DP83850C datasheet(7/37 Pages) NSC

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2.0 Pin Descriptions (Continued)

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2.2 Inter Repeater and Management Bus Interface

Signal Name

Type

Active

Description

IRD[3:0]

I/O/Z, M

—

Inter Repeater Data: Nibble data input/output. Transfers data from the “active”

DP83850C to all other “inactive” DP83850Cs. The bus master of the IRD bus is de-

termined by IR_VECT bus arbitration.

Note: Input buffer has a weak pull-up.

/IRD_ER

I/O/Z, M

low

Inter Repeater Data Error: This signal carries the RX_ER state across the Inter Re-

peater bus. Used to track receive errors from the physical layer in real-time

/IRD_V

I/O/Z, M

low

Inter Repeater Data Valid: This signal carries the inverted RX_DV state across the

Inter Repeater bus. It is used to frame good packets.

Note: A recommended 1.5K pull-up prevents ﬁrst repeated packet corruption .

IRD_CK

I/O/Z, M

—

Inter Repeater Data Clock: All Inter Repeater signals are synchronized to the rising

edge of this clock.

Note: Input buffer has a weak pull-up.

IRD_ODIR

O, L

high

Inter Repeater Data Outward Direction: This pin indicates the direction of data for

an external transceiver. It is HIGH when IRD[3:0], /IRD_V, /IRD_CK, and /IRD_ER

are driven out towards the Inter Repeater bus, and LOW when data is being received

from the bus.

/IR_ACTIVE

I/O/OC, M

low

Inter Repeater Activity: This “open-collector” type output is asserted when the re-

peater senses network activity.

Note: Input buffer has a weak pull-up.

/IR_COL_IN

low

Inter Repeater Collision In: Indication from another DP83850C that it senses two or

more ports receiving or another DP83850C has detected a collision.

Note: Input buffer has a weak pull-up.

/IR_COL_OUT O/OC, M

low

Inter Repeater Collision Out: Asserted when the DP83850C senses two or more

ports receiving or non-idle, either 1) within this DP83850C or 2) in another

DP83850C, using the IR_VECT number to decide (the IR_VECT number read will dif-

fer from the number of this DP83850C if another device is active).

IR_VECT[4:0]

I/O/OC, M

high

Inter Repeater Vector: When the repeater senses at least one of its ports active, it

drives its unique vector (from RID[4:0]) onto these pins. If the vector value read back

differs from its own (because another vector is being asserted by another device),

then this DP83850C will:

1) not drive IRD_ODIR signal and,

2) the IRD[3:0], /IRD_ER, /IRD_V, and IRD_CK signals will be placed in TRI-STATE

mode.

However, if the value read back is the same as its own RID number, this DP83850C

will continue to drive the Inter Repeater bus signals. Note that these vectors are driv-

en onto the bus for the duration of /ACTIVEO assertion.

Note: Input buffer has a weak pull-up.

MD[3:0]

I/O/Z, M

high

Management Data: Outputs management information for the DP83856 manage-

ment chip. During packet reception the DP83850C drives its RID number and the port

number of the receiving port onto this bus.

Note: Input buffer has a weak pull-up.

/M_DV

I/O/Z, M

low

Management Data Valid: Asserted when valid data is present on MD[3:0].

Note: Input buffer has a weak pull-up.

M_CK

I/O/Z, M

—

Management Clock: All data transfers on the management bus are synchronize to

the rising edge of this clock.

Note: Input buffer has a weak pull-up.

/M_ER

I/O/Z, M

low

Management Error: Asserted when an Elasticity Buffer overrun or under-run error

has been detected.

Note: Input buffer has a weak pull-up.

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