CRTouch not responding, I2C to K70

[Larry5335]

Customer is having an issue where communication between a K70 and a CRTouch chip on the same board always works, but the CRTouch controller does NOT respond to a touch.

The details of the design are:

using MQX 4.0.2.1, I2C, eGUI driver. We have a task which handles eGUI (graphics and touch). We call eGUI’s Poll function every 20 mSec

The hardware uses the I2C bus from the K70 and a copy of the schematics from the TWR-LCD-RGB.

More details on the failure:

We are always able to communicate with the CR Touch IC via I2C. It is not an I2C, communications, or driver issue. What happens is that at some random point, the CR Touch IC will no longer report a touch screen press. When this occurs, touching the screen never sets the RTSRDY bit (or any other bit) in the Resistive Touch Status register 1. We can still communicate with the IC and the IC reports back status 1 register as 0x00 and reports back the same X and Y no matter what. If we reset just the IC (and not the rest of the board), it begins to function normally again. We have verified the communications with a logic analyzer and every command sent is responded to properly by the IC.

The frequency of the failure is rare:

We have 8 units that have been running since Saturday with no issue. 

Since it is so random, we have only seen the issue on a few units. It is impossible to give a good answer because a unit can run weeks without exhibiting the behavior.

Are there any known issues similar to this or known conditions that can cause the CRTouch to not respond to a touch?

[Peter_649]

Hello everybody,

we see both failures.

The first failure is the same as above. The CRTOUCH responds to I2C commands but a touch press is not recognized. The failure disappears after a CRTOUCH reset.

The second failure is that there are few devices responding with a permanent press after reset. The failure persists. It seems that the CRTOUCH controller is defective. The failure is very, very rare and occurs after some month.

Does anyone has an explanation and solution for the first failure?

Best Regards

Peter

[Larry5335]

Customer can duplicate the above problem on a K70 TWR with the TWR-LCD-RGB.

. I decided to run some code on the K70 tower with the LCD-RGB add-on. I ran the WVSM2 code on it.  I wrote the graphics and touch driver from scratch for this project. Still using MQX. I just got the CR touch IC to fail.

 This time, after about 10 minutes of operation, the CR touch IC always reports that the screen is pressed and the coordinates are the same. The RTST bit is always set.See first attachment labeled Regs.

The failure is the opposite of what occurs on WiCap where it never reports a press. This failure always reports a press.

I took some screen shots of the touch screen line Y+ using an oscilloscope. During normal operation, the line looks like this:

You can see the pulses when power is removed from the touch screen film and you can see 2 presses of the screen.

However, when the failure occurred on the K70 tower, it now looks like this:

You can see that after the failure, the CR touch IC is no longer scanning the touch screen.

[david_diaz]

Hello Larry,

Thank you very much for writing.

Definitely, this is a weird situation. I had never been faced with such an issue before using the CRTouch.

Based on your detailed description, indeed, it seems that the issue is related with the CRTouch platform.

In this case, I highly recommend to contact your NXP representative or your Local Distributor in order to initiate a CQI.

Please let me know if you experience any difficulty during this process.

Have a great day.

David Diaz.