AM79C985KCW AMD [Advanced Micro Devices], AM79C985KCW Datasheet - Page 22

• Manufacturer Part Number: AM79C985KCW
• Manufacturer: AMD [Advanced Micro Devices]

eIMR+/HIMIB Interconnection
The eIMR+ device interfaces directly to the HIMIB de-
vice for full repeater manageability. To this end, the
eIMR+ device has a management port and a serial out-
put that allows the HIMIB device to monitor port activity.
The eIMR+ device is designed to allow one or two
eIMR+ devices to operate with a single HIMIB device.
Because the HIMIB device can monitor nine ports (8 TP
ports & 1 AUI port), one of the eIMR+ AUI ports is not
managed (statistics not kept). When two eIMR+ devices
are connected to a HIMIB device, one is designated the
primary device and the other is designated the second-
ary device. This designation serves to identify which
device has the managed AUI port. The primary device
has the managed AUI port and TP4-7. The secondary
device has the unmanaged AUI port and TP0-3. Figure
6 shows how the HIMIB and eIMR+ devices are inter-
connected.
22
HIMIB
DV SS
SCLK
HIMIB
CRS
CRS_I
SI_D
AUI
SO
SI
M
SCLK
CRS
Figure 6. eIMR-to-HIMIB Connection
(Primary)
Port & TP[7:4]
SO
eIMR+
SI
SCLK SI
b) Two eIMR Devices Connected to a HIMIB
P R E L I M I N A R Y
V DD
a) One eIMR Device Connected to a HIMIB
CRS
SO
Am79C985
CRS_I
SI_D
AUI
M
Port & TP[3:0]
eIMR+
When only one eIMR+ device is connected to a HIMIB
device, the AUI port is managed. The HIMIB device
treats the twisted-pair ports as TP0-3.
Although the HIMIB device does not monitor the AUI
port on the secondary eIMR+ device, the AUI port on
the secondary device defaults to enabled at reset. The
port can be disabled via the Secondary AUI Port Enable
command.
Management Port Interface
The eIMR+ management port is made up of six signals:
SI, SI_D, SO, CRS, CRS_I, and SCLK. SI is the serial
input from an external management module or the
HIMIB device. On the secondary eIMR+ device, SI_D
is the response input from the primary eIMR+ device. It
is also used at reset to set the eIMR+ device as either
a primary or secondary device. CRS transmits the state
of the eIMR+ device’s internal carrier sense signals.
SCLK SI
CRS_I
SI_D
AUI
CRS
U
(Secondary)
SO
Port & TP[3:0]
eIMR+
SCLK SI
CRS
SO
20651B-11