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Serial Communication Controllers (SCCs)
7-214
MC68360 USER’S MANUAL
The status and control bits are prepared by the user before transmission and are set by the
CP after the buffer has been transmitted.
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.
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 = Either TX or TXE in the BISYNC event register will be set when this buffer has been
serviced by the CP, which can cause an interrupt.
L—Last in Message
0 = The last character in the buffer is not the last character in the current block.
1 = The last character in the buffer is the last character in the current block. The trans-
mitter will enter (remain in) normal mode after sending the last character in the buff-
er and the BCS (if enabled).
TB—Transmit BCS
This bit is valid only when the L-bit is set.
0 = Transmit the SYN1–SYN2 sequence or idle (according to the RTSM bit in the
GSMR) after the last character in the buffer.
1 = Transmit the BCS sequence after the last character. The BISYNC controller will
also reset the BCS generator after transmitting the BCS.
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.
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14
13
12
11
10
9876543210
OFFSET + 0
R
—
WI
L
TB
CM
BR
TD
TR
B
—
UN
CT
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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