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Serial Communication Controllers (SCCs)
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MC68360 USER’S MANUAL
erenced by the channel’s Tx BD table. The Ethernet controller confirms transmission or indi-
cates error conditions using the BDs to inform the host that the buffers have been serviced.
NOTE: Entries in boldface must be initialized by the user.
R—Ready
0 = The data buffer associated with this BD is not ready for transmission. The user is
free to manipulate this BD or its associated data buffer. The CP clears this bit after
the buffer has been transmitted or after an error condition is encountered.
1 = The data buffer, which has been prepared for transmission by the user, has not
been transmitted or is currently being transmitted. No fields of this BD may be writ-
ten by the user once this bit is set.
PAD—Short Frame Padding
This bit is valid only when the L-bit is set; otherwise, it is ignored.
0 = Do not add PADs to short frames.
1 = Add PADs to short frames. Pad bytes will be inserted until the length of the trans-
mitted frame equals the MINFLR. The PAD bytes are stored in PADs in the param-
eter RAM.
W—Wrap (Final BD in Table)
0 = This is not the last BD in the Tx BD table.
1 = This is the last BD in the Tx BD table. After this buffer has been used, the CP will
receive incoming data into the first BD in the table (the BD pointed to by TBASE).
The number of Tx BD s in this table is programmable and is determined only by the
W-bit and the overall space constraints of the dual-port RAM.
NOTE
The TxBD table must contain more than one BD in Ethernet
mode.
I—Interrupt
0 = No interrupt is generated after this buffer has been serviced.
1 = The TXB bit or TXE bit will be set in the Ethernet event register after this buffer has
been serviced. These bits can cause interrupts if they are enabled.
L—Last
0 = This is not the last buffer in the transmit frame.
1 = This is the last buffer in the current transmit frame.
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9876543210
OFFSET + 0
R
PAD
W
I
L
TC
DEF
HB
LC
RL
RC
UN
CSL
OFFSET + 2
DATA LENGTH
OFFSET + 4
TX DATA BUFFER POINTER
OFFSET + 6
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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