Freescale Semiconductor PowerQUICC MPC885 Reference Manual page 767

Table 27-4 describes receive commands.
Command
After hardware or software is reset and the channel is enabled in GSMR_L, the channel is in receive
ENTER HUNT
enable mode and uses the first BD in the table. The receiver then enters hunt mode, waiting for an
MODE
incoming frame. The
stop receiving the current frame and enter hunt mode, in which the ethernet controller continually scans
the input data stream for a transition of carrier sense from inactive to active and then a preamble
sequence followed by the start frame delimiter. After receiving the command, the buffer is closed and
the CRC calculation is reset. The next RxBD is used to receive more frames.
Should not be used with the ethernet controller.
CLOSE RXBD
Initializes receive parameters in this serial channel parameter RAM to their reset state. Issue it only
INIT RX
when the receiver is disabled.
PARAMETERS
Used to set one of the 64 bits of the four individual/group address hash filter registers. The address to
SET GROUP
be added to the hash table should be written to TADDR_L, TADDR_M, and TADDR_H in the parameter
ADDRESS
RAM before executing this command. The CP uses an individual address if the I/G bit in the address
stored in TADDR is 0; otherwise, it uses a group address. This command can be executed at any time,
regardless of whether the ethernet channel is enabled.
To delete an address from the hash table, disable the ethernet channel, clear the hash table registers,
and execute this command for the remaining addresses. Do not simply clear the channel's associated
hash table bit because the hash table may have multiple addresses mapped to the same hash table bit.
Note that after a CPM reset via CPCR[RST], the ethernet transmit enable (TENA) signal defaults to its
RTS, active-low functionality. To prevent false TENA assertions to an external transceiver, configure
TENA as an input before issuing a CPM reset. See step 3 in
Example."
27.10 SCC Ethernet Address Recognition
The ethernet controller can filter received frames based on different addressing types—physical
(individual), group (multicast), broadcast (all-ones group address), and promiscuous. 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 shown in
In the physical type of address recognition, the ethernet controller compares the destination address field
of the received frame with the user-programmed physical address in PADDR1. Address recognition can
be performed on multiple individual addresses using the IADDR1–4 hash table.
Freescale Semiconductor
Table 27-4. Receive Commands
command is generally used to force the ethernet receiver to
ENTER HUNT MODE
and
INIT TX RX PARAMETERS
MPC885 PowerQUICC Family Reference Manual, Rev. 2
Description
resets receive and transmit parameters.
Section 27.21, "SCC Ethernet Programming
Figure
SCC Ethernet Mode
27-4.
27-11