From time to time, the HDMI display gets disturbed, but not always in the same way. Most of the time, the pattern is a blinking pinkish display with pixel noise, but other times it is only pixel noise (swarm of white dots), as if the HDMI signal were disturbed or as if the EDID were misinterpreted. This lasts a few minutes, then everything goes back to normal. This is random, but it seems to mostly occur when the board is cold.
Issue observed with:
several VIM boards
Since this occurs for 1080p60, I am certain this is not caused by the HDMI cable. I don’t know if this is caused by the VIM or by the TV, possibly not supporting some EMC stress. Has anyone already observed this?
Have you tried with another HDMI output device with the same HDMI cable & TV monitor?
And how many VIM boards you tested? I’m not sure whether HDMI compatiable issue for some monitors, but Amlogic SoCs should be good compatiable for this, is it possiable for you to take a simple video include the VIM board, HDMI cable, Monitor, Adapter and the issues, so our team and I can better understand the issues better.
I will keep follow up the issues, kindly keep update.
Yes, and it seems to work, but the issue occurs randomly only about 2 or 3 times a week during a few minutes, so it’s hard to know for sure whether or not a given configuration has this issue because a very long test time is required.
I have observed this issue with at least 3 boards.
I will try, but the issue is rare and it lasts only a few minutes, so it may take a while before I can shoot a video.
In this video, the ExoPlayer demo application is displaying a paused video, so the image is supposed to be still. However, it blinks between the normal image, green, and black, as if the HDMI signal were periodically lost then recovered. And when the normal image is displayed, there are many whitish dots of different sizes blinking over it (visible from time to time between 0:00:04 and 0:00:06 in the video; much easier to discern on the screen with your eyes than in this video), as if the HDMI signal were disturbed.
The issue recorded in this video started randomly and lasted a few tens of minutes. Displaying something else or switching to another application had no effect on the issue.
TV: Panasonic TX-40DX700F
HDMI: 4Kp60 HDR
things connected to the VIM: Khadas power supply on USB Type-C, TV on HDMI, Ethernet, USB flash drive
We got several VIM1s experiencing this issue in the last batch that we purchased. So it happens with several VIMs, but not all. For the affected VIMs, it happens with many HDMI cables and monitors.
Slightly moving the HDMI plug inside the receptacle makes the issue appear or disappear. Therefore, it looks more like an HDMI connector issue. There is sometimes too much mechanical play, so the electrical contacts may become loose by barely touching or moving the cable, which corrupts the HDMI signals.