So your touch sensor is not working?

sensorWe have all experienced it, you buy something at Aliexpress. It arrives and you confirm receipt before you have time to test everything and then when you finally get around to that… there is a problem.
That happened to me with a TTP223B capacitive touch sensor. Whatever I tried, the output remained low. Slightly frustrated I was looking at the rather simple board and thought that there really couldn’t be much wrong with it.
ttp223-icFound a datasheet of the TTP223B ic that is on this module and started measuring. Well to make a long story short, the input pin (pin 3) seemed to have no connection with the sensorplate. When I would just touch the input pin, it switched very well. According to an application note in the datasheet capacitor C1 should be between  the input and  the ground and as it should be connected it also should be connected to the  sensorplate, which in fact it was. Turns out pin 3 was not connected to anything. A small wire that I soldered between the top of C1 and  pin 3 remedied everything and after that the sensor worked wonder well.
On checking the feedback of people who ordered this sensor, I noticed many experienced the same problem. No doubt the manufacturer (not perse the seller) must have known about this.



17 thoughts on “So your touch sensor is not working?”

  1. Do not matter if manufacturer know about this bug or not. I am sure, that seller got many of these boards and he will sell them, do not matter if it has bug or not.

    BTW you can add additional feedback on aliexpress for circa 6 months and open case 15 days after confirmation…


    1. I am sure you are right and if he didnthe does now as i told him. Tried the additional fedback but couldnt find it

  2. Dear Mr Arduino. I’d like to ask you some question about my project thats using peltier, i just have a thought that you might be able to help me. Could i get your email maybe? or any other way i can contact you, since i can’t attach any picture here to help you understand my problem. Iam a student in a polytechnic and last year, you already help me a lot with my final project by replying my comment on this website on your “Arduino Dimmer” tutorial. Thank you so much for that and please reply me :))

    1. That seems to be the same on that I had and that was fAulty. Is it perhaps close to a metal surface? Try a 100nf capacitor o er the vcc and ground of the module

  3. hiii sir Iam trying to interface the touch sensor with Arduino Uno it’s working but I don’t know it was automatically turned on and off I don’t know please anybody give some suggestions about touch sn sensors thank you.

    1. I am not exactly sure what it is you are asking. The touch sensor in yr link has a vcc, a ground and a signal pin, clearly indicated on the pcb. Vcc and ground go to the corresponding pins of the arduino and the signal pin to a digital pin of the uno

  4. I want to interface the heart rate ecg module to Arduino nano I tried to interface the connection but the plot in serial monitoring was displays only one minute otherwise it was not working , please give solution to draw the plot in continuous plotting for ecg module thank you.

    1. That is a totally unrelated question. The plotting usually is not done by the arduino in the serial monitor but by a program getting data from the serial afaik

    1. The fix I describe IS for a specific TTP223 module. It works because it fixes a design flaw in the PCB.
      Wheter it works for ANY TTP223 module that is not working, I do not know, but if you have one similar to the one in my picture, chances are it is the same module, but if you check the PCB it is quite easy to see if the specific pin is attached to the touch surface or not

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