TSC2017 Touch screen invalid Data in Windows embedded compact 7

Hi Aju,

I couldn't find any similar issue in my office with my TSC2017 bench platform.

Could you show me the circuits around the TSC2017? Besides, it is better to show me more code from your windows driver, such as how you send commands to the TSC2017, read coordinates back from the TSC20017 and the interrupt handling routine.

Andy

Hi Andy,

Thanks for the reply.

Please find the zip file which contain the touch circuits and wince touch driver code.1651.Code_Schematics.rar

In driver code,bsptouch.c is the lower level driver which contain the i2c read from touch controller.

tchstreampdd.cpp contain the PDDTouchIST which read the xy coordinates and convert the coordinates to samples and pass to mdd

Please give the solution for the issue

Hi Aju,

I just took a look at the schematic and I don't think I can find any issue. I will continue to review the driver code.

Andy

Hi Andy,

Thanks for your support.

If put finger on the touch screen and hold steady,we cannot find a mismatch data.

When release the finger,got mismatch data.

This mismatch data only happen at last coordinates

Please help to get  a solve issue

Hi Aju,

I think this issue happens when the finger is almost off but your Windows driver is still trying to read coordinates from tsc2017.  

How do you determine that the finger is still on or off in your driver? I didn't find any related code in the source files you sent to me.  

Basically, two method are available in the Linux / Windows driver.  a) Pressure value;  b) /PENIRQ. When /PENIRQ becomes high from low, it means the finger is off. I recommend the second method, which is more reliable.    

Andy

Hi Andy,

Thanks for the quick response.

From the TSC2017 datasheet, Our understanding that when finger is touched,PENIRQ goes HIGH to LOW.And PENIRQ is low state when finger is hold steady on the touch screen. When the finger is removed PENIRQ goes to LOW to HIGH

But from  your point,PENIRQ becomes HIGH to LOW when finger is off.

Can you please give a clarification on this point?

One more point,Our touch screen are less sensitive especially at the corners of the screen.How we can improve the sensitivity

Please reply

Hi Andy,

Thanks for the communication.

As you say, data mismatch issue happen when the finger is almost off but your Windows driver is still trying to read coordinates from tsc2017.  

Going through the windows driver driver code(already sent), the coordinates from touch controller are passed to MDD layer along with flag information.

When finger is touched ,winCE touch driver update touchsamplevalidflag=1 and Touchsampledownflag =1(in bsptouch.c) and this info is passed to MDD along with coordinates.

When finger is removed(in this case,got mismatch data coordinate from touch controller), winCE touch driver update touchsamplevalidflag=1 and Touchsampledownflag =0 and this info is passed to MDD along with coordinates.

Our doubt is that is this flag information is enough for MDD layer to remove the mismatch coordinate data from touch controller(When the finger is off)

Or we need to clear touchsamplevalidflag along with Touchsampledownflag.

Please help to solve the issue

Hi Aju,

I took a close look at the code you sent to me. I don't have right hardware to run this code, so I have to guess what might be the cause.

Below is some code I found inside the function BSPTouchGetSample() in bsptouch.c.
I think this code is used to determine whether the finger is still on or just off.
DDKGpioReadDataPin(DDK_GPIO_PORT1, 0, &isTouchUp);
if (isTouchUp)
{
StateFlags &= ~(TouchSampleDownFlag);
}

// Tell upper layers that this attempt was valid
StateFlags |= TouchSampleValidFlag;

Just before this code, both x&y coordinates are read from TSC2017 via i2c.

I suggest you implement the code this way:
a) Put the code above at the beginning of BSPTouchGetSample(). So, first you have to double check whether the finger is still on or not.
b) If the finger is still on, then read x&y coordinates are read from TSC2017. If not, set the correct flags and tell the MDD to do the right thing.

To further prove my idea, here is some code from the TSC2017 Linux driver. The code below first tries to determine whether the finger is off. If not, then now it is OK to read the coordinates.

if (ts->get_pendown_state) {
if (unlikely(!ts->get_pendown_state())) {
tsc2017_send_up_event(ts);
ts->pendown = false;
goto out;
}

dev_dbg(&ts->client->dev, "pen is still down\n");
}

tsc2017_read_values(ts, &tc);



Andy