The OBJDIR= directive is optional.

      Use it if you want to place your objects in a different directory
      from where you run the make script.

          Note! When you use the OBJDIR= directive, your objects
          will not be built in the current directory. This means that
          your linker script will also need to refer to the actual
          location of the objects.

     You may also override the OBJDIR=, which is active across all
     sections with individual directives for each section.

     So, you can do this:

     OBJDIR=OBJ\

     OBJDIR2=\OTHER\OBJ