My BeagleY-AI has the suggested power supply (65W) and is functioning as I would imagine it should when connect via ssh, except when plugging in an external monitor to the miniHDMI port the screen always flashes intermittently. I have tested with multiple monitors, the latest being the HP25es. Is there any reason this could be happening?
Thanks!
My first thought would be a cable fault. Are you able to use this cable with some other device? Is the cable seated properly?
What does journalctl report?
I thought the issue was the cable as well, just got a new one and the issue remains the same. (both were seated properly)
What should I be looking for when running journalctl? It reports too many lines to copy all at once.
I don’t know if it’s worth noting but it seems that when the board runs more computationally intensive tasks the screen flashes much more frequently but remains black much longer.
Try a different SD, out of the box my first board is flaky. It came with a funky colored screen then it would not boot after it was warmed up. Ordered a second board, it has been doing much better. If that does not clear it up might try another board.
There’s a few of ways to monitor the journal:
journalctl -f will print journal entries to the screen as they occur. Run this in a terminal. Then, when a flash happens, see whether any entries look suspicious.
journalctl -en20 can be used immediately after a flash has happened and will print the last 20 (in this case) entries.
Just look for anything that might be relevant to your issue.
Pretty much the same issue.
I’m using a usual consumer grade TV (Vizio D series 24" and Vizio V series 4K). And while on a smaller FHD TV is “blinks” or “flashes” sporadically (maybe once a several minutes), than on a bigger TV it is happening very often (once per 10-15 seconds)
The cable I’m using is “RPI white” cable, and while using this exact cable with RPI - the issue is not happening at all, so I assume the cable is fine.
But anyways I bought another cable, and the issue is exactly same rate on the same devices…
In journal literally nothing.
beagley-ai
Maybe small update from my side. In the kernel log messages of the displaying device I saw multiple type of errors, but in most of the cases when flashing is happening following errors are displayed:
HDMI 14 Active cable error happened, WB error: 0, 0, 0 port 2
...
HDMI Port 2 TMDS error status is 08
...
And than renegotiation is happening and image on a screen restores.
Interesting fact is if I AT FIRST connect RPI, and than reconnect BeagleY, flashing is not happening and no HDMI/TMDS errors present in kernel logs on a receiving device…
Also, as I mentioned before, the issue is not happening at all with RPi on the same HW setup (TV, cable, power source, even board location on the table 
)
Found a discussion and proposed solution in the following issue: DSS to HDMI chip debug problem with PCLK and porch configuration (#58) · Issues · BeagleY-AI / BeagleY-AI · GitLab