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+--- Thread: Touch wheel's not very sensitive, is that normal? (/showthread.php?tid=131)
Touch wheel's not very sensitive, is that normal? - Shiny! - 2025-02-04
Something I've noticed ever since getting my Tangara is that the touch wheel kinda requires me to smoosh my finger down on it to get it to work reliably, a lighter touch tends to be extremely unreliable at best, it's pretty physically uncomfortable to use like this so I'm wondering if something's up with my Tangara or if this is normal behavior, I've seen a friend on fedi also have this problem
Like I know the way it senses touch is really different than an iPod, but the same amount of pressure that makes that thing work fine gets almost no response from my Tangara (at least on the wheel, the center button seems somewhat more responsive)
I can't figure out if this is a software problem or a hardware problem (tbf I haven't taken it apart yet to check anything) so I'm posting it here in case any of you know anything
RE: Touch wheel's not very sensitive, is that normal? - ailurux - 2025-02-04
I find that the pressure makes less of a difference than the angle and surface area of the finger/thumb making contact. If you find yourself needing to apply a lot of pressure, it might be that you need to adjust the angle. Ie, the tip of an index finger pointed straight down is basically the worst case for it, and will require much more pressure to register the touch than using a flatter angle with the pad of one's finger or thumb. The touchwheel is capacitive, and not pressure sensitive, the reason pressure might make it seem more responsive is because when you press your finger into it, its got a larger surface area making contact than a light touch.
Of course if the sensitivity seems really off even with a flat touch, then it might be an issue with something else, so please let us know if the above tips help
RE: Touch wheel's not very sensitive, is that normal? - Shiny! - 2025-02-04
The advice does help, I'm usually trying to use the tip of my thumb (partly to avoid fat-fingering the center button), though I'm still finding the sensitivity rather low even if I use the pad of my thumb, I still have to press more than I'd like to get it to be reliable
I'm aware of it being capacitive (I remember reading your campaign update about that, pretty neat stuff), I guess I'm mainly wondering if it could be related to something like the distance between the touch wheel's cover and the PCB, but again I haven't yet had the chance to take it apart, I'm probably gonna wait to try that until I'm sure I won't need to send any more info about another issue over on the Codeberg heh
I'm noticing the top half seems less responsive than the bottom half, which could maybe support that idea? But it's kinda hard to say
Just makes me wonder though, is it possible to adjust the sensitivity of the touch sensing in the firmware? Like, somewhere in the code to mess with, that would be interesting for me to play around with
As for the iPod comparison again, I notice on mine (a b/w 4th gen for what it's worth) that its click wheel is very sensitive, I can sometimes get it to active without making a full touch, but in practice I don't think I've ever found accidental inputs to be a problem on there, so if I could get my Tangara to be close to that then that would be really nice
RE: Touch wheel's not very sensitive, is that normal? - ailurux - 2025-02-04
Quote:The advice does help, I'm usually trying to use the tip of my thumb (partly to avoid fat-fingering the center button), though I'm still finding the sensitivity rather low even if I use the pad of my thumb, I still have to press more than I'd like to get it to be reliable
We've recently merged a PR to make accidental centre button triggers less of an issue when scrolling (thanks again schrockwell!)
Quote:(I remember reading your campaign update about that, pretty neat stuff)
Aw thanks, I'm glad to hear it
Quote: I'm mainly wondering if it could be related to something like the distance between the touch wheel's cover and the PCB
It's possible, there is a bit of tape between the touch wheel cover and the PCB to help secure it, though we use a thin tape and put it in the "cat ears" corners to try minimise sensitivity loss. It's worth having a look if perhaps the tape is folded over itself making it a larger gap than it should be. Not all units got this tape though, so there's the possibility it's not there to begin with.
Quote:Just makes me wonder though, is it possible to adjust the sensitivity of the touch sensing in the firmware? Like, somewhere in the code to mess with, that would be interesting for me to play around with
We use a AT42QT2120 (data sheet can be found here: https://www.microchip.com/en-us/product/AT42QT2120) set to wheel mode. I'm not entirely sure if writing a lower threshold to the detect threshold register (5.16 in the datasheet) will affect the sensitivity when also set to wheel mode, but that is where I would start.
RE: Touch wheel's not very sensitive, is that normal? - ailurux - 2025-02-05
(2025-02-04, 10:29 PM)ailurux Wrote: We use a AT42QT2120 (data sheet can be found here: https://www.microchip.com/en-us/product/AT42QT2120) set to wheel mode. I'm not entirely sure if writing a lower threshold to the detect threshold register (5.16 in the datasheet) will affect the sensitivity when also set to wheel mode, but that is where I would start.
So I tried setting the detect threshold to 5 counts (default is 10) and it seems to make it more responsive. I can quite easily scroll with a finger tip with this change.
Code:
diff --git a/src/drivers/touchwheel.cpp b/src/drivers/touchwheel.cpp
index 402b839d..0c08b091 100644
--- a/src/drivers/touchwheel.cpp
+++ b/src/drivers/touchwheel.cpp
@@ -65,6 +65,11 @@ TouchWheel::TouchWheel() {
// so that the user's finger isn't calibrated away.
WriteRegister(Register::RECALIBRATION_DELAY, 0);
+ // Adjust sensitivity
+ WriteRegister(Register::DETECT_THRESHOLD_BASE + 0, 5);
+ WriteRegister(Register::DETECT_THRESHOLD_BASE + 1, 5);
+ WriteRegister(Register::DETECT_THRESHOLD_BASE + 2, 5);
+
WriteRegister(Register::CHARGE_TIME, 0x10);
// Unused extra keys. All disabled.I wonder if it might make it a bit too easy to trigger though, so maybe we want this to be configurable as a setting?
RE: Touch wheel's not very sensitive, is that normal? - Shiny! - 2025-02-05
Trying this change out myself, so far it's making a nice improvement, thanks!!
It's definitely an improvement over how it was before, though I still have the sensitivity difference between the top and bottom halves so I'll still probably have to open it up sometime to check thatFor now I'll keep it like this on my build, it's much more usable but still not sensitive enough to cause accidental inputs, I think having a setting for that would be very nice
I'll probably play around with some other numbers to see what I'd prefer most
RE: Touch wheel's not very sensitive, is that normal? - Construc_ - 2025-02-05
sensitivity options would be nice 🙏
i prefer a lighter touch and getting used to the tangara's requirements has been a learning curve for sure
RE: Touch wheel's not very sensitive, is that normal? - jfred - 2025-02-09
Just found this thread and I'm interested in sensitivity options as well! I might have to try out that patch, if it makes the touchwheel more usable with a fingertip that sounds very useful.
I also just had the idea recently of cutting a matte touchpad protector to size and putting it on top of the touch wheel cover, because my fingers were slightly sticking to its surface making it harder to scroll. That seems to help for me at least!