Datasheet

 2016-2017 Microchip Technology Inc. DS00002117F-page 43
KSZ9031RNX
4.3 MMD Registers
MMD registers provide indirect read/write access to up to 32 MMD device addresses with each device supporting up to
65,536 16-bit registers, as defined in Clause 22 of the IEEE 802.3 Specification. The KSZ9031RNX, however, uses only
a small fraction of the available registers. See the Register Map section for a list of supported MMD device addresses
and their associated register addresses.
The following two standard registers serve as the portal registers to access the indirect MMD registers.
• Standard register Dh – MMD Access – Control
• Standard register Eh – MMD Access – Register/Data
Note 4-1 RW = Read/Write.
Examples:
MMD Register Write
Write MMD - Device Address 2h, Register 10h = 0001h to enable link-up detection to trigger PME for WOL.
1. Write Register Dh with 0002h // Set up register address for MMD – Device Address 2h.
2. Write Register Eh with 0010h // Select Register 10h of MMD – Device Address 2h.
3. Write Register Dh with 4002h // Select register data for MMD – Device Address 2h, Register 10h.
4. Write Register Eh with 0001h // Write value 0001h to MMD – Device Address 2h, Register 10h.
MMD Register Read
Read MMD - Device Address 2h, Register 11h – 13h for the magic packet’s MAC address.
1. Write Register Dh with 0002h // Set up register address for MMD – Device Address 2h.
2. Write Register Eh with 0011h // Select Register 11h of MMD – Device Address 2h.
3. Write Register Dh with 8002h // Select register data for MMD – Device Address 2h, Register 11h.
4. Read Register Eh // Read data in MMD – Device Address 2h, Register 11h.
5. Read Register Eh // Read data in MMD – Device Address 2h, Register 12h.
6. Read Register Eh // Read data in MMD – Device Address 2h, Register 13h.
TABLE 4-5: MMD PORTAL REGISTERS
Address Name Description
Mode
Note 4-1
Default
Register Dh - MMD Access – Control
D.15:14 MMD -
Operation
Mode
For the selected MMD device address (Bits [4:0] of
this register), these two bits select one of the fol-
lowing register or data operations and the usage
for MMD Access – Register/Data (Reg. Eh).
00 = Register
01 = Data, no post increment
10 = Data, post increment on reads and writes
11 = Data, post increment on writes only
RW 00
D.13:5 Reserved Reserved RW 00_0000_000
D.4:0 MMD –
Device
Address
These five bits set the MMD device address RW 0_0000
Register Eh - MMD Access – Register/Data
E.15:0 MMD –
Register/
Data
For the selected MMD device address (Reg. Dh,
Bits [4:0]),
When Reg. Dh, Bits [15:14] = 00, this register
contains the read/write register address for the
MMD device address.
Otherwise, this register contains the read/write
data value for the MMD device address and its
selected register address.
See also Register Dh, Bits [15:14] descriptions for
post increment reads and writes of this register for
data operation.
RW 0000_0000_
0000_0000