
Chapter 11. CPU Introduction Page 11-7
11.7 EZ-USB FX2 Register Interface
The FX2 peripheral logic (USB, GPIF, FIFOs, etc.) is controlled via a set of memory mapped regis-
ters and buffers at addresses 0xE400 through 0xFFFF. These registers and buffers are grouped as
follows:
• GPIF Waveform Descriptor Tables
• General configuration
• Endpoint configuration
• Interrupts
• Input/Output
•USB Control
• Endpoint operation
• GPIF/FIFOs
• Endpoint buffers
These registers and their functions are described throughout this manual. A full description of
every FX2 register appears in Chapter 15, "Registers"
11.8 EZ-USB FX2 Internal RAM
Figure 11-1. FX2 Internal Data RAM
Like the standard 8051, the FX2 contains 128 bytes of Internal Data RAM at addresses 0x00-0x7F
and a partially populated SFR space at addresses 0x80-0xFF. An additional 128 indirectly-
addressed bytes of Internal Data RAM (sometimes called “IDATA”) are also available at addresses
0x80-0xFF.
Lower 128
Direct Addr
SFR Space
Direct Addr
Upper 128
Indirect Addr
0x00
0x7F
0x80
0xFF
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