LAN91C94 datasheet(38/120 Pages) SMSC

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OFFSET

NAME

EPH STATUS REGISTER

TYPE

READ ONLY

SYMBOL

EPHSR

This register stores the status of the last transmitted frame. This register value, upon individual

transmit packet completion, is stored as the first word in the memory area allocated to the packet.

Packet interrupt processing should use the copy in memory as the register itself will be updated by

subsequent packet transmissions. The register can be used for real time values (like TXENA and

LINK OK). If TXENA is cleared the register holds the last packet completion status.

HIGH

BYTE

TXUNRN

LINK_OK

RX_OVRN

CTR_ROL

EXC_DEF

LOST

CAR

LATCOL

LOW

BYTE

TX DEFR

LTX BRD

SQET

16COL

LTX MULT

MULCOL

SNGLCOL

TX_SUC

TXUNRN - Transmit Underrun. Set if underrun

occurs, it also clears TXENA bit in TCR. Cleared

by setting TXENA high. This bit should never be

set under normal operation.

LINK_OK - State of the 10BASE-T Link Integrity

Test. A transition on the value of this bit

generates an interrupt when the LE ENABLE bit

in the Control Register is set.

RX_OVRN - Upon receive overrun, the receiver

temporarily asserts this bit. The receiver stays

enabled and subsequent frames will be received

normally if memory becomes available.

The

RX_OVRN INT bit in the Interrupt Status

cleared by the CPU. Note that receive overruns

could occur only if receive memory allocations

fail.

CTR_ROL - Counter Roll over. When set one or

more 4 bit counters have reached maximum

count (15). Cleared by reading the ECR register.

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

LAN91C94 Datasheet(PDF) 38 Page - SMSC Corporation

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