Inside EZ-USB
Outside EZ-USB
FFFF
External
Data
Memory
(RD,WR)
External
Code
Memory
(PSEN)
8000
7B40
Registers(RD,WR)
(Note 1)
External
Data
Memory
(RD, WR)
2000
1FFF
1F3F
Unused Bulk Buffers
(RD,WR)
(Note 1)
1B40
Data (RD,WR)
0000
Note 1: OK to populate data memory here--RD#, WR#, CS# and OE# are inactive.
Figure 3-5. EZ-USB Memory Map with EA=1
When EA=1 (Figure 3-5), all code (PSEN) memory is external. All internal EZ-USB
RAM is data memory. This gives the user over 6-KB of general-purpose RAM, accessible
by the MOVX instruction.
Note
Figures 3-4 and 3-5 assume that the EZ-USB chip uses isochronous endpoints, and there-
fore that the ISODISAB bit (ISOCTL.0) is LO. If ISODISAB=1, additional data RAM
appears internally at 0x2000-0x27FF, and the RD#, WR#, CS#, and OE# signals are
modified to exclude this memory space from external data memory.
Page 3-6
Chapter 3. EZ-USB Memory
EZ-USB TRM v1.9
CYPRESS [ CYPRESS ]
