mpc823rg Freescale Semiconductor, Inc, mpc823rg Datasheet - Page 548

• Manufacturer Part Number: mpc823rg
• Description: Mpc823 Powerquicc Integrated Communications Processor For Portable Systems
• Manufacturer: Freescale Semiconductor, Inc

Communication Processor Module
16.6.3.5 IDMA BUFFER DESCRIPTORS. The special IDMA buffer descriptors present the
source addresses, destination addresses, and byte counts to the RISC microcontroller. The
RISC microcontroller reads the buffer descriptors, programs the SDMA channel, and notifies
the core about the completion of a buffer transfer using the IDMA buffer descriptors. This
process is similar to that of the serial channels, except that the buffer descriptor is larger
because it contains additional information.
You must prepare the following bits before a transfer can occur. They are set by the RISC
microcontroller after the buffer has been transferred.
V—Valid
NOTE: You are only responsible for initializing the items in bold.
OFFSET + A
OFFSET + C
OFFSET + E
OFFSET + 0
OFFSET + 2
OFFSET + 4
OFFSET + 6
OFFSET + 8
0 = The data buffers associated with this buffer descriptor are not currently ready for
1 = You have prepared the data buffers for transfer. Notice that only one data buffer
transfer. You are free to manipulate this buffer descriptor or its associated data
buffer. When it is not in autobuffer mode, the RISC microcontroller clears this bit
after the buffer has been transferred (or after an error condition is encountered).
must be prepared if the source/destination is a peripheral device. It can only be the
source data buffer when the destination is a device or the destination data buffer
when the source is a device. You can not write any fields of this buffer descriptor
once this bit is set.
0
V
Note: The only difference between autobuffer mode and buffer-chaining mode is that
RES
1
W
the V bit is not cleared by the RISC microcontroller in autobuffer mode.
Autobuffer mode is enabled by the CM bit.
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For More Information On This Product,
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MPC823 REFERENCE MANUAL
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DESTINATION DATA BUFFER POINTER
RES
5
SOURCE DATA BUFFER POINTER
CM
6
DATA LENGTH
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8
9
10
RESERVED
11
SFCR
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MOTOROLA
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