Nixie clock: 4 – the touch sensor

by luca

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:

[youtube id=”nAfE9ERd7BY” width=”600″ height=”350″]

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Tellus Sunday March 3rd, 2013 - 08:40 PM

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

luca Sunday March 3rd, 2013 - 09:51 PM

ciao, ti ho mandato una mail

Chris Thursday August 15th, 2013 - 01:43 PM

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

safak Monday October 28th, 2013 - 02:15 PM

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

luca Monday October 28th, 2013 - 11:01 PM Reply
shafak Friday November 15th, 2013 - 11:02 PM

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 Saturday November 16th, 2013 - 10:49 AM

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.

shafak Friday November 22nd, 2013 - 02:14 AM

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?

shafak Friday November 22nd, 2013 - 05:22 AM

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 Wednesday November 27th, 2013 - 02:25 PM


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

ibrahim Sunday November 24th, 2013 - 12:04 AM

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 😀

luca Wednesday November 27th, 2013 - 02:24 PM

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).

shafak Wednesday November 27th, 2013 - 08:39 PM

thanks for your dear sharings…

Andrea Sunday January 31st, 2016 - 02:55 PM

L’orologio una volta finito quanti watt consuma?

luca Monday February 1st, 2016 - 08:01 PM

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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