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Multitouch Controller TSC2020

Joemir Lopez
Prodigy 135 points


Hi All,

Good day!

Currently, we had a Multitouch Screen Controller design using a two(2)-TSC2020 for 12x20 Touch Screen LCD. We use the dual interleave technique using 2-to-1 MUX switches (TS3A44159RSVR) in order to cater the 12x20 LCD since the 2 TSC2020 can only handle a 6x10 LCD. Now, we have problems when more than 3 or more touches on the screen, the response is quiet slow and often some touches were not detected at all. Any thoughts on how we can improve the hardware in such a way that we can improve its response/sensitivity. Appreciate your help and kind support. I will attached the schematic for your reference.8004.TI_MULTITOUCH_SCHEMATICS_TOUCH_REV1_0802012.pdf

Thanks,

Joemir

  • 0
    TI__Genius 9725 points

    Hello Joemir,

    We had used a TSC2020 to control a 12x20 panel and did not experience the speed problem you have.

    I need more time to look into your schematic, and will get back to you as soon as I may. Also, it could be more helpful if you send me (w-fang1@ti.com) the related SW routines and/or description.

    Best regards,
    Wendy F.

  • 0 in reply to Wendy Fang
    Prodigy 135 points

    Hi Wendy,

    Thank you very for your support. I already gave you an email with schematic attachement.

    Hope to hear from you the soonest.

    Thanks,

    Joemir

  • 0
    TI__Genius 9725 points

    Hi Joemir,

    There are several places that could effect TSC2020 touch data throughout rate --

    (1) TSC2020 touch data converting speed: The more the scanned channels are, the slower a full panel scan needs to be. However, TSC2020's ADC speed is very high for touch applications and also, as I mentioned before, we had used a TSC2020 to control a 12x20 panel with very reasonable response speed. I may calculate the touch data throughout rate specifically for your system if you provide me the TSC2020 setup values. 

    (2) TSC2020 and host processor interface speed: it can be the main reason because: the more touches on the touch panel, the more touch data have to be moved from the TSC to the host.  Does the host read data length depends on the number of touches? What is your I2C speed mode?

    (3) At any time moment, if there are 4 simultaneous touches that forms a straight-rectangle, the data reading from the corresponding 4 segments will be outside their ranges, as described in the email I sent to you this morning. If the host processor simply throw away such data, there will be no response during the period, and results in slower response.

    Hope the above helps and please feel free to ask as you need!

    Best regards,
    Wendy F.