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4.0 Register Set (Continued)

25-24

PS_STHI

RX Stat FIFO Hi Threshold

Status FIFO Threshold for initiating a pause frame with a length field of 0.

This allows termination of an active pause interval when the status FIFO

has enough space available. The following encoding determines when a

length 0 pause frame will be sent:

00: Disabled

01: 2 or more packets available

10: 4 or more packets available

11: 8 or more packets available

This value, if enabled, should always be equal to or greater than the low

threshold (PS_STLO). When disabling the high threshold, the PS_FFHI

field should also be set to disabled.

23-22

PS_STLO

RX Stat FIFO Lo Threshold

Status FIFO Threshold for initiating a pause frame. Upon reception of a

valid packet, a pause frame will be transmitted if space remaining in the

status FIFO is less than the threshold value. The encoding is as follows:

00: Disabled

01: Less than 2 packets available

10: Less than 4 packets available

11: Less than 8 packets available

21-20

PS_FFHI

RX Data FIFO Hi Threshold

Data FIFO Threshold for initiating a pause frame with a length field of 0.

This allows termination of an active pause interval when the data FIFO has

enough space available. The following encoding determines when a length

0 pause frame will be sent:

00: Disabled

01: 2K or more bytes available

10: 4K or more bytes available

11: 8K or more bytes available

This value, if enabled, should always be equal to or greater than the low

threshold (PS_FFLO). When disabling the high threshold, the PS_STHI

field should also be set to disabled.

19-18

PS_FFLO

RX Data FIFO Lo Threshold

Data FIFO Threshold for initiating a pause frame. Upon reception of a valid

packet, a pause frame will be transmitted if space remaining in the data

FIFO is less than the threshold value. The encoding is as follows:

00: Disabled

01: Less than 2K bytes available

10: Less than 4K bytes available

11: Less than 8K bytes available

PS_TX

Transmit Pause Frame

This is a manual method of sending a pause frame. This bit will remain set

until the pause frame is transmitted. R/W

Reserved

Reserved. R/W

15-0

PAUSE_CNT Pause Counter Value

Pause Length field which will be sent in a Transmit Pause frame. R/W

DP83821 Datasheet(PDF) 57 Page - National Semiconductor (TI)

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