflict.

    The code I’m using to test is this:

  4. Fernando Garcia 25/12/2012 at 18:43 - Reply

    The code does not appear correctly.

    Here’s a link to it.

    Best regards.

    • luca 11/01/2013 at 08:32 - Reply

      Hi Fernando,

      are you using an Arduino Mega?

  5. Dmitry 19/03/2015 at 09:15 - Reply

    Hello Luca.
    Thanx for your manual!

    Could you advise IO extender on 24 pins (for 6 tubes)?

    I’ve found the Tca6424rgjr but probably there is something better.

    • luca 19/03/2015 at 11:15 - Reply

      Hi Dmitry… it depends on you: on the I2C bus you can connect more than one expander, therefore you can use 3 8-pins expanders or the one you found that works fine!

  6. DRS 30/11/2015 at 11:50 - Reply

    Hi, where i can read more about power supply ?

  7. Mauro 06/09/2016 at 10:07 - Reply

    Ciao Luca,
    non riesco a compilare NESSUN esempio che utilizza il pcf8575!
    Ho scaricato le librerie da github le istallo ma gli esempi Blinkled non si compilano . dice che manca il file PCG8575.h.
    Dove sbaglio ?

  8. Mauro 19/10/2016 at 14:57 - Reply

    Devo usare tre 8575 in I2C e collegare ai pin digitali 2 e 3 di Arduino Nano il modulo Bluetooth HC-06 .
    Le librerie 8575.h e SoftwareSerial.h sembra che non possano convivere assieme.
    Con qualsiasi IDE con cui cerco di compilare mi da sempre:

    SoftwareSerial\SoftwareSerial.cpp.o: In function `__vector_3′:
    \\Srv01\dati\Comune\Arduino\IDE_ARDUINO\arduino-1.5.8\hardware\arduino\avr\libraries\SoftwareSerial/SoftwareSerial.cpp:306: multiple definition of `__vector_3′
    PCF8575\PCF8575.cpp.o:\\Srv01\dati\Comune\Arduino\IDE_ARDUINO\arduino-1.5.8\libraries\PCF8575/PCint.h:104: first defined here
    SoftwareSerial\SoftwareSerial.cpp.o: In function `__vector_4′:
    \\Srv01\dati\Comune\Arduino\IDE_ARDUINO\arduino-1.5.8\hardware\arduino\avr\libraries\SoftwareSerial/SoftwareSerial.cpp:313: multiple definition of `__vector_4′
    PCF8575\PCF8575.cpp.o:\\Srv01\dati\Comune\Arduino\IDE_ARDUINO\arduino-1.5.8\libraries\PCF8575/PCint.h:107: first defined here
    SoftwareSerial\SoftwareSerial.cpp.o: In function `__vector_5′:
    \\Srv01\dati\Comune\Arduino\IDE_ARDUINO\arduino-1.5.8\hardware\arduino\avr\libraries\SoftwareSerial/SoftwareSerial.cpp:320: multiple definition of `__vector_5′
    PCF8575\PCF8575.cpp.o:\\Srv01\dati\Comune\Arduino\IDE_ARDUINO\arduino-1.5.8\libraries\PCF8575/PCint.h:110: first defined here
    collect2: error: ld returned 1 exit status
    Errore durante la compilazione

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