Gameboy Development Forum

I'm trying to make a scrolling bigger than 32x32. I get that I have to write the VRam just outside the viewable area, so Im working on that now, with this. I know those are all IN the viewable area, and will have to move every time the key is pressed, but one thing at a time.

When I do this, it just pastes some empty tiles around the left and right, and identical characters on the top and bottom (blank tiles with a few others in teh same position regardless of what point in the array I point to.) I'm almost past this step, and I've tried this for like 10 hours over the past week, but I need some help because the set_bkg_tiles function does NOT want to cooperate. I know I can use int varuables in there because my collision detection function looks like this...

locInMap=(((heroY-1)*50)+heroX);
if (Testmap[locInMap]<10)

I'm just putting the impassable tiles above a certain value, but locInMap is an int, so thats not the problem. (and the map is 50x50. I'll replace it with a variable eventually, but let's get this working first. Does anyone have any advice for me?

if ( keys&J_A ) {set_bkg_tiles(0,0,32,1,Testmap[0]);
    set_bkg_tiles(0,17,32,1,Testmap[535]);
    for(n = 0; n!= 32; n++) {
        set_bkg_tiles(0,n,1,n+1,Testmap[b]);
        set_bkg_tiles(19,n,1,n+1,Testmap[b]);
        b = b + 50;
        }
}