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MSP430FR2533: Schematic Review

Muthu S
Intellectual 720 points
Part Number: MSP430FR2533
Other Parts Discussed in Thread: MSP430FR2522

Dear Team,

Please verify the schematic and layout design for Touch Keypad.

Also clarify below query.

Customer wants to use 16 Capsense Input, and 7 LED output. They have selected MSP430FR2533 - 32pin. But We have suggested MSP430FR2522-16pin IC. Considering that, need Matrix keypad 4X4 by configuring Mutual capacitance. Is it possible to use MSP430FR2522-16 pin for 16-Capsense keypad and 7 LED output?

Regards,

Muthu S

sch-capkey-v100.pdfBoard file and Gerber.rar

  • 0
    TI__Expert 5490 points
    Hello Muthu,

    We will take look at the schismatic and layout and provide feedback to you asap.
    Do you know what is the thickness of the overlay on top of the sensor baord?

    The MSP430FR2522 16pin package will not have enough pins to support 16 buttons and 7 LEDs. Since 16 buttons take 4x4 = 8 pin and plus 7 LEDs which take 7 pins total you need 15 pins. The number of GPIO pins on the 16 pin packages is 11 because you need consider Vcc, GND, Test, Rest pins.
    Also they are using I2C and UART communication on the device so overall they will not have enough pins for the 16 pin package.

    Thanks,
    Yiding
  • 0 in reply to Yiding Luo
    Intellectual 720 points

    Dear Yiding,

    Thanks for your reply.

    The overall thickness of the overlay is 4.5mm.

    How about MSP430FR2522IRHLR - 20 pin package for this application? It has 15 GPIO's.

    Also please note that the distance between two keypad (3mm). Let me your feedback.

    Regards,

    Muthu S

  • 0 in reply to Muthu S
    Intellectual 720 points
    Dear Yiding,

    Can you please update the feedback on schematic and clarify the previous mail?


    Regards,
    Muthu S
  • 0 in reply to Muthu S
    TI__Expert 5490 points
    Hello Muthu,

    Apologize for the delay here and we are still reviewing your layout and will get back to you soon.
    For your question on FR2522, they will not have enough pins either since FR2522 has 15 gpios and the cap touch takes 8, LEDs takes 7, and based on your schematic you also have the I2C and UART communication and the crystal.

    For schematic:
    1. You do not need the pull up and pull down resistor for the "TEST" pin.

    I have couple of questions regarding your layout:
    1. What is the size of the buttons?
    2. Is this a line powered application?
    3. There is no air gap between the overlay and the sensor PCB right?

    Thanks,
    Yiding
  • 0
    TI__Expert 5490 points
    Hello Muthu,

    To have better sensitivity over the 4.5mm overlay I will recommend:
    1. Increase the space between top layer GND poly pour and around the button electrode.
    2. For bottom layer, use hatched poly pour under the button electrode area.
    3. Air gap can also reduce the sensitivity so make sure there is no air gap between the overlay and the PCB.

    Please let me know if you have any more questions.

    Thanks,
    Yiding

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