mcf5272 Freescale Semiconductor, Inc, mcf5272 Datasheet - Page 231

• Manufacturer Part Number: mcf5272
• Description: Mcf5272 Coldfire Integrated Microprocessor User
• Manufacturer: Freescale Semiconductor, Inc

MOTOROLA
(EIR[RFINT], maskable by EIMR[RFIEN]), indicating that a frame has been received and
is in memory. The FEC then waits for a new frame. The FEC receives serial data lsb first.
11.4.2 CAM Interface
In addition to the FEC address recognition logic, an external CAM may be used for frame
reject with no additional pins other than those in the MII interface. This CAM interface is
documented in an application note titled “Using Motorola’s Fast Static RAM CAMs with
the MPC860T’s Media Independent Interface,” located at the following URL:
http://www.mot.com/SPS/RISC/netcomm/aesop/mpc8XX/860/860tcam.pdf.
11.4.3 Ethernet Address Recognition
The FEC filters the received frames based on the type of destination media access controller
address (hardware address). There are three destination address (DA) types:
The difference between an individual address and a group address is determined by the I/G
bit in the destination address field. A flowchart for address recognition on received frames
is illustrated in Figure 11-4 and summarized in Table 11-3.
In promiscuous mode (PROM = 1 in RCR), the FEC receives all of the incoming frames
regardless of their address. In this mode, the destination address lookup is still performed
and RxBD[MISS] is set accordingly. If address recognition did not achieve a match, the
frame is received with RxBD[MISS] set. If address recognition achieves a match, the frame
is received without setting RxBD[MISS].
Address Type
.
Destination
broadcast
individual
• Individual (unicast)
• Group (multicast)
• Broadcast (all-ones group address)
group
The FEC compares the destination address field of the received frame with the 48-bit MAC address
programmed into MALR and MAUR.
The FEC determines whether or not the group address is a broadcast address. If not broadcast, a
hash table lookup is performed using the 64-entry hash table defined in HTLR and HTUR.
The frame is accepted unconditionally.
Table 11-3. Ethernet Address Recognition
Chapter 11. Ethernet Module
FEC Address Processing
FEC Frame Transmission
11-7