EZ-USB Datasheet, PDF (57/334 Pages) Cypress Semiconductor – The EZ-USB USB Integrated Circuit

3.3 Expanding EZ-USB Memory
The 80-pin EZ-USB package provides a 16-bit address bus, an 8-bit bus, and memory
control signals PSEN#, RD#, and WR#. These signals are used to expand EZ-USB
memory.
Inside EZ-USB
FFFF
Outside EZ-USB
8000
7B40
Registers(RD,WR)
External
Data
Memory
(RD,WR)
(Note 1)
External
Code
Memory
(PSEN)
2000
1FFF
1F3F
1B40
0000
Unused Bulk Buffers
(RD,WR)
Code & Data
(PSEN,RD,WR)
External
Data
Memory
(RD, WR)
(Note 1)
(Note 2)
Note 1: OK to populate data memory here--RD#, WR#, CS# and OE# pins are inactive.
Note 2: OK to populate code memory here--no PSEN# strobe is generated.
Figure 3-4. EZ-USB Memory Map with EA=0
Figure 3-4 shows that when EA=0, the code/data memory is internal at 0x0000-0x1B40.
External code memory can be added from 0x0000-0xFFFF, but it appears in the memory
map only at 0x1B40-0xFFFF. Addressing external code memory at 0x0000-0x1B3F
when EA=0 causes the EZ-USB core to inhibit the #PSEN strobe. This allows program
memory to be added from 0x0000-0xFFFF without requiring decoding to disable it
between 0x0000 and 0x1B3F.
Page 3-4
Chapter 3. EZ-USB Memory
EZ-USB TRM v1.9