28478G-18 Mindspeed Technologies, 28478G-18 Datasheet - Page 108

• Manufacturer Part Number: 28478G-18
• Description: Multichannel Synchronous Communications Controller 208-Pin BGA
• Manufacturer: Mindspeed Technologies

Specifications of 28478G-18

• Package: 208BGA
• Maximum Data Rate: 32768 Kbps
• Transmission Media Type: Wire
• Power Supply Type: Analog
• Typical Supply Current: 250 mA
• Typical Operating Supply Voltage: 3.3 V
• Minimum Operating Supply Voltage: 3 V
• Maximum Operating Supply Voltage: 3.6 V

A head pointer allows the host to specify a new list of descriptors to use for channel processing. This mechanism
can be used after a reset to kick-start or reactivate channel processing which has completely processed the current
list of descriptors.
A head pointer also allows the host to generate a new list of descriptors in memory before performing a list
transition; that is, while MUSYCC processes data in one list, the host can process data in a separate list, and,
when appropriate, can switch the lists.
Table 5-20.
5.2.4.4
The message pointer points to the current message descriptor being serviced. This pointer is maintained in a fixed
memory location relative to a Group Base Pointer in shared memory.
Table 5-21
Table 5-21.
5.2.4.5
The Message Descriptor is pointed to by the Message Pointer and the Head Pointer and is maintained in a variable
location in shared memory. A Message Descriptor includes the following fields:
•
•
•
•
5.2.4.6
The Buffer Descriptor is the first dword of a Message Descriptor after the host has prepared the data structures in
memory. All Buffer Descriptors include the following fields:
•
•
•
28478-DSH-002-E
Table 5-20
Field
Field
31:2
31:2
Buffer Descriptor (when host writes)
Buffer Status Descriptor (when MUSYCC writes)
Data Buffer Pointer
Next Descriptor Pointer
Owner Indicator Bit (OWNER)
No Poll/Poll Indicator (NP)
End of Buffer Interrupt Enable (EOBI)
Bit
1:0
Bit
1:0
lists the message pointers and their descriptions.
lists the head pointers and their descriptions.
HEADPTR[29:0]
MSGPTR[29:0]
HEADPTR[1:0]
Head Pointer
Message Pointer
MSGPTR[1:0]
Name
Name
Message Pointer
Message Descriptor
Buffer Descriptor
Preliminary Information / Mindspeed Proprietary and Confidential
Value
Value
—
—
0
0
Mindspeed Technologies
These 30 bits are appended with 00b to form a dword-aligned 32-bit address. This address
points to the first Message Descriptor in a list of descriptors.
Ensures dword alignment.
These 30 bits are appended with 00b to form a dword-aligned 32-bit address. This word pointer
points to the first dword of a Message Descriptor.
Ensures dword alignment.
®
Description
Description
Memory Organization
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