AM79C874VC AMD (ADVANCED MICRO DEVICES), AM79C874VC Datasheet - Page 31

• Manufacturer Part Number: AM79C874VC
• Manufacturer: AMD (ADVANCED MICRO DEVICES)

Specifications of AM79C874VC

• Lead Free Status / RoHS Status: Not Compliant

Bad Management Frame Handling
The management block of the device can recognize
management frames without preambles (preamble
suppression). However, if it receives a bad manage-
ment frame, it will go into a Bad Management Frame
state. It will stay in this state and will not respond to any
management frame without preambles until a frame
with a full 32-bit preamble is received, then it will return
to normal operation.
A bad management frame is a frame that does not
comply with the IEEE standard specification. It can be
one with less than 32-bit preamble, with illegal OP field,
etc. However, a frame with more than 32 preamble bits
is considered to be a good frame.
After a reset, the NetPHY-1LP device requires a mini-
mum preamble of 32 bits before management data
(MDIO) can be received. After that, the management
data being received by the NetPHY-1LP device does
not require a preamble.
22235K
D A T A
S H E E T
Am79C874
REGISTER DESCRIPTIONS
The following table lists the supported registers (regis-
ter addresses are in decimal).
The Physical Address of the PHY is set using the pins
defined as PHYAD[4:0]. These input signals are
strapped externally and sampled as when reset goes
high. The PHYAD pins can be reprogrammed via soft-
ware.
Serial Management Registers
A detailed definition of each Serial Management regis-
ter is provided in the following table.
Register
Address
25-31
Type
8-15
RW
RO
SC
RC
LH
LL
16
17
18
19
20
21
22
23
24
0
1
2
3
4
5
6
7
Table 13. Serial Management Registers
Table 12. Supported Registers
Description
Readable and writable
Self Clearing
Latch Low until clear
Read Only
Cleared on the read operation
Latch high until clear
Description
MII Management Control Register
MII Management Status Register
PHY Identifier 1 Register
PHY Identifier 2 Register
Auto-Negotiation Advertisement Register
Auto-Negotiation Link Partner Ability Register
Auto-Negotiation Expansion Register
Next Page Advertisement Register
Reserved
Miscellaneous Features Register
Interrupt Control/Status Register
Diagnostic Register
Power Management & Loopback Register
Reserved
Mode Control Register
Reserved
Disconnect Counter
Receive Error Counter
Reserved
31