Weird striping in tile graphics on Nintendo DS

Answer 1

Two things. For one, the striping is most likely a VRAM conflict, although it's been a while since I did DS dev last. Double check where you're copying your graphics and your tile data. Mode 5 uses two text backgrounds, which should be behaving exactly the same if they're initialized a certain way, so I'm not sure what's going on there.

In any case, since you have two backgrounds working, why not just set their priorities in their registers to swap their z order? Background are only drawn in a particular order by default, you can set their priority to have the system draw them in any order you like.

Answer 2

a breif look at background.h makes it look like you are using BG1 and BG2. For mode 5, according to:

http://nocash.emubase.de/gbatek.htm

layer 0 and 1 are normal and 2 and 3 are extended. I dont know what extended means. If you want to just do normal tile stuff you probably want to bgInit 0 and 1 not 1 and 2.

You can change the priorities around at will, layer 0 is not necessarily on top of 1, etc. Look at the BGxCNT registers (BG0CNT, BG1CNT,...) and the priority bits. Now if the priority is a tie then yes the layer number determines who wins.