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MSP430FR2000: About capacitive touch using a large iron disk as an electrode

O.H
Genius 5710 points
Part Number: MSP430FR2000
Other Parts Discussed in Thread: MSP430FR2311, MSP430FR2111, MSP430WARE

Hi experts,

Please let me check about capacitive touch. The customer is currently considering a capacitive touch using MSP430 with an iron disk of 12~30cm in diameter as an electrode.

We are considering the following three patterns.

  1. Use the comparator of MSP430FR2000 and attaching an external oscillator that changes with capacitance.
  2. Use the Capacitive Touch I/O of MSP430FR2000.
  3. Use MSP430FR2521's CapTIvate to do this.

The customer originally used the first method with another company's microcontroller. Considering the cost and man-hours, they think No.1 or No.2 would be ideal.

Here is a question.

Q1. Do you have a sample code to evaluate the CapacitiveTiouch I/O?
I looked for a link in the Capacitive Touch Software Library (Rev. D) and TI Resource Explorer, but couldn't find it. We would appreciate it if you could give us the latest information.

Q2. Is it difficult to detect touch when the electrode is an iron disk of 12~30cm in diameter?
For the CapTIvate, we did a simple experiment using a copper foil sheet with a diameter of 20cm, and it seemed to work well. For methods No.1, 2, and 3, any advice on using a larger electrode would be appreciated.

Best regards,
O.H

  • 0
    TI__Mastermind 49692 points

    Hello,

    Our legacy PinOsc Capacitive Touch approach is obsolete. While it's possible to implement on certain MSP430 MCUs, unfortunately it is no longer supported by TI. Instead, we recommend customers use our CapTIvate MCUs for capacitive touch applications. Please feel free to search the forum for posts that may help answer this question.

  • 0 in reply to James Evans
    Genius 5710 points

    Hello,

    Thank you for your reply. I understood the situation.

    I found a sample code for evaluating Capacitive Touch I/O(PinOsc) on MSP430FR2311 in an old MSP430Ware(3_30_00_18). I tried to run it on MSP430FR2111, and it seems to work. By the way, I couldn't build it on FR2000 because of insufficient FRAM capacity.

    Q3:If possible, can you tell us about the points to be aware of and concerns in proceeding with Capacitive Touch I/O(PinOsc)?

    I understand that it is best to proceed with CapTIvate in this situation, but it would be helpful if I could understand the points to be aware of with Capacitive Touch I/O.

    Best regards,
    O.H

  • +1 in reply to O.H
    TI__Mastermind 49692 points

    Hello,

    I would recommend searching online to find any PinOsc-related documents. Because it is obsolete, most if not all of those documents have been removed from TI.com.

  • 0 in reply to James Evans
    Genius 5710 points

    Hello,

    Thanks for the advice. I will look for it and refer to it whenever possible.

    Best regards,
    O.H

  • 0 in reply to O.H
    TI__Mastermind 49692 points

    Sounds good. I'm sorry that I can't assist more.

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