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MSP430FR2633: about slider capacitive touch through metal

Jerry Kuo
Expert 3845 points
Part Number: MSP430FR2633

Tool/software:

Hi team,

My customer is evaluating MSP430 on capacitive touch through metal . They need slider application. They refer to SLAA811A application note, chap 5.3. However, the document only describes "the slider application is similar to the metal wheel". Customer ask for below two information. Please help clarify. Thank you.

1.How to identify different touch position on one metal plate ?

2. Is there any real application use-case (like successful story) to be shared ?

  • 0
    TI__Mastermind 28735 points

    Hey Jerry,

    In the case of metal touch, the sensors are measuring the deflection/bend of the metal due to pressure from being touched. The way this works in a slider, is the sensors are configured in a way in which there is overlap between them so the sensors that pick up the biggest deflection and the difference between them allows you to locate the position of the touch. 

    As for success stories, I'm not sure.  We probably should ask Dennis Lehman, an engineer on my team as I know he's supported some metal touch customers in the past.  He'll be back in the office by the end of this week. 

    I will say that in my experience, a lot of customers like the metal touch demo but once they actually try and figure out their own manufacturing process, it becomes rather difficult.  As mentioned in the app note, their setup needs to be rigid enough but the metal bendy enough for it to work. Our demos accomplished that by milling out the back side of the metal in the locations of the buttons.  It also needs to be mechanically assembling by gluing the PCB, spacer, and metal cover together and aligned.  If all that works for the application/use case then it is definitely possible. 

    Thanks,

    JD     

  • 0 in reply to JD Crutchfield
    TI__Expert 3845 points

    Hi JD,

    Thanks for your information. I will forward to customer. 

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