Display "flash down" with imx8qm

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Display "flash down" with imx8qm

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Contributor I

Hi, I'm going to describe a problem I'm encountering and I can't exactly understand which can be the cause.

I'm evaluating diffent board for a new project, in particoular I'm evaluating a board performing iMX8M and two boards performing iMX8QM.

Every board should be connected to a 15.6 dual-channel LVDS (Ampire AM-19201080D1TZQW-TA8H).

Using iMX8QM I noticed that when full white color should be shown on the display, the display seems to turn off with a violent flash (you can see it in the attachments). After that moment the display seems to be dead, I can only manage LED brightness thanks to a PWM.

This violent shout down is only about the LVDS, the rest of the system is correcly up, I can use the console, I can start Wi-Fi and I can start applications.

This issue occur at every level: u-boot, Kernel, file system. I don't think it is a problem about the drivers, since if I use a different color image (for example full blue 0x0000ff) the display works fine.

In short words, when the display has to show full white images, it seems to "shut down"

It happens only with this particoular dispaly (I tested 3 unit of them and I get the issue on every one of them) and if I use different compatible display I don't get this issue.

Using iMX8M I don't get this issue, but this last system mounts a LVDS bridge and the display is not magaged "directly" from the micro.

I tested the same application, the same color combination with iMX8QM but using HDMI output ad a HDMI-LVDS conversion board.

In this case the problem does not occur. I tested it for a very long time.

I'm asking here because after working on this problem with board producer we didn't find a solution (maybe in the next days we will find one).

I also tried to give the display a stand alone 12V but the problem persists.

Did you ever see something like that?

I honestly don't think it is about the board, since I reach the same problem on both of them (they are two board of two different brand).

Best regards,

Andrea

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5 Replies

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Contributor I

Hi Andrea,

Had similar issue and it came down to 3v3 supply drop on white image. Cable you're using is probably 40AWG and causes voltage drop. Try adding external wire on 3v3 in parallel and see if that fixes your issue.

Regards,

Ivan

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Contributor I

Hi Ivan, sorry for my late answer.

Finally I get support from Display manufacturer and they told me they are going to replay a PCB on the display. 

With the new PCB I'll be able to use the display with no trouble.

Thanks everybody for your support.

Andrea

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54 Views
NXP TechSupport
NXP TechSupport

Hi Andrea

you are right, seems this is issue with that particular lcd, not processor.

In general one can try with latest i.MX8QM production revision starting with "M",

marking can be found in Table 2. i.MX 8QuadMax Orderable part numbers

i.MX 8QuadMax Automotive and Infotainment Applications Processors

and Linux 4.19.35_1.1.0 software found on

i.MX Software and Development Tools | NXP 

Best regards
igor
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Contributor I

Hi Igor,

Thanks for replying.

I think it could be because of this display, infact we already wrote to Ampire in order to investigate this problem,

but I would to go a bit deeper this issue with you.

Using an external bridge, as iMX8M board does, the problem doesn't exist, furthermore it doesn't exist using iMX8QM with hdmi output ad HDMI-LVDS convertion board.

It exists only when the LVDS is driven "directly" from the processor (correct?).

If the problem is in the display I would like to find it and manage a solution: do you think I can measure some significant parameter which allow me to know which is the origin of the problem?

Sorry if I'm not very technical in my description but I'm not very skilled in this fields.

Then, my processor Part Number is PIMX8QM6AVUFFAB on both systems we have in our Office.

Do you think I could make sense trying  4.19.35_1.1.0 also on this Part Number?

I'm asking since I think both the company who give us the boards are "in sync" with a older revision.

Thanks for your help,

Andrea

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54 Views
NXP TechSupport
NXP TechSupport

Hi Andrea

yes PIMX8QM6AVUFFAB can be used with  L4.19.35_1.1.0, please check it on

i.MX Software and Development Tools | NXP 

Best regards
igor

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