Serial Management Controllers (SMCs)
MOTOROLA
MC68360 USER’S MANUAL
7-301
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, 10, 8–2, 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 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 or TXE bit in the event register will be set when this buffer has been ser-
viced. TX and TXE 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 this 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.
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.
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
OFFSET + 0
R
—
W
I
L
—
CM
—
—
—
—
—
—
—
UN
—
OFFSET + 2
DATA LENGTH
OFFSET + 4
TX DATA BUFFER POINTER
OFFSET + 6