Nixie clock: 4 – the touch sensor

luca 27/02/2013 15

My Nixie clock won’t have any visible buttons, so I chose to use a touch sensor, that signals to Arduino when the user touches the clock.

I brought from SureElectronics the Capacitive Proximity and Touch Button Control module, based on the IQS127D IC by Azoteq. You can download its datasheet and an important application note about how it detects a “touch” and how to design the sensing pads to optimize the detection process.

This IC can sense one touch pad and offers two digital outputs: proximity (red) and touch (yellow). SureElectronics included in the module two leds that show the output’s state:

The ouputs are normally (= no touch detected) at logic level high:

  • if a finger comes near the sensing pad, POUT output is grounded;
  • if a finger touches the pad, both POUT and TOUT are grounded.

It’s very easy to connect this sensor to Arduino: you need only two digital PINs to read (set them as INPUT) the status of the two outputs.

Using the ANT PIN you can connect to the sensor an external sensing “antenna”: it could be just a wire, a pad on a PCB…

The IC has an automatic antenna tuning algorithm (ATI) that detects external antenna’s peculiarities and automatically adapts to it.

The Automatic Antenna Tuning feature runs at power on: if you are testing different types of antennas remember to power cycle the IC at every change

I tested different materials (plastic, glass…) in front of my antenna (a wire) and the sensor was always able to detect my finger; here’s a short video about my tests:


  1. Tellus 03/03/2013 at 20:40 - Reply

    Scusa luca…. ho letto numerosi tuoi articoli e vorrei chiederti una cosa abbastanza complessa. Dove posso contattarti?
    p.s non facebook.

    • luca 03/03/2013 at 21:51 - Reply

      ciao, ti ho mandato una mail

  2. Chris 15/08/2013 at 13:43 - Reply

    Love the nixie clock so far. Please post updates and finish so we can admire your work!

  3. safak 28/10/2013 at 14:15 - Reply

    Could you write the name of touch/proximity module in SureElectronic or the link the web-page?
    Thank you…

  4. shafak 15/11/2013 at 23:02 - Reply

    hi. I want to use the IC of ISQ127 which is used in the module. How can programme this IC without module? and How can you programme this module? If you know, could you give me briefly information.

    • luca 16/11/2013 at 10:49 - Reply

      Hi shafak, could you please explain what you need? The IC can’t be “programmed”, it’s a sensor that gives you a “feedback” (= electric signal) about the proximity of a finger… all the logic is done by an external (in my case Arduino) microcontroller.

  5. shafak 22/11/2013 at 02:14 - Reply

    Firstly, thank you for your interest and sorry for my jump to answer. I mean that IQS127 need one time programme if my understood is right. Also there are Azoteq USBpro.exe on datasheet of IQS127. Also there are some progrogramming stage as an example. May be, it can be different think but I can not understand. As my understood, we need to decide active low or active high for using IQS127. So, what can I do?

  6. shafak 22/11/2013 at 05:22 - Reply

    Firstly, thanks for your interest and sorry for jump to answer. I think I solved my problem but I have a trouble by programming arduino? Which code should I use? Could you help me? How can I programme to arduino? Thanks…

    • luca 27/11/2013 at 14:25 - Reply


      on the Arduino side you need only to use the digitalRead() function to read the outputs of the sensor.

  7. ibrahim 24/11/2013 at 00:04 - Reply

    it s great…firstly thanks for your sharing. I want to learn how did you write ardunio code for that. Shortly, I need the code and your help :D

    • luca 27/11/2013 at 14:24 - Reply

      Hi Ibrahim

      in my example I didn’t write any line of code for arduino ;) the sensor has digital outputs so read those outputs with Arduino is very simple (digitalRead).

  8. shafak 27/11/2013 at 20:39 - Reply

    thanks for your dear sharings…

  9. Andrea 31/01/2016 at 14:55 - Reply

    L’orologio una volta finito quanti watt consuma?

    • luca 01/02/2016 at 20:01 - Reply

      Ciao Andrea, le nixie consumano abbastanza poco… 2.5mA l’una quindi sei nell’ordine dei 10mA totali. Il consumo maggiore sta nei moduli (Arduino…) e negli eventuali LED che aggiungi per illumionarle. Stima 5-10W per tutto alimentando a 12V.

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