Question: In Keil Uvision project memory settings, I can set up the RAM ranging from 0x0000 to 0x1FFF, but I cannot set up RAM from 0xE000 to 0xFFFF. The error message says "Xdata memory range out of bounds".
Answer: Figure 5-3 of the EZ-USB Technical Reference Manual shows what type of memory is available for off-chip use. The area 0xE000-0xFFFF is unavailable for WR/RD (xdata) accesses. It is available for PSEN code accesses, so if you use an external ROM in this address space you can try linking your code to use the space 0xE000-0xFFFF, operate the code from the ROM, and keep your xdata space below this area for RAM access.
