AN2692 Freescale Semiconductor / Motorola, AN2692 Datasheet - Page 21

• Manufacturer Part Number: AN2692
• Description: MC9S12NE64 Integrated Ethernet Controller
• Manufacturer: Freescale Semiconductor / Motorola

Promiscuous Filter Mode
Promiscuous filtering mode is set using the PROM of the RXCTS register.
Setting the MC9S12NE64 to enable promiscuous mode is useful for diagnosing network issues, but it can
overburden the MCU.
Ethertype Filtering
Ethertype filtering is provided as an additional means to reduce MC9S12NE64 CPU use. This feature
uses the internal EMAC state machine to automatically filter-out and ignore incoming Ethernet packets
before the packet is accepted by the EMAC buffer. It also indicates to the CPU that a packet is received
without using any CPU cycles.
Ethertype (ETYPE) register. If any ETCTL register bit is set, the Ethertype filter is enabled.
Ethertype filtering is based on filtering an incoming Ethernet packet’s length/type data field in the MAC
header.
structure.
source address.
Freescale Semiconductor
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Reset:
Read:
Write:
PROM = 0 — Unicast, broadcast, and multicast filtering modes behave as described in the
previous section
PROM = 1 — Promiscuous mode is enabled and all frames are accepted, regardless of address
Figure 15
Figure 15
15
0
14
0
shows the position of the 2-byte length/type data field in the standard Ethernet packet
shows that the length/type data is a part of the MAC header after the MAC hardware
13
0
Reset:
Figure 13. Ethertype Control (ETCTL) Register
Read:
Write:
MC9S12NE64 Integrated Ethernet Controller, Rev. 0.2
12
0
Figure 13
Figure 14. Ethertype (ETYPE) Register
11
FPET
0
Bit 7
0
10
0
is the Ethertype control (ETCTL) register, and
= Unimplemented
6
0
0
9
0
8
0
ETYPE
5
0
0
MC9S12NE64 Ethernet Media Access Controller (EMAC)
0
7
FEMW
4
0
6
0
FIPV6
5
0
3
0
0
4
FARP
2
0
3
0
Figure 14
FIPV4
0
2
1
0
1
0
FIEEE
Bit 0
is the
0
0
0
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