Raspberry Pi Display Issues
Changing display settings
Editing display settings involve editing
/boot/config.txt file but on recent version of NanoDLP it become much easier as you can do it by going to:
System menu > Tools page > Edit Raspberry Pi Settings
For more information on available display settings on config.txt visit Raspberry Pi config.txt video section.
Display is rotated / flipped
Add one of lines below based on the issue, then reboot
# Normal display_rotate=0 # 90 degrees display_rotate=1 # 180 degrees display_rotate=2 # 270 degrees display_rotate=3 # horizontal flip display_rotate=0x10000 # vertical flip display_rotate=0x20000
Missing or extra gap over border
Blank area over display border or part of image is missing.
You probably could fix it by playing with overscan settings.
disable_overscan=1 overscan_left=0 overscan_right=0 overscan_top=0 overscan_bottom=0
Only one third of display being used or one third is visible
Probably display is monochrome but you setup it on NanoDLP as RGB display or reverse.
Display is blank or wrong picture
It means your display driver specifications are not detected correctly with Raspberry Pi EDID.
It is bit challenge to come up with correct values without display driver manufacturer help. Try correct HDMI related options on config.txt. Sometimes Pi4 and Pi3 configs could differ which makes things more difficult.