I don’t have a RPI3 available as of yet? Does Seeed have a RPI4 to test with? How do you explain the major flickering on several different PC’s when first powering up - then flickering gradually goes away over time (like within 15min until it stops completely)?
Given my configuration:
RPI4B 4G (running the ‘2020-02-13-raspbian-buster-full’ image)
RPI4 Connector HDMI0: 7" 1024x600 IPS LCD, rotated Left
RPI4 Connector HDMI1: 5" 720x1280 IPS LCD, rotated Right (Seeed SKU 104990442)
I learned several other things today - if the 5" Seeed LCD ever boots up black when the main 7" LCD boots up fine with desktop display, I can just go into terminal, then use xrandr to turn off the HDMI-2 port (5" on the HDMI1 connector), then set back up - it flashes, re-syncs and comes up online.
I use the following commands to bring a black-booted 5" Seeed LCD screen to working again:
xrandr --output HDMI-2 --off
xrandr --output HDMI-2 --mode 720x1280 --rotate right --pos 600x0
I took a video of the flashing screen in ‘slow motion’ on iphone and will email to support. Normal video mode on iphone could not capture flashing issue. Hopefully Seeed can send me a new display as no matter what I use to drive the LCD (desktops, laptops, RPI4), it always flashes for like 15min then stops flashing…
Thanks,
Joe