DP8390DN National Semiconductor, DP8390DN Datasheet - Page 32

• Manufacturer Part Number: DP8390DN
• Description: IC NIC (NETWORK INT CTRL)48-DIP
• Manufacturer: National Semiconductor

Specifications of DP8390DN

• Controller Type: Network Interface Controller (NIC)
• Voltage - Supply: 5V
• Current - Supply: 40mA
• Mounting Type: Through Hole
• Package / Case: 48-DIP (0.600", 15.24mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Operating Temperature: -
• Interface: -
• Other names: *DP8390DN

12 0 Loopback Diagnostics
Note 1 CDH is set CRS is not set since it is generated by the external
encoder decoder
Note 1 CDH and CRS should not be set The TSR however could also
contain 01H 03H 07H and a variety of other values depending on whether
collisions were encountered or the packet was deferred
Note 2 Will contain 08H if packet is not transmittable
Note 3 During external loopback the NIC is now exposed to network traffic
it is therefore possible for the contents of both the Receive portion of the
FIFO and the RSR to be corrupted by any other packet on the network Thus
in a live network the contents of the FIFO and RSR should not be depended
on The NIC will still abide by the standard CSMA CD protocol in external
loopback mode (i e The network will not be disturbed by the loopback
packet)
Note 4 All values are hex
CRC AND ADDRESS RECOGNITION
The next three tests exercise the address recognition logic
and CRC These tests should be performed using internal
loopback only so that the NIC is isolated from interference
from the network These tests also require the capability to
generate CRC in software
The address recognition logic cannot be directly tested The
CRC and FAE bits in the RSR are only set if the address of
the packet matches the address filters If errors are expect-
ed to be set and they are not set the packet has been
rejected on the basis of an address mismatch The following
sequence of packets will test the address recognition logic
The DCR should be set to 40H the TCR should be set to
03H with a software generated CRC
Note 1 Status will read 21H if multicast address used
Note 2 Status will read 22H if multicast address used
Note 3 In test A the RSR is set up In test B the address is found to match
since the CRC is flagged as bad Test C proves that the address recognition
logic can distinguish a bad address and does not notify the RSR of the bad
CRC The receiving CRC is proven to work in test A and test B
Note 4 All values are hex
NIC External
NIC External
Test A
Test B
Test C
Test
PATH
PATH
Packet Contents
Non-Matching
TCR
Matching
Matching
TCR
Address
06
04
RCR
RCR
00
00
03(1)
TSR
43(1)
TSR
Good
CRC
Bad
Bad
RSR
RSR
02
(Continued)
02
Results
01(1)
02(2)
RSR
01
02(2)
ISR
ISR
02
32
NETWORK MANAGEMENT FUNCTIONS
Network management capabilities are required for mainte-
nance and planning of a local area network The NIC sup-
ports the minimum requirement for network management in
hardware the remaining requirements can be met with soft-
ware counts There are three events that software alone
can not track during reception of packets CRC errors
Frame Alignment errors and missed packets
Since errored packets can be rejected the status associat-
ed with these packets is lost unless the CPU can access the
Receive Status Register before the next packet arrives In
situations where another packet arrives very quickly the
CPU may have no opportunity to do this The NIC counts
the number of packets with CRC errors and Frame Align-
ment errors 8-bit counters have been selected to reduce
overhead The counters will generate interrupts whenever
their MSBs are set so that a software routine can accumu-
late the network statistics and reset the counters before
overflow occurs The counters are sticky so that when they
reach a count of 192 (C0H) counting is halted An additional
counter is provided to count the number of packets NIC
misses due to buffer overflow or being offline
The structure of the counters is shown below
Additional information required for network management is
available in the Receive and Transmit Status Registers
Transmit status is available after each transmission for infor-
mation regarding events during transmission
Typically the following statistics might be gathered in soft-
ware
Traffic
Errors
CRC Errors
Alignment Errors
Excessive Collisions
Packet with Length Errors
Heartbeat Failure
Frames Sent OK
Frames Received OK
Multicast Frames Received
Packets Lost Due to Lack of Resources
Retries Packet
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