PIC18F97J60_11 Datasheet, PDF (222/492 Pages) Microchip Technology – 64/80/100-Pin, High-Performance, 1-Mbit Flash Microcontrollers with Ethernet

PIC18F97J60 FAMILY
19.2 Ethernet Buffer and Register
Spaces
The Ethernet module uses three independent memory
spaces for its operations:
• An Ethernet RAM buffer which stores packet data
as it is received and being prepared for
transmission.
• A set of 8-bit Special Function Registers (SFRs),
used to control the module, and pass data back and
forth between the module and microcontroller core.
• A separate set of 16-bit PHY registers used
specifically for PHY control and status reporting.
The Ethernet buffer and PHY Control registers are
contained entirely within the Ethernet module and can-
not be accessed directly by the microcontroller. Data is
transferred between the Ethernet and microcontroller
by using buffer and pointer registers mapped in the
microcontroller’s SFR space. The relationships
between the SFRs and the Ethernet module’s memory
spaces are shown in Figure 19-4.
FIGURE 19-4:
RELATIONSHIP BETWEEN MICROCONTROLLER AND ETHERNET
MEMORY SPACES
Microcontroller SFRs
EDATA
Ethernet Data
Ethernet Module
Ethernet Buffer
0000h
ERDPT(H:L)
EWRPT(H:L)
ETXST(H:L)
ETXND(H:L)
ERXST(H:L)
ERXND(H:L)
ERXRDPT(H:L)
ERXWRPT(H:L)
MIRD(H:L)
MIWR(H:L)
MIREGADR
Buffer Address
PHY Register Data (In/Out)
PHY Register Address
1FFFh
PHY Registers
00h
1Fh
Note:
Microcontroller SFRs are not shown in the order of their placement in the data memory space. Memory areas are
not shown to scale.
DS39762F-page 222
 2011 Microchip Technology Inc.