Motorola PowerQUICC II MPC8280 Series Reference Manual page 839

Command
When used with the Ethernet controller, this command violates a specific behavior of an Ethernet/IEEE
STOP
802.3 station. It should not be used.
TRANSMIT
Used to ensure that transmission stops smoothly after the current frame finishes or has a collision.
GRACEFUL
SCCE[GRA] is set once transmission stops, at which point Ethernet transmit parameters and their BDs
STOP
can be updated. TBPTR points to the next TxBD. Transmission begins once the R bit of the next BD is
TRANSMIT
set and a
RESTART TRANSMIT
Note that if
GRACEFUL STOP TRANSMIT
to the start of the collided frame with the R bit still set in the BD. The frame looks as if it was never sent.
Enables transmission of characters on the transmit channel. The Ethernet controller expects it after a
RESTART
TRANSMIT GRACEFUL STOP TRANSMIT
transmission from the current TBPTR in the channel TxBD table.
Initializes transmit parameters in this serial channel parameter RAM to reset state. Issue only when the
INIT TX
transmitter is disabled.
PARAMETERS
Table 25-3 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
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.
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 Section 25.21, "SCC Ethernet Programming
Example."
MOTOROLA
Freescale Semiconductor, Inc.
Table 25-2. Transmit Commands
command is issued.
is issued and the current frame ends in a collision, TBPTR points
command is issued or a transmitter error. The Ethernet controller resumes
and
INIT TX RX PARAMETERS
Table 25-3. Receive Commands
command is generally used to force the Ethernet receiver to stop
ENTER HUNT MODE
and
INIT TX RX PARAMETERS
NOTE
Chapter 25. SCC Ethernet Mode
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SCC Ethernet Commands
Description
resets both transmit and receive parameters.
Description
resets receive and transmit parameters.
25-11