Serial Communication Controllers (SCCs)
MOTOROLA
MC68360 USER’S MANUAL
7-161
NOTE: Entries in boldface must be initialized by the user.
E—Empty
0 = The data buffer associated with this Rx BD has been filled with received data, or
data reception has been aborted due to an error condition. The CPU32+ core is
free to examine or write to any fields of this Rx BD. The CP will not use this BD
again while the E-bit remains zero.
1 = The data buffer associated with this BD is empty, or reception is currently in
progress. This Rx BD and its associated receive buffer are owned by the CP. Once
the E-bit is set, the CPU32+ core should not write any fields of this Rx BD.
Bits 14, 6, 2—Reserved
W—Wrap (Final BD in Table)
0 = This is not the last BD in the Rx BD table.
1 = This is the last BD in the Rx 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 RBASE).
The number of Rx 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.
I—Interrupt
0 = No interrupt is generated after this buffer has been filled.
1 = The RX bit in the UART event register will be set when this buffer has been com-
pletely filled by the CP, indicating the need for the CPU32+ core to process the
buffer. The RX bit can cause an interrupt if it is enabled.
C—Control Character
0 = This buffer does not contain a control character.
1 = This buffer contains a control character. The last byte in the buffer is one of the
user-defined control characters.
A—Address
0 = The buffer contains data only.
1 = When working in non-automatic multidrop mode, this bit indicates that the first byte
of this buffer contains an address byte. The address comparison should be imple-
mented in software. In automatic multidrop mode, this bit indicates that the BD con-
tains a message received immediately after an address recognized in UADDR1 or
UADDR2. This address is not written into the receive buffer.
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
OFFSET + 0
E
—
W
I
C
A
CM
ID
AM
—
BR
FR
PR
—
OV
CD
OFFSET + 2
DATA LENGTH
OFFSET + 4
RX DATA BUFFER POINTER
OFFSET + 6