Connect capacitive touch display to colibri imx7 on iris with boot2qt image

Technical Support
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1

Hello,

I have a Colibri iMX7 with the boot2qt image (5.15.2). I had the toradex 7" resistive touch display , which worked fine, but now I need to replace the resistive touch display with a capacitive touch display.

I have connected the toradex 7" capacitive touch display with the DSI cable and the capactive touch cable as per the instructions.

  • I have set the the vidargs via uboot

    'video=mxsfb:800x480M-16@60,pixclockpol=1'```
(which were the same as for the
resistive touch display) but the
display does not display anything.

  • I tried to flip the DSI cable because
    the instructions are not clear on
    this (there is no picture for the
    IRIS v2.0 and the DSI connector is on
    the opposite side of the PCB) but
    there is no image displayed.

  • I also
    tried with Toradex Easy Installer and
    Torizon images instead of the boot2qt image, but that did not help either.

  • I am not using the capacitive display adapter, because
    the documentation says it is not
    necessary vor IRIS v2.0

  • Also I have not changed the device
    tree, as this is only required when
    the capactitve adapter is used.

Should the capacitive touch display work on the Colibri imx7 with IRISv2 ?

Thanks,
Michael

2

Are you talking about this Toradex 7" capacitive display ? It doesn’t have a DSI interface. It has the same parallel RGB LCD interface though 40 pin FFC cable as you 7" display. Plus it has a small 10 pin FFC connector for touch controller.

If you setup works OK with 7" resistive touch and you connected 40pin FFC cable properly - you should see a picture on your new screen. But to you still have to update your Device Tree to make touch work.

3

Thank you for confirming that the display should work with the same setup as the resistive display.

There is no picture with the capacitive display (just white with dark stripes). Please see the attached image.

If this is not a driver/configuration error, could the display be damaged?

2715-toradex-capacitive-display.jpg
2715-toradex-capacitive-display.jpg985×985 265 KB

4

Sorry, but your picture is not available. Could you reload it? Does it show how FFC cable is connected?

5

alt text

6

Display cable connection looks OK. Could you try to load Toradex Easy Installer over USB OTG? The 7" capacitive touch screen definitely work out of box with Toradex Easy Installer (without touch though).

7

I tried that. I first installed Toradex Easy Installer with the Resistive Screen, then tried with the Capacitive Screen. Then installed Torizon from Toradex Easy Installer with the Resistive Screen, then tried the Capacitive Screen. The result was always the same as above. The capacitive screen did only show lines.

8

So I think either screen or FCC cable is defective. Do you have another screen or cable to test?