AM79C985 Advanced Micro Devices, AM79C985 Datasheet - Page 21

• Manufacturer Part Number: AM79C985
• Description: enhanced Integrated Multiport Repeater Plus (eIMR+)
• Manufacturer: Advanced Micro Devices

Management Functions
The eIMR+ device receives management commands
in the form of byte-length data on the serial input pin,
SI. If the eIMR+ device is expected to provide data in
response to the command, it will send byte-length data
to the serial-output pin, SO. Both the input and output
data streams are clocked with the rising edge of the
SCLK signal. The byte-length data is in RS232 serial-
data format; that is, one start bit followed by eight data
bits. The externally generated clock at the SCLK pin
V
DD
1k
SELI_0
SELI_1
SELI_0
SELI_1
SELI_0
SELI_1
SELI_0
SELI_1
SELO
SELO
SELO
SELO
Figure 5. Internal Arbitration—eIMR+ Devices in Cascade
P R E L I M I N A R Y
Am79C985
SELI_0
SELI_1
SELI_0
SELI_1
may be either a free-running clock synchronized to the
input bit patterns, or a series of individual transitions
meeting the setup-and-hold times with respect to the
input bit pattern. If the latter method is used, 20 SCLK
clock transitions are required for management com-
mands that produce SO data, and 14 SCLK clock tran-
sitions are required for management commands that
do not produce SO data.
SELO
SELO
SELI_0
SELI_1
SELO
20651B-10
21