HTT50G Flickering under Windows and Linux

[cosmogramma]

Hi,

I have recently purchased a HTT50G-TTPC-BLM-B0-H5-CH-V5 from Digikey

Under both Windows 10 (intel graphics), and on a Raspberry Pi 4 (running both latest and legacy rasbian) the display constantly flickers, implying the timing is wrong.

While it is specified as working at 60Hz, if I read and decode the EDID data (e.g. using https://people.freedesktop.org/~imirkin/edid-decode/), it actually reports itself as being 67.73Hz

On Windows, I cannot change the timing from this (presumably incorrect) value, even if I tick "show modes not supported" in display adaptor properties.

Under linux, I have tried the following. All show the same flickering:

• Running a clean install of the latest Raspberry Pi OS, and letting it autodetect
• Changing the kernel command line on latest raspi OS, which does not support setting resolutions in config.txt, appending

  Code: Select all

  video=HDMI-A-1:800x480M@60 

  With this, I get this output at boot, which looks suspicious

  Code: Select all

  vc4-drm gpu: [drm] User-defined mode not supported: "800x480": 60 29605 800 816 896 992 480 481 484 497 0x20 0x6 [\code]
  
  [*] Running legacy Raspberry Pi OS, and putting in the recommended settings (page 9 of the user manual) into boot/config.txt
  [*] Forcing 60Hz (well, 58.91) with [url=https://wiki.st.com/stm32mpu/wiki/DRM_KMS_overview#modetest_-28DRM-2FKMS_test_tool-29]modetest[/url],  [code] sudo modetest -M vc4 -s 32@96:800x480-58.91 

• Forcing 67Hz (the other supported mode) with

  Code: Select all

   sudo modetest -M vc4 -s 32@96:800x480-67.73 

Therefore, I have the following questions

• What are the full timing settings (including blanking) for this LCD?
• Why does the EDID report the refresh rate as 67.7Hz, when the docs say 60Hz?
• Is there a known working set of settings for the raspberry pi 4?

[Raquel]

Hello Chris,

Thank you for posting on the forum.

We also received your query via email.
We will respond via email and update here when we get to the resolution of the issue.

Thank you,
Raquel

[Raquel]

Update: Flickering was rectified by powering the HTT50G separately using the barrel jack (separate power source, not from USB).