Screen re-calibration?

[canderson]

Since your firmware is prior to v8.051, you will need to create a file called calib.txt (not cal.txt, which applies only to 8.051 and beyond).
Also, since you are pre-8.051, your data format should be MaxX MinX MinY MaxY and it appears to be so.
So you've got the right file and the right format. Now you're down to the tricky part:

If your up/down is OK, then leave the Y value alone, and focus on "X". With the following in mind, you may need to increase either MinX or increase both MinX and MaxX.

MaxX Affects the LEFT edge of the screen
Increase MaxX = Touch point moves further to the RIGHT of where touched
Decrease MaxX = Touch point moves further to the LEFT of where touched

MinX Affects the RIGHT edge of the screen
Increase MinX = Touch point moves further to the RIGHT of where touched
Decrease MinX = Touch point moves further to the LEFT of where touched

 

[RobH079]

Hi canderson thanks for the quick reply, I think the screen on this is too far out of whack to recalibrate or I'm doing something wrong. I've tried increasing both values on the X axis but since MaxX is already at 910 I don't really have a lot of room to increase it by.

I've tried increasing MinX in increments of 20 right up to over 500 but no change to the screen behaviour. I'm going to try it again on a different computer just to rule out any funny business but I'm not holding my breath.

 

[canderson]

It could be that the resistivity has drifted too far to fall within the calibration ability of the file, but try working with MinX to see if you can get any real movement.

 

[RobH079]

I've tried heaps of different combinations for both MinX and MaxX, with no change but with one exception: when I make MinX larger than MaxX I get the same problem but with the opposite edge of the screen.

Eg: 505 500 116 875 doesn't change anything, no matter where I press it activates the left border of the screen
500 505 116 875 switches the problem to the right border of the screen

Short of going through thousands of different combinations I don't know how to proceed, there doesn't seem to be any in-between.

 

[RobH079]

I've also noticed that if I change the Y values and run a stylus over the screen erratically, the screen can sometimes be overwhelmed and then functions almost perfectly until the reset button is pressed, then it reverts back to the old problem. It's almost like a short/voltage change in the screen is causing it to go haywire. I've only managed to get it to do this once.

 

[canderson]

Does sound like your touchscreen is shot. There are replacements available for it out there aplenty, but I wonder if it's worth it for a ONE 3rd.

 

[RobH079]

Agreed, after heaps of mucking around that's the conclusion I've come to. I've ordered a cheapo digitizer replacement from eBay so I'll see if that changes anything once it arrives. Thanks heaps for all your help with this, I will keep you posted on whether I manage to fix it!

 

[canderson]

Be sure to keep a link to this thread. You'll may again need to use a calibration file. The original numbers in your device are stored in an area where they can't be changed (that's why you have to override it with the calibration file) and won't necessarily give you good results with a different screen. Those numbers are tailored to the screen that is originally fitted to the device.

 

[Greg40]

Hello all. I have a problem with the device TT GO920T. The device lay in the closet for several months, the battery has been discharged to zero. After charging and restarting, TT does not respond to touch at all. I tried to replace the cal.txt file in various ways, unfortunately with no result. Can I count on help? Original file Touchscreen calib date: 94 935 140 852 Thank you.

 

[canderson]

Best give that little button in the bottom of the device a gentle poke with a paperclip or similar for a few seconds and hope for the best (that produces a hard reset).
Sitting in the closet for a while isn't going to throw the calibration so far off that the touch screen ceases to work at all. It's beyond a calibration problem of some sort. The calibration file just adds a bit of offset to the device's current voltages vs. touch position that change a bit as a function of drifting resistance over time.

 

[Greg40]

Thank you for your reply friend canderson. The problem is that I have already tried this solution and unfortunately it does not bring any result. Second thing, in Navcore I do not see any file responsible for screen calibration. Should he be there?
I also tried to start the device with another navcore from the SD card, also without changes. I also used the cal.txt file in various configurations. The device behaves as if the file was not there at all.
Clearing the memory with the application of "clear flash" unfortunately did not help either.

 

[canderson]

No. The original data is embedded in an area of memory where it is not seen or adjusted. That is what appears on the screen as the 'default' value when you go to the black and white diagnostic screen.
From the factory, no unit has a calibration file. Those are only added by users after the fact if needed.
If there is zero response to the screen, no amount of fiddling with calibration files is going to help.

 

[Greg40]

I understand that navigation can not be fixed anymore?

 

[canderson]

Since we do not know if the failure is the touch panel or the motherboard, there isn't an easy solution. If we were sure that it was the touch panel, those are available to replace at a reasonable cost. But if you get one and it turns out that the panel was not bad, you are out that much money.

 

[Greg40]

It's hard, just put the device back into the closet, or sell it to someone else. Thank you for your interest in the topic.

 

[M.K.W]

I know this is an older thread. I just wanted to say thank you to oldfogy and canderson. I have an old 930 than the screen slowly went out of calibration. It was to the point that I couldn't use it anymore. I know it's an EOL device but I still use it for local travel. Mainly red light cameras and speed alerts. Following the instructions in the thread I was able to recalibrate the screen and it's like new again. Back in November of 2015 I had a xxl540 that the screen froze up on. Canderson worked patiently we me to try and resolve the problem. I appreciate the work of these two and all the others who contributed to Tomtom forums

 

[canderson]

Just back in the country again and hunkering down. Really glad our old conversations here are still helping!

 

[Dragao]

Hi all,
I have made some progress following these tips.. But....
I have only half a screen that works.. that means.
I can operate the lower half of the options I can not get any higher. I do think the touchscreen is in working order as I can use the upper half (it just is selecting the lower items) I have tried changing the setting in the cal.txt file but It's unclear to me to know in which direction I have to move.

original settings: 94 940 159 853
file settings: 940 94 723 29
With the file setting I can correctly select the lower options. (which was the initial problem, I was half way screen and then selecting lowest option (like connection to the computer option)

Any insight is appreciated

Hmm I just made a leap of faith.. changed my file to : 940 94 373 29
I made progress I can operated the first row.. but it does not make sense to me..

Still can operate the very top of the screen.. (like when switches maps, can't select the upper map)

 

[canderson]

If you are getting correct responses (pushes do the right things) on half the screen, and no response on the other half, then the calibration isn't the issue. The calibration impacts the entire screen view vs. button press positions. It does sound as though your screen has issues.
You can pick up a new LCD + Digitizer for very little money on a variety of sites, including eBay.
I believe this is an example >> https://www.ebay.com/itm/For-4-3-To...play-Screen-Panel-Touch-Digitize/193022671108

 

[Behemot]

Got ancient XL N14644/Canada 310 which recently started drifting left and upwards to the state that I can no longer press any button in the rigt-lower corner. Ttgo.bif shows ApplicationVersionVersionNumber=8083 so its 8.083. Made cal.txt coded in UTF-8 without BOM, placed the original values in and started editing, does not seem it reacts to ANYTHING I put in there. File attached, do not see any problems in that. Any idea?