In the setup and programming the prebuilt images are .bin files and instructions of building a bootable microSD card center around those bin files.  When I run bitbake I get .ubi and .ubifs files.  What are these files and how do they relate to the .bin files?  Is there a way to put these on a bootable microSD card?  Or is there a configuration setting somewhere in bitbake to make it produce .bin files instead of .ubi files?