AX88871AP Bripeater

ASIX ELECTRONICS CORPORATION

18

The signals on the IR bus (such as IRD[3:0], IRD_V_N, IRD_ER_N, IRD_CK) flow either into or out of

the repeater depending upon the repeater‘s state. Only if the repeater receive packet from local port without

collision occurs, the IR signals flow out of repeater. Otherwise, these IR signals flow into repeater.

In cascade system, it must guarantee that only one repeater drives these signals to avoid contention.

3.7 RID Receive-Transmit Interface(Daisy Chain Logic)

In the cascade system, repeater ID of each chip will be re-arranged by serial in/serial out daisy chain

logic. The logic use DAISY_IN pin to monitor the RID value of the previous chained chip, and override the

original ID of the current chip with the value of (RID+1) . Use the DAISY_OUT pin to periodically (about

200us) send out the exact RID of the current chip to inform the next chained chip. By this way, each repeater

chip in 8 AX88871A stackable application will keep unique ID of itself. The RID is used in inter repeater bus

arbitration.

DAISY_IN/OUT frame format

idle

start bit

data0

data1

data2

data3

1

0

RID[0]

RID[1]

RID[2]

PARITY

Notes: PARITY = 1 when sum of 1‘s in RID[2:0] is even

If no daisy-chain input, that is, DAISY_IN keep high, the RID of current chip can be clear to 0 during

time out period. The timer for time out is about 4sec.

There are a input setting , /DIS_DAISY, which enable/disable daisy-chain function. With the low

setting , the RID of current chip don‘t care the present data on DAISY_IN and can‘t be overrided.

3.8 LED Display Interface

AX88871A provides per-port LED status indication for partition, jabber, activity and support rate -

based LED for global partition and collision, utilization (%) for 10/100Mbps. .Detail function is described on

the previous pin description(LED interface). LED[2:0] are all active low. There are two display ways :

complicated and simple way. It depends on the setting of MODE.

Multiple chips cascaded application (MODE = 1)

LED[2:0] Status Driver Wave-form as follows :

JAB7

JAB6

JAB5

JAB4

JAB3

JAB2

JAB1

JAB0

PART

7

PART

6

LED_CK

LED[0]

'0'

RID2

RID1

RID0

100M

GCOL

10M

GCOL

LED[1]

LED[2]

D0

D1

D2

D3

D4

D5

D6

D7

D8

D9

D11

D12

D13

D14

D10

D15

PART

0

PART

1

PART

2

PART

3

PART

4

PART

5

ACT0

ACT1

ACT2

ACT3

ACT4

ACT5

ACT6

ACT7

10M

UTI7

10M

UTI0

10M

UTI1

10M

UTI2

10M

UTI3

10M

UTI4

10M

UTI5

10M

UTI6

100M

UTI7

100M

UTI0

100M

UTI2

100M

UTI3

100M

UTI4

100M

UTI5

100M

UTI6

100M

UTI1

G

PART

RAM

FAIL