Power & Source of Big Ideas

Flicker on eDP display running Android 8.1

Moderators: chensy, FATechsupport

Anyone else running the T4 with Android 8.1?

I am seeing flickering on the video after a certain time and seems to correspond with the display timeout but not always.

It's not a power issue as I have a bench supply running it under test with 12V and 600mA being drawn and with the power supply set for max 3000mA so plenty of power available.

If I press the power button to switch it off and then back on a few seconds later, the flickering has stopped.

Mine does that as well. Bring it down to 50% brightness and see if it still does it. It could be a underspec'd set of caps or something else circuitry-related.

I'm not suggesting that's a fix - only a reference to make sure we're on the same page.
I've dropped it to 60% and I'll leave it running and see if it happens again but usually the display has already dimmed at the point where it starts to flicker.

The eDP HD702 is the exact same LCD panel and touch as the RGB input HD702 but without the RGB to LVDS IC as it drives the LVDS directly.

Looking at the schematic, the LED driver has a 1uF cap on the output of the switching IC on the HD702 and a 4.7uF cap on the eDP version but the rest of the circuit is the same.

I have used over 10 of the HD702 displays without any issues with flickering when using with the Nano PC T3 Plus.
I left it at 60% for over 3 hours and no flickering was detected. I then bumped the brightness to 100% and it started to flicker within a few minutes. I dropped it down to 80 and the display is stable again. Just to be sure I bumped it back up to 100% and after a short time, it started to flickering again.

Dropping to 90% and it still seems to work and no flickering. 95% seems to give flickering too. You can't' see much difference between 90% and 100% anyway, so I can hopefully make some modifications to the Android source to limit the max brightness to whatever 90% is.

Also, need to email FriendlyArm support to ask if they are aware of this issue.

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