STM CircleOS forum / Touch Screen calibration

samarkh · 2009-01-23 13:26:25

Has anyone better 'touch screen calibration' code they would like to share?

Yours Simon M.

Socrates · 2009-02-18 09:18:07

Hello Simon,

so far as I can see is the touchscreen calibration not working very well. So I'm looking to for another calibration procedure! Does anyone understand the current calibration?

samarkh · 2009-02-18 10:00:06

Hi Socrates,
I'm glad to see that someone agrees with me.
I can only comment on the Primer2, but when using the stylus to select an application, I have to select the one below!
As for horizontal that is many mm out on one side, but almost spot on on the other.

Yours Simon M.

Francis · 2009-02-18 10:03:42

Simon :
when using the stylus to select an application, I have to select the one below

I believe that it's not a calibration problem, but a bug in the list managementt. The selection is correct but sometimes, the wrong application is launched. It depends on what happened before...
This bug will be fixed in CircleOS 3.6.

samarkh · 2009-02-18 11:52:57

Thanks for the update Francis, but what about the Left-Right error?

Yours Simon M

Francis · 2009-02-18 12:43:09

I guesrs that we could reduce it... I will publish today a document that explains how we proceed. I believe that it is possible to have better results.

samarkh · 2009-02-18 13:33:08

Many Thanks for that Francis, it would help me a lot because I'm hoping to make a simple on screen keyboard.

Yours Simon M.

Socrates · 2009-02-24 10:05:59

Hello all,

i meanwhile figured out that the calibration "offset" is not due to a list functinality! I'm using the touch screen in a complete different application on the primer 2 (without list and circle os) and i'm getting the same offsets after calibration!
Where can i find the document mentioned above?

Francis · 2009-02-24 13:03:31

Some information about the touchscreen calibration is included into the document 'evolution from version 2 to version 3' (see the CircleOS 3.5 project).

klausr · 2009-06-01 14:34:24

Hello,

I am developing a program which depends on a good calibrated touch screen.
It seems that the touchscreen calibration is somewhat bad in OS 3.7. I wrote
a small tool to show that (project TouchScreenTest). Even without any motion with my hand the drawn lines are moving randomly around, sometimes up to 5-8 pixels away of the typed position (I used my Tungsten C stylus). My program GUI requires that one is able to hit at least a 7x10 pixel rect safely.

Can we expect a good working touchscreen calibration in OS 3.8? Will OS3.8 be released before ending of the contest? I really thinks this belongs to the OS. If not, is there some example code so that i can do the calibration on my own? Or is it simply not possible with that kind of touchscreen used.

-Klaus

Francis · 2009-06-02 07:18:11

We don't plan to improve the calibration before the contest. If you can improve it -without any major change- we will update 3.71 to 3.72.

KPexEA · 2009-06-17 21:32:58

There is a page here that has a very good writeup on Touchscreen calibration and source code to implement it.

It looks much more comprehensive than the current calibration.

http://www.embedded.com/story/OEG20020529S0046

ftp://ftp.embedded.com/pub/2002/06vidales/

Comments??
Kevin

xbapx · 2009-07-07 09:45:44

The page mentioned is really good and the explanation is logical so far. But how is it possible to get the following lines, especially the values:

Y = ( (570*Y) - (15*T) -19400 ) / 1000;
X = ( (490*X) + (170*Y) -15157 ) / 1000; //see at touchscreen.h

Thanks

Francis · 2009-07-07 14:13:14

FYI, we are currently trying to improve the touchscreen accuracy... Thanks for the link.

semsem · 2009-07-11 13:49:38

In Micro Windows i have implemented the calibration algorithim mentioned in the link.This calibration can be enabled or disabled from the Config.h file which has all the windows configuration. Feel free to use it and even copy it.

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