MB86960 Datasheet, PDF (28/65 Pages) Fujitsu Component Limited. – NETWORK INTERFACE CONTROLLER with ENCODER/DECODER (NICE)

MB86960
Two of the control bits allow reception of packets with
certain types of errors. The ACPT BAD PKTS bit, when
set, causes the receiver to retain and store in the buffer
packets with CRC, alignment and/or short length errors
provided there was no indication of collision during
reception. Likewise, the ACPT SHORT PKTS bit, when
set, allows the retention of short packets down to and
including only six bytes in length, excluding preamble
and CRC, provided there was no indication of collision
during reception and no alignment or CRC error. Under
normal operation, packets with less than 60 bytes, the
IEEE 802.3 lower limit, would be discarded. These
functions are provided for diagnostic purposes. Packets
are accepted only if both the address filter and the error
filter are passed. Packets with no content errors, i.e., short,
alignment or CRC, are accepted without regard to
collision indicators.
Table 11. DLCR5 — Receive Mode Register
BIT SYMBOL TYPE
DESCRIPTION
7
0
N RESERVED: Write 0.
0
6
RX BUF
R RECEIVE BUFFER EMPTY: Status bit which indicates that the receive buffer does not have
EMTY
1 any complete packets to read. (Read only).
5
ACPT
R ACCEPT PACKETS WITH ERRORS: When set high, allows packets with CRC, alignment
BAD
W and/or short length errors to be saved into the receive buffer for analysis, provided there was
PKTS
0 no indication of collision during reception. Otherwise such packets would be discarded
automatically by the receiver and removed from the buffer. See also Table 8.
4
40 BIT
R 40 BIT ADDRESS: When set high, instead of the customary 48-bit NODE ID address filter,
ADDR
W only the first 40 bits of the NODE ID are compared (NODE ID 0–4).
0
3
ACPT
R ACCEPT SHORT PACKETS: When set high, allows short packets (packets with less than
SHORT
W 60 bytes, excluding Preamble and CRC, i.e. below IEEE minimum length) down to 6 bytes,
PKTS
0 excluding preamble and CRC, to be saved into the receive buffer, provided there was no CRC
or alignment error and no indication of collision during reception. Otherwise such packets
would be discarded automatically by the receiver and removed from the buffer. See also Table
8.
2
1
N RESERVED: Write 1.
0
1
AF1
R ADDRESS FILTER MODE: AF1 and AF0, DLCR5<1:0>, control the address filtering on
W incoming packets. See table below under AF0.
0
0
AF0
R ADDRESS FILTER MODE: AF1 and AF0, DLCR5<1:0>, control the address filtering on
W incoming packets:
1
AF1 AF0 Description of Address Accepted
0
1 NODE ID, Broadcast, Multicast & 2nd-24th bits of NODE ID
1
0 NODE ID, Broadcast, Multicast & Hash Table
0
0 Reject all packets
1
1 Accept all packet
Note: Self reception of broadcast and multicast packets prohibited except in “Accept all
packets” mode. When LBC is low (loopback mode) broadcast packets can be
self-received, except in “Reject all packets” mode.