mt90520 Zarlink Semiconductor, mt90520 Datasheet - Page 45

• Manufacturer Part Number: mt90520
• Description: 8-port Primary Rate Circuit Emulation Aal1 Sar
• Manufacturer: Zarlink Semiconductor

•
The size of the SDT Reassembly Circular Buffers is variable, and there is one buffer for each TDM channel. For
more details regarding fields of the SDT Reassembly Circular Buffers, refer to page 81.
TDM SDT Reassembly Control Structure
Each TDM SDT Reassembly Control Structure is used to determine which TDM output channels of a particular port
are valid, which ones are idle and whether to report underruns on particular channels. There is one entry per
channel and one Control Structure per port. The TDM SDT Reassembly Control Structures are located in internal
memory at byte addresses A0000h + p*800h. The format of the 16-bit entries is shown in Figure 13.
The Reassembly Circular Buffer Address field in each entry tells the hardware where the reassembly data and CAS
are located (points to the location of the per-channel SDT Reassembly Circular Buffers in external memory). These
addresses in external memory are formed using the TDM_REASS_BASE_ADD field (located in TDM Control
Register 3) and the addresses programmed in the TDM SDT Reassembly Control Structure. Refer to Table 11 for
more information on how the addresses are formed.
TDM Byte - This field contains the TDM data bytes which are extracted from received cells. If dummy cells
have been inserted, this field contains the value of the dummy data programmed by the user.
MF
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
Figure 12 - Per-Channel SDT Reassembly Circular Buffer
Res
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Turn
0 1
0 1
0 1
0 1
0 1
0 1
0 1
0 1
0 1
0 1
0 1
0 1
0 1
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
Zarlink Semiconductor Inc.
A B C D
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CAS
MT90520
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0 0 1 0 1 0 1 0
TDM Byte
Data Sheet