AX88850

PRELIMINARY

ASIX ELECTRONICS CORPORATION

20

Collision State

The Collision State happens when these conditions exists:

a.

There are two or more signals high among M0_CRS[7:0],M1_CRS[7:0],CRS[1:0]. Or receive

collision messages from /IR_ACTO[7:0] in MII mode.

b.

At least two ports of PCS ports receive /J/K/ code group or receive collision message from

/IR_ACTO[7:0] in PCS mode.

c.

Only one carrier exists but RXDV still low exceeds 5 clock cycles. The repeater sends collision

pattern to all ports, that is, M0_TXEN[7:0] and M1_TXEN[7:0] all become high during collision

state.

3.4 Jabber State Machine

To prevent an illegally long reception of data from reaching the repeater unit, each port has its own jabber timer. If a

reception exceeds this duration(64K bit times for AX88850), the jabber condition will be detected. In this condition,

repeater unit will disable receive and transmit packets for the jabbered port and the other ports remain the normal

operation.

When the carrier is no longer detected for the jabbered port or reset the repeater, the jabber function will be clear and

re-enable reception and transmission.

3.5 Partition State Machine

The partition state machine is used to protect network from be upset by a port suffering continuous collision, each port

uses a partition state machine to detect and prevent this condition. When a port is suffering from continuous 32 or

64 times of collisions by CCLimits. Then it goes to Partition State. The port entering Partition State will be released

until a packet without collision more than 512 bit times or after power-on reset.

Partition function is enabled by default, and CCLimits is 64 by default. Enable/Disable partition function

(DIS_PART) and option of CCLimits to be 64 or 32 (COL_LIMIT32) are selected by station management access

logic.