MC68MH360RC25L Freescale Semiconductor, MC68MH360RC25L Datasheet - Page 71

• Manufacturer Part Number: MC68MH360RC25L
• Description: IC MPU QUICC 25MHZ 241-PGA
• Manufacturer: Freescale Semiconductor

Specifications of MC68MH360RC25L

• Processor Type: M683xx 32-Bit
• Speed: 25MHz
• Voltage: 5V
• Mounting Type: Surface Mount
• Package / Case: 241-PGA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -

Chapter 5
Buffer Descriptors
50
50
QMC buffer descriptors are located within 64 Kbytes in external memory; see Figure 2-2.
Each buffer descriptor contains key information about the buffer it defines.
The first two sections describe the contents of the receive and transmit buffer descriptors
for the QMC protocol.
The third section discusses the placement of QMC and non-QMC buffer descriptors in
internal and external memory.
5.1 Receive Buffer Descriptor
Figure 5-1 shows a receive buffer descriptor.
Table 5-1 describes the individual fields of a receive buffer descriptor. Boldfaced entries
must be initialized by the user.
0
OFFSET + 0
OFFSET + 2
OFFSET + 4
OFFSET + 6
Field
Notes: For the 68360, the bit numbering is reversed. See Appendix A for more information.
Name
E
Entries in boldface must be initialized by the user.
Table 5-1. Receive Buffer Descriptor (RxBD) Field Descriptions
E
0
Empty
0 The data buffer associated with this buffer descriptor has been filled with received data, or
1 The data buffer associated with this buffer descriptor is empty, or reception is currently in
data reception has been aborted due to an error. The core is free to examine or write to any
field of this RxBD. The CPM does not use this buffer descriptor again while the empty bit
remains zero.
progress. This RxBD and its associated receive buffer are owned by the CPM. If E = 1, the
CPU core should not write to any field of this RxBD.
—
1
Freescale Semiconductor, Inc.
Figure 5-1. Receive Buffer Descriptor (RxBD)
For More Information On This Product,
W
2
3
I
Go to: www.freescale.com
Chapter 5. Buffer Descriptors
4
L
5
F
Rx DATA BUFFER POINTER
CM
6
DATA LENGTH
Description
—
7
UB
8
—
9
LG
10
NO
11
AB
12
CR
13
14
—
15
—