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Thread: Strange behaviour / slowdown issue

  1. #1

    Strange behaviour / slowdown issue

    Hello all,

    Just wanted to generally discuss a very odd problem that me and my friend have come across. I wanna underline that this is not a Teensy issue, more of a paranormal activity issue (lol).
    Both me and my friend have custom PCB's with Teensy Micromods on them, we both have the exact same PCB which we have designed together. They're solid and as far as we know they work. Or atleast my friends one work perfectly over and over.

    The specific issue is that I get "lag" or rather slowdown. More specifically on the touch glass. We've tied the backlight of the LCD to the touch of the glass to see the delay. On my friends end it's instant, like light speed instant. When he touches the glass the backlight is on. It's to the point where it's very satisfying to watch.
    On my end, with the same PCB, display and now even with his code just to rule that out. Mine is almost 0.5 seconds in delay when I touch. I've gone so far to replace components, I've tested 3 brand new Micromods, new display with new touchglass, new connectors. I've also tried other powersources, other cables, I even flashed from my laptop instead of my main PC. We're at the point where things don't make sense anymore. Is there a ghost in my house messing with me? The only other thing I can think of is that the PCB is faulty, perhaps bad grounding at some point(?).

    EDIT: Some more info that might be good to have: i2c touch glass with FT6236 driver, using 2x 3.3k resistors for the i2c bus. Nothing else is on the i2c bus (no other devices or sensors).

    I basically just wanted to share this very strange problem and perhaps get some ideas from you guys. Maybe one of you have gone down this road before?

    Cheers!
    Last edited by Dogbone06; 11-14-2021 at 11:47 AM.

  2. #2
    Senior Member
    Join Date
    Jun 2013
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    415
    Doesn't capacitive touch depend on the grounding. A device connected of a battery powered laptop might perform different to one that is connected to a well grounded PC. Humidity might also be a factor. Not sure if these are your problems, but something to think about.

  3. #3
    Quote Originally Posted by yeahtuna View Post
    Doesn't capacitive touch depend on the grounding. A device connected of a battery powered laptop might perform different to one that is connected to a well grounded PC. Humidity might also be a factor. Not sure if these are your problems, but something to think about.
    Might be so. Alltho I did connect it to my laptop, PC and also a wall USB outlet. None worked.
    Interesting part is that I just finished soldering another board and now I have no delay, with the same Micromod. Backlight is now instant when I touch the glass.
    Something is wrong with the old board, I just don't know what. I'd like to learn what the issue is to add that to my experience.

  4. #4
    Little update. I soldered a brand new board and hooked it up. I didn't get a picture yet because the IM0, IM1, IM2 pins I didn't solder. So I started it up and tested again, now it's all instant when I touch the screen I get backlight. All well and good.
    Soldered up the IM pins so that the display goes in the correct mode. And boom, issue is still here. So basically when I have picture the touch slows down.

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