MC68000 MOTOROLA [Motorola, Inc], MC68000 Datasheet - Page 449

• Manufacturer Part Number: MC68000
• Manufacturer: MOTOROLA [Motorola, Inc]

Bits 7, 6, 2—Reserved for future use
BR—Break Received
FR—Framing Error
PR—Parity Error
OV—Overrun
CD—Carrier Detect Lost (valid only in NMSI mode)
E.2.1.4.2 Receive Buffer Data Length. This 16-bit value is written by the IMP to indicate
the number of octets received into the data buffer.
E.2.1.4.3 Receive Buffer Pointer. This 32-bit value is written by the user to indicate the
address where the data is to be stored.
E.2.1.5 TRANSMIT BUFFER DESCRIPTORS. Each SCC has eight transmit buffer
descriptors. Each buffer descriptor consists of four words as shown below. Reserved bits in
registers should be written as zeros.
E.2.1.5.1 Transmit BD Control/Status Word. To initialize the buffer, the user should write
bits 15-9 and clear bit 0. The IMP clears bit 15 when the buffer is transmitted or closed due
to an error and sets bit 0 depending on which error occurred.
R—Ready
MOTOROLA
OFFSET + 0
OFFSET +2
OFFSET +4
OFFSET +6
0 = No break sequence was detected during reception into this buffer.
1 = A break sequence was detected during reception into this buffer.
0 = No framing error was detected.
1 = A framing error was detected during reception of the last data byte in this buffer.
0 = No parity error was detected.
1 = A character with a parity error was received and is located in the last byte of this
0 = No receiver overrun occurred.
1 = A receiver overrun condition occurred during buffer reception.
0 = No CD lost was detected.
1 = CD was negated during buffer reception.
0 = This data buffer is not currently ready for transmission.
1 = This data buffer has been prepared by the user for transmission but has not yet
buffer.
been fully transmitted. Must be set by the user to enable transmission of the buffer.
15
R
14
X
13
W
12
I
CR
11
MC68360 USER’S MANUAL
10
A
9
P
TX BUFFER POINTER
DATA LENGTH
—
8
—
7
—
6
—
5
SCC Programming Reference
—
4
—
3
—
2
—
1
E-27
CT
0