NS7520B-1-I46 Digi International, NS7520B-1-I46 Datasheet - Page 323

• Manufacturer Part Number: NS7520B-1-I46
• Description: IC ARM MICROPROCESSOR 177BGA
• Manufacturer: Digi International
• Series: NET+ARM®r

Specifications of NS7520B-1-I46

• Applications: Network Processor
• Core Processor: ARM7
• Program Memory Type: External Program Memory
• Controller Series: -
• Ram Size: External
• Interface: EBI/EMI, Ethernet, DMA, SPI, UART
• Number Of I /o: 16
• Voltage - Supply: 1.4 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 177-LFBGA
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

N S 7 5 2 0 E r r a t a
The first byte of the Ethernet destination address is the first byte of the
organizationally unique identifier (OID) portion of the address. Mismatches that
occur only in this byte of the Ethernet destination address are rare.
Workaround
In most cases, upper level protocols such as TCP/IP check the software level address
of the packets and reject any packets not sent to the proper address. Otherwise,
software must provide a check of this byte of the address.
Corrupt Ethernet receive packets
Under extremely rare conditions, packets passed between the Ethernet MAC and the
receive FIFO have a packet word transferred twice. The last word of the packet is
then dropped. For those Ethernet packets where the higher level protocol does not
provide a checksum, corrupted data might be passed to the application.
The problem frequency has been measured at Digi. Tests have shown frequency at
one in 20 million for large packets (1518 bytes) and approximately one in 10-500
million for small packets (64 bytes).
Workaround
Using standard protocols such as TCP/IP or UDP with checksum selected, bad packets
are discarded by the stack. Retransmission is requested, as appropriate, for the bad
packets. Note, however, that implementing the checksum results in latency and
performance degradation.
For protocols that do not have built-in error checking, the Ethernet driver provides a
software workaround. You can enable an
statement to perform a software
#ifdef
checksum. Go to the support website page and look for the application note called
Porting Ethernet Software CRC to NET+OS 5.0, 5.1, and 6.0.
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