Preliminary - Information Subject to Change - 9/24/98
5 - 12
EZ-USB Development Board
Configuration 01
This configuration adds 32 Kilobytes of external RAM at 8000-
FFFF. This mode is useful for developing systems that require
external memory or memory-mapped peripherals. The debug
monitor is loaded into the top 32 Kilobytes of RAM, the user code
is loaded into the EZ-USB internal RAM, and the bottom 32
Kilobytes (minus the bottom 8K) is free for memory expansion
(See Note 1).
Configuration 11
The default memory configuration populates the full 8051 external
memory space with 64 Kilobytes of RAM. The 22V10 sets EA=0
so that internal EZ-USB 8K RAM occupies the address space 0000-
1FFF (See Note 1).
Configuration 10
This configuration is almost identical to configuration 11. The only
difference is that the 22V10 sets EA=1, forcing code fetches from
external RAM rather than from internal EZ-USB RAM. This
simulates ROM versions of the EZ-USB family, where the internal
8K RAM is data-only.
Note 1.
The EZ-USB RD# and WR# signals are inactive when
the EZ-USB 8051 accesses internal RAM. Therefore a
32 Kilobyte memory can be used at 0000-7FFF without
requiring external address decoding to de-select
accesses from 0000-1FFF.
Note 2.
EZ-USB bulk endpoint buffers reside at 7B40 and are
aliased at 1B40 to allow unused buffers to add to
available RAM. For details see the EZ-USB Technical
Reference Manual Chapter 3, “EZ-USB Memory”.
