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Serial Communication Controllers (SCCs)
MC68360 USER’S MANUAL
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 = When this buffer is serviced by the CP, TX, or TXE bit in the transparent event reg-
ister will be set. The TX and TXE bits can cause interrupts if they are enabled.
L—Last in Message
0 = The last byte in the buffer is not the last byte in the transmitted transparent frame.
Data from the next transmit buffer (if ready) will be transmitted immediately follow-
ing the last byte of this buffer.
1 = The last byte in the buffer is the last byte in the transmitted transparent frame. After
this buffer is transmitted, the transmitter will require synchronization before the
next buffer will be transmitted.
TC—Transmit CRC
0 = No CRC sequence will be transmitted after this buffer.
1 = A frame check sequence as defined by the TCRC bits in the GSMR will be trans-
mitted after the last byte of this buffer.
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.
However, the R-bit will be cleared if an error occurs during transmission, regard-
less of the CM bit.
UN—Underrun
The SCC encountered a transmitter underrun condition while transmitting the associated
data buffer.
CT—CTS Lost
CTS was lost during frame transmission.
Data Length
The data length is the number of bytes that the CP should transmit from this BD’s data
buffer. The data length, which should be greater than zero, may be even or odd. This val-
ue is never modified by the CP.
Tx Data Buffer Pointer
The transmit buffer pointer, which always points to the first byte of the associated data
buffer, may be even or odd. The buffer may reside in either internal or external memory.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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