AN2692 Freescale Semiconductor / Motorola, AN2692 Datasheet - Page 22

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

MC9S12NE64 Ethernet Media Access Controller (EMAC)
Ethertype filtering allows only packets with an approved type/length field value to be accepted by the
MC9S12NE64 filter. Multiple Ethertype filtering targets can be designated in ETCTL register. The ETCTL
register provides five fixed Ethertype targets and one programmable Ethertype target. The available
filtering targets include:
Configuring Ethernet Buffers and Maximum Frame Length Settings
The MC9S12NE64 has 8K of RAM that is available and shared between user RAM and the EMAC
Ethernet buffer space. The EMAC Ethernet buffer space consists of three buffers, which contain:
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FPET (programmable Ethertype) — If this filter target is used (FPET = 1), a 2-byte value for an
Ethertype filter target must be provided using the ETYPE register
FEMW (emWare data type) — Ethertype value of 0x8876
FIPV6 (Internet protocol version 6) — Ethertype value of 0x86DD
FARP (address resolution protocol) — Ethertype value of 0x0806
FIPV4 (Internet protocol version 4) — Ethertype value of 0x0800
FIEEE (IEEE 802.3 length field) — Length data field that ranges from 0x0000 to 0x05DC
One transmit buffer — The user must store the following data in the transmission buffer to prepare
a data packet for transmission:
–
–
–
–
Destination address
Source address
Type/length
Data
Figure 15. Format and Content of Ethernet Packets (Repeated)
ENCAPSULATED DATA
MC9S12NE64 Integrated Ethernet Controller, Rev. 0.2
(LAYER 3 AND UP)
MAC HEADER
MAC TRAILER
46 TO 1500
BYTES
7 BYTES
1 BYTES
6 BYTES
6 BYTES
2 BYTES
4 BYTES
START DELIMITER
MAC ADDRESS
MAC ADDRESS
FRAME CHECK
LENGTH/TYPE
DESTINATION
SEQUENCE
PREAMBLE
SOURCE
DATA
FIELD
FIELD
PAD
10101010
10101011
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