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AM3354: Touchscreen controller with high resolution

shigehiro tsuda
Mastermind 9490 points

Part Number: AM3354

Hi,

I have a couple of questions about the AM3354 Touchscreen Controller.

1.
Is the Touchscreen Controller of AM 3354 correct with understanding that it is not dependent on resolution?

2.
Do you have successfully with touch panel operation with WXGA or higher using Touchscreen Controller with AM3354?
If there is not it, how much resolution do you have the infromation with the resolution?

3.
Are you concerned about concerns when operating at WXGA resolution?
Especially I am concerned that the reference voltage of Touchscreen Controller is as low as 1.8V(VDDA_ADC).

4.
Does a large position shift occur due to noise by using an LCD with high resolution?

Best Regards,
Shigehiro Tsuda

  • 0
    TI__Guru 64655 points
    1. The AM335x touch screen controller applies a potential to the resistive touch screen. The resistive touch screen acts like variable voltage divider that returns a voltage potential relative to the position touched. The ADC in the touch screen controller measures the voltage potential returned from the resistive touch screen. The ADC represents the measured voltage by returning a 12-bit digital value which allows a best case resolution of 4095.
    2. The resolution of the touch screen and display are not directly related. We do not have much experience implementing complete touch screen solutions in products, so I’m not able to address your question about successful implementations. The actual implementation of the touch screen and its performance in the environment which it is being used is the responsibility of the product developer. Therefore, you should carefully evaluate any touch solution to determine if it meets your product needs as part of the design process. The AM335x GP EVM has a resistive touch screen on it, so you could evaluate its performance to see this example meets your needs.
    3. As mentioned above, the resolution to the display is not directly related to resolution of the touch screen. The 1.8V potential applied to the resistive touch screen is also used as the ADC reference where this range of input voltage is resolved into one of 4095 values.
    4. There are many system level variables which may reduce the actual touch resolution. Noise is one of these system variables and may require software post processing to provide a good user experience.

    Regards,
    Paul

  • 0 in reply to peaves
    Mastermind 9490 points
    Hi Paul,

    Thank you for quick reply and detailed explanation.
    I understood that there is no information on the results of resolution and the resolution of the touch screen and display are not directly related.
    I recommended to our customer to evaluate them thoroughly using AM335 x GP EVM etc.

    Best Regards,
    Shigehiro Tsuda