Xilinx LOGICORE UG144 - Manual (Page 87)

1-Gigabit Ethernet MAC v8.5 User Guide www.xilinx.com 87
UG144 April 24, 2009
Using the Optional Management Interface R
-- DISCONTINUED PRODUCT --
There are two different transaction types of MDIO for write and read. They are described
in this section.
Abbreviations Used
The following abbreviations apply for the remainder of this chapter.
•
PRE Preamble
•
ST Start of frame
• OP Operation code
• PHYAD PHY address
• REGAD Register address
• TA Turnaround
Write Transaction
Figure 8-6 shows a write transaction across the MDIO, as defined by OP=’01.’ The
addressed MMD (PHYAD) device takes the 16-bit word in the data field and writes it to the
register at REGAD.
Figure 8-5: Typical MDIO-managed System
MAC 1 MAC 2
STA
mdc
mdio
MMD
MMD
MMD
MMD
MMD
MMD
Figure 8-6: MDIO Write Transaction
Z 1 1 1 0 0 1 P4 P3 P2 P1 P0 R4 R3 R2 R1 R0 1 0 D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
1 Z Z Z
mdc
mdio
IDLE IDLE 32 bits
PRE
ST OP PHYAD REGAD TA 16-bit WRITE DATA
STA drives MDIO