i.MX6UL Touch Screen detection

[yurirellosa]

Hello All

We are using a 4-wire Resistive Touch Screen and are looking for a way to detect if it is physically connected during device startup.

In the reference manual (Chapter 51 Touch Screen Controller), there is a detection mode and debug mode but I could not figure how to get them to work.

Is there already a guide for a way to go about implementing this?

(*On normal settings/operation, there is no problem in getting touch data)

Best Regards

Yuri

[yurirellosa]

Hello Arthur

Thank you the advice.

We will try implement the detection process with this method.

Best Regards

Yuri

[art · Accepted solution]

The TSC module of the i.MX6UL processor doesn't have any built-in physical touch screen connection detection feature. Since the TSC module operates in combination with ADC and actual measurements are performed by ADC, the possible method of implementing the touch screen connection detection function is to directly access the ADC (without using the TSC module), then apply some voltage (e.g. by enabling a built-in GPIO pull-up resistor of the corresponding ADC GPIO input) to one edge of each resistive plate of the touch screen and then measure the voltage on the other plate edge using ADC. If the touch screen connection is physically broken somewhere, some of the voltages will be absent.

Have a great day,
Artur

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[CarlosCasillas]

Hi Yuri,

You could refer to the Touch Screen Controller driver (tsc) for i.MX6UL processor. Please take a look at the following links:

Linux/drivers/input/touchscreen/imx6ul_tsc.c - Linux Cross Reference - Free Electrons

[PATCH 1/5] input: touchscreen: add imx6ul_tsc driver support http://lists.infradead.org/pipermail/linux-arm-kernel/2015-July/359604.html

[PATCH v3 1/5] input: touchscreen: add imx6ul_tsc driver support

Hope this will be useful for you.
Best regards!
/Carlos
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[yurirellosa]

Hello Carlos

Thank you for your response.

Just for clarification, we have no problem receiving/detecting Touch Data from the Touch Screen.

We are indeed using the same using the same "imx6ul_tsc.c" driver as the links.

The problem we have is how to implement detecting the Physical Connection of the Touch Screen.

Whether the device can be seen/detected or not by the CPU or OS (Linux OS in this case).

If you have information regarding this it would be really helpful.

Best Regards

Yuri