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Serial Management Controllers (SMCs)
MC68360 USER’S MANUAL
channel’s Tx BD ring. The CP confirms transmission or indicates error conditions via the
BDs to inform the processor 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.
Bits 14, 11, 10, 7–0—Reserved
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 BDs in this table is programmable and is determined only by the
W-bit and the overall space constraints of the dual-port RAM.
I—Interrupt
0 = No interrupt is generated after this buffer has been serviced.
1 = The TX bit in the SMC UART event register will be set when this buffer has been
serviced. TX can cause an interrupt if it is enabled.
CM—Continuous Mode
0 = Normal operation.
1 = The R-bit is not cleared by the CP after this BD is closed, allowing the associated
data buffer to be retransmitted automatically when the CP next accesses this BD.
P—Preamble
0 = No preamble sequence is sent.
1 = The UART will send one all-ones character before sending the data so that the oth-
er end will detect an idle line before the data is received. If this bit is set and the
data length of this BD is zero, only a preamble will be sent.
15
14
13
12
11
10
9876543210
OFFSET + 0
R
—
WI
——
CM
P
————————
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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