Datasheet

ENC424J600/624J600
DS39935C-page 122  2010 Microchip Technology Inc.
13.1.8 TRANSMIT ABORT
The transmit abort interrupt occurs when the transmis-
sion of a frame has been aborted. An abort can occur
for any of the following reasons:
• Excessive collisions occurred as defined by the
Retransmission Maximum, MAXRET<3:0> bits
(MACLCON<3:0>), setting. If this occurs, the
COLCNT bits (ETXSTAT<3:0>) will indicate the
number of collisions that occurred.
• A late collision occurred after 63 bytes were trans-
mitted. If this occurs, LATECOL (ETXSTAT<10>)
will be set.
• The medium was busy and the packet was
deferred. If this occurs, EXDEFER (ETXSTAT<8>)
will be set.
• The application aborted the transmission by
clearing TXRTS (ECON1<1>).
The interrupt should be cleared by software once it has
been serviced.
To enable the transmit abort interrupt, set TXABTIE
(EIE<2>).
13.1.9 RECEIVE ABORT
The receive abort interrupt occurs when the reception
of a frame has been aborted. A frame being received is
aborted when the Head Pointer attempts to overrun the
Tail Pointer, or when the packet counter has reached
FFh. In either case, the receive buffer is full and cannot
fit the incoming frame, so the packet has been
dropped. This interrupt does not occur when packets
are dropped due to the receive filters rejecting a
packet. The interrupt should be cleared by software
once it has been serviced.
To enable the receive abort interrupt, set RXABTIE
(EIE<1>). The corresponding interrupt flag is RXABTIF
(EIR<1>).
13.1.10 RECEIVE PACKET COUNTER FULL
The receive packet counter full interrupt occurs when
the PKTCNT (ESTAT<7:0>) bits have reached FFh.
This indicates that the counter for received frames is
full and no more packets can be received. If a packet
arrives after this flag is set, it will cause the receive
abort interrupt flag to be set. This flag is cleared by
hardware once the PKTCNT bits are decremented.
To enable the receive packet counter full interrupt, set
PCFULIE (EIE<0>).
13.2 Wake-on-LAN/Remote Wake-up
Wake-on-LAN or remote wake-up is useful for conserv-
ing system power. The host controller and other
subsystems can be placed in Low-Power mode, then
configured to wake-up when a Magic Packet™ is
received by the ENC424J600/624J600 devices.
For Wake-on-LAN to operate correctly, the device must
not be in Low-Power mode and the receive module
must be enabled. When a Magic Packet arrives, the
device wakes the host controller via the INT
signal.
To configure the device for Wake-on-LAN:
1. Set the host controller to wake-up on an external
interrupt signal from INT
.
2. Set CRCEN (ERXFCON<6>), RUNTEN
(ERXFCON<4>) and MPEN (ERXFCON<14>).
Clear all other filter enable bits. This configures
the device to only accept Magic Packets.
3. Service all pending packets.
4. Set PKTIE (EIE<6>) and INTIE (EIE<15>) to
interrupt when a packet is accepted.
5. Put the host controller and other subsystems to
Sleep to save power.
Once a Magic Packet is received, PKTCNT is incre-
mented to ‘
1’, causing the device to assert the interrupt
signal. When the host wakes up, it needs to restore the
normal filter configuration and continue performing its
tasks.
For more details about the Magic Packet filter, refer to
Section 10.10 “Magic Packet™ Collection Filter”.