Datasheet

____________________________________________________ DS34T101, DS34T102, DS34T104, DS34T108
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Figure 10-49. TDM-over-Packet Data Flow Diagram
10.6.11.1 Buffer Descriptor
Data is transferred between the Ethernet MAC, internal payload-type machines and the external CPU by means of
buffers in the SDRAM. Payload data is stored in 2 kB SDRAM buffers along with a buffer descriptor located in the
buffer’s first dwords. The buffer pointers are managed inside the TDMoP block and are stored in queues, pools,
and other internal blocks. Queues store pointers to SDRAM buffers containing packet data to be processed, while
pools store pointers to empty buffers. The pointers are passed from one block to another. Only the block owning
the pointer can access the associated buffer.
The size of the buffer descriptor size depends on the internal path it is used for:
TDM  TDM, TDM  CPU and CPU  TDM: One dword
TDM  ETH, CPU  ETH and ETH  TDM: Two dwords
ETH  CPU: Three dwords
The fields of the buffer descriptor dwords are described in the sections below.