Outside EZ-USB
Inside EZ-USB
FFFF
External
Code
External
Data
Memory
(PSEN)
Memory
(RD,WR)
8000
7FFF
7B40
Registers(RD,WR)
(Note 1)
External
Data
Memory
(RD, WR)
Internal Code
Memory(PSEN)
(Note 2)
1000
0FFF
Data (RD,WR)
(Note 1)
0000
Note 1: OK to populate data memory here, but no RD# or WR# strobes are generated.
Note 2: OK to populate code memory here, but no PSEN# strobe is generated.
Figure 3-7. 32-KB ROM, 4-KB RAM Version
The EZ-USB 32-KB ROM version contains program memory from 0x0000 through
0x7FFF, and data memory from 0x0000 through 0x0FFF.
Code for this ROM version can be developed and tested using the AN2131Q with an
external code memory (EA=1, Figure 3-5). As long as the 8051 limits internal RAM
access to 0x0000-0x0FFF and accesses the EZ-USB registers and bulk data at 0x7B40-
0x7FFF, the code in the external memory will be the identical image of the code that will
ultimately be internal at 0x0000-0x7FFF in the ROM version.
Page 3-8
Chapter 3. EZ-USB Memory
EZ-USB TRM v1.9
CYPRESS [ CYPRESS ]
