ENC624J600-I/PT Microchip Technology, ENC624J600-I/PT Datasheet - Page 102

• Manufacturer Part Number: ENC624J600-I/PT
• Description: IC ETHERNET CTRLR W/SPI 64-TQFP
• Manufacturer: Microchip Technology

Specifications of ENC624J600-I/PT

• Package / Case: 64-TFQFP
• Controller Type: Ethernet Controller
• Interface: SPI
• Voltage - Supply: 3 V ~ 3.6 V
• Current - Supply: 96mA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Input Voltage Range (max): 5.5 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Operating Supply Voltage: 3 V to 3.6 V
• Supply Current (max): 117 mA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: AC164132 - BOARD DAUGHTER PICTAIL ETHERNET
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

ENC424J600/624J600
10.7
The Multicast Collection filter checks the destination
address of incoming frames. If the Least Significant bit
(LSb) of the first byte of the destination address is set,
the frame will be accepted. This represents all Multicast
frames. If the frame has a Unicast destination, it will be
passed on to the next filter.
This filter is disabled at power-up. To enable this filter,
set MCEN (ERXFCON<1>). If the filter is disabled, all
frames will be passed on to the next lower priority filter,
regardless of destination address.
10.8
The Broadcast Collection filter checks the destination
address of incoming frames. If the destination address
is FF-FF-FF-FF-FF-FF, the frame will be accepted.
Frames matching this filter are designated as being
broadcast to all nodes that receive them. All frames
with other address values will be passed on to the next
filter.
This filter is enabled at power-up. To disable this filter,
clear BCEN (ERXFCON<0>). If the filter is disabled, all
frames will be passed on to the next lower priority filter,
regardless of destination address.
10.9
The Hash Table filter accepts frames based on their des-
tination address, and is configurable for up to 64 different
hash values. This filter allows the device to accept
frames for multiple destination addresses (without
accepting
Section 10.6 “Not-Me Unicast Collection Filter” ). It
can also be used to accept traffic for one or more
specific Multicast groups (without accepting all Multi-
cast traffic as described in Section 10.7 “Multicast
Collection Filter” ). Note that Hash Table collisions are
possible, so applications should still verify the MAC
address of accepted frames. This filter simply reduces
the amount of incoming traffic for these applications.
The filter performs a 32-bit CRC over the six destina-
tion address bytes in the packet, using the polynomial,
4C11DB7h. From the resulting 32-bit binary number, a
6-bit value is taken from bits<28:23>. This value, in
TABLE 10-1:
DS39935C-page 100
Register
EHT1
EHT2
EHT3
EHT4
Multicast Collection Filter
Broadcast Collection Filter
Hash Table Collection Filter
all
0F
1F
2F
3F
15
Not-Me
BIT ASSIGNMENTS IN HASH TABLE REGISTERS
0E
1E
2E
3E
14
traffic
0D
1D
2D
3D
13
as
0C
1C
2C
3C
12
described
0B
1B
2B
3B
11
0A
1A
2A
3A
10
Bit Numbers in Hash Table
in
09
19
29
39
9
08
18
28
38
8
turn, points to a location in a table formed by the Ether-
net Hash Table registers, ETH1 through ETH4. If the bit
in that location is set, the packet meets the Hash Table
filter criteria and is accepted. The specific pointer
values for each bit location in the table are shown in
Table 10-1.
An example of the Hash Table operation is shown in
Example 10-1. In this case, the destination address,
01-00-00-00-01-2C, produces a Hash Table Pointer
value of 34h, which points to bit 4 of ETH4. If this bit is
‘ 1 ’, the packet will be accepted. If this Hash Table bit is
‘ 0 ’, the packet will be passed to the next lower priority
filter.
By extension, if every bit in the Hash Table is set, the
filter criteria will always be met, so all packets will be
accepted if no higher priority filter has rejected the
packet. Similarly, clearing every bit in the Hash Table
registers means that the filter criteria will never be met,
so all packets will be passed on to the next lower
priority filter.
This filter is disabled at power-up. To enable this filter,
set HTEN (ERXFCON<15>). If the filter is disabled, all
frames will be passed on to the next lower priority filter,
regardless of destination address or Hash Table
register values.
EXAMPLE 10-1:
Packet Destination Address:
01-00-00-00-01-2C (hex)
Result of CRC-32 with 4C11DB7h:
1101 1010 0000 1011 0100 0101 0111 0101
(binary)
Pointer Derived from bits<28:23> of CRC Result:
110100 (binary) or 34 (hex)
Corresponding Hash Table Location:
EHT4<4>
07
17
27
37
7
06
16
26
36
6
05
15
25
35
5
DERIVING A HASH TABLE
LOCATION
 2010 Microchip Technology Inc.
04
14
24
34
4
03
13
23
33
3
02
12
22
32
2
01
21
31
11
1
00
10
20
30
0