LAN91C100FD_06 datasheet(21/67 Pages) SMSC

21 / 67 page

SMSC DS – LAN91C100FD REV. B

Page 21

Rev. 01-20-06

EXC_DEF - Excessive Deferral. When set last/ current transmit was deferred for more than 1518 * 2 byte times. Cleared at

the end of every packet sent.

LOST_CARR - Lost Carrier Sense. When set indicates that Carrier Sense was not present at end of preamble. Valid only if

MON_CSN is enabled. This condition causes TXENA bit in TCR to be reset. Cleared by setting TXENA bit in TCR.

LATCOL - Late collision detected on last transmit frame. If set a late collision was detected (later than 64 byte times into the

frame). When detected the transmitter jams and turns itself off clearing the TXENA bit in TCR. Cleared by setting TXENA in

TCR.

TX_DEFR - Transmit Deferred. When set, carrier was detected during the first 6.4

μs of the inter frame gap. Cleared at the

end of every packet sent.

LTX_BRD - Last transmit frame was a broadcast. Set if frame was broadcast. Cleared at the start of every transmit frame.

SQET - Signal Quality Error Test. In MII, SQET bit is always set after first transmit, except if SWFDUP=1. As a

consequence, the STP_SQET bit in the TCR register cannot be set as it will always result in transmit fatal error. In non-MII

systems, the transmitter opens a 1.6

μs window 0.8 μs after transmission is completed and the receiver returns inactive.

During this window, the transmitter expects to see the SQET signal from the transceiver. The absence of this signal is a

'Signal Quality Error' and is reported in this status bit. Transmission stops and EPH INT is set if STP_SQET is in the TCR is

also set when SQET is set. This bit is cleared by setting TXENA high.

16COL

- 16 collisions reached. Set when 16 collisions are detected for a transmit frame. TXENA bit in TCR is reset.

Cleared when TXENA is set high.

LTX_MULT - Last transmit frame was a multicast. Set if frame was a multicast. Cleared at the start of every transmit

frame.

MULCOL - Multiple collision detected for the last transmit frame. Set when more than one collision was experienced.

Cleared when TX_SUC is high at the end of the packet being sent.

SNGLCOL - Single collision detected for the last transmit frame. Set when a collision is detected. Cleared when TX_SUC is

high at the end of the packet being sent.

TX_SUC

- Last transmit was successful. Set if transmit completes without a fatal error. This bit is cleared by the start of a

new frame transmission or when TXENA is set high. Fatal errors are:

16 collisions (1/2 duplex mode only)

SQET fail and STP_SQET = 1 (1/2 duplex mode only)

FIFO Underrun

Carrier lost and MON_CSN = 1 (1/2 duplex mode only)

Late collision (1/2 duplex mode only)

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