Non-PCI Single-Chip Full Duplex Ethernet Controller with Magic Packet
6. En-queue packet into TX FIFO
7. En-queue rest of packets, if any, into TX FIFO (restore TX FIFO)
ERCV INT - Early receive interrupt. Set whenever a receive packet is being received, and the number of bytes
received into memory exceeds the value programmed as ERCV THRESHOLD (Bank 3, Offset Ch). ERCV INT
stays set until acknowledged by writing the INTERRUPT ACKNOWLEDGE REGISTER with the ERCV INT bit
set.
EPH INT - Set when the Ethernet Protocol Handler section indicates one out of various possible special
conditions. This bit merges exception type of interrupt sources, whose service time is not critical to the
execution speed of the low level drivers. The exact nature of the interrupt can be obtained from the EPH Status
Register (EPHSR), and enabling of these sources can be done via the Control Register. The possible sources
are:
1. LINK - Link Test transition
2. CTR_ROL - Statistics counter roll over
3. TXENA cleared - A fatal transmit error occurred forcing TXENA to be cleared. TX_SUC will be low
and the specific reason will be reflected by the bits:
3.1
3.2
3.3
3.4
3.5
TXUNRN - Transmit under-run
SQET - SQE Error
LOST CARR - Lost Carrier
LATCOL - Late Collision
16COL - 16 collisions
Any of the above interrupt sources can be masked by the appropriate ENABLE bits in the Control Register.
1) LE ENABLE (Link Error Enable), 2) CR ENABLE (Counter Roll Over), 3) TE ENABLE (Transmit Error
Enable)
EPH INT will only be cleared by the following methods:
1. Clearing the LE ENABLE bit in the Control Register if an EPH interrupt is caused by a LINK_OK
transition.
2. Reading the Counter Register if an EPH interrupt is caused by statistics counter roll over.
3. Setting TXENA bit high if an EPH interrupt is caused by any of the fatal transmit error listed above (3.1
to 3.5).
RX_OVRN INT - Set when 1) the receiver aborts due to an overrun due to a failed memory allocation, 2)
the receiver aborts due to a packet length of greater than 2K bytes, or 3) the receiver aborts due to the
RCV DISCRD bit in the ERCV register set. The RX_OVRN INT bit latches the condition for the purpose of
being polled or generating an interrupt, and will only be cleared by writing the acknowledge register with
the RX_OVRN INT bit set.
ALLOC INT - Set when an MMU request for TX ram pages is successful. This bit is the complement of the
FAILED bit in the ALLOCATION RESULT register. The ALLOC INT bit is cleared by the MMU when the
next allocation request is processed or allocation fails.
TX EMPTY INT - Set if the TX FIFO goes empty, can be used to generate a single interrupt at the end of a
sequence of packets enqueued for transmission. This bit latches the empty condition, and the bit will stay
set until it is specifically cleared by writing the acknowledge register with the TX EMPTY INT bit set. If a
real time reading of the FIFO empty is desired, the bit should be first cleared and then read.
The TX_EMPTY MASK bit should only be set after the following steps:
a) A packet is enqueued for transmission
SMSC LAN91C965v&3v
Page 59
Rev. 09/10/2004
DATASHEET
SMSC [ SMSC CORPORATION ]
