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CHAPTER 4 ATM CELL PROCESSOR
268
Preliminary User’s Manual S14767EJ1V0UM00
UTOPIA I/F Control block has a four-cell-depth FIFO for each transmission and reception. The last cell in Tx
FIFO and the first cell in Rx FIFO are mapped to V
R
4120A RISC Processor/ RISC Core memory space.
UTOPIA 2 I/F is an 8-bit bus I/F to PHY devices, which is defined in a ATM Forum document, “ATM-PHY-0039”.
UTOPIA MGR I/F will be supported as well.
Its features are as follows:
- It supports up to 16 PHY devices at a time. Either PHY addresses from zero through fifteen or from sixteen
through thirty can be selected by setting command register.
- The first word of cell header and the last two word of payload can be read in Big-Endien byte order to
insert/extract some special bit-fields.
- In Tx side, it generates payload for an idle cell and an unassigned cell automatically when detects their pre-
determined header pattern.
- To avoid Head-of-line Blocking, later cells can pass earlier cells if their destination PHY devices are not ready.
- In Rx side, it filters out idle cells and unassigned cells when detects their pre-determined header pattern.
UTOPIA Level2 data path interface as a physical layer data interface
UTOPIA Level2 management interface as a physical layer management interface
CRC32/CRC10 calculator & checker
UTOPIA Bus Controller block has the CRC32 calculator for each transmission and reception. CRC32 value is
calculated for every packet. For transmission, CRC32 value is inserted into the CRC32 field in trailer. For
reception, CRC32 value is compared with the value in the CRC32 field in trailer, in order to check whether any
errors occurred or not.
UTOPIA Bus Controller block has CRC10 calculator for each transmission and reception, too. It can be selected
if CRC10 is inserted to the payload or not. CRC10 value is calculated for every cell. For transmission, CRC10
value is inserted into the last 10-bit area of the payload if selected. For reception, CRC10 value is compared with
the value in the last 10-bit of the payload if selected.
4.1.2.4 Other blocks
Register set is similar to that of the
μ
PD98401A/
μ
PD98405. Work-RAM is 12K-byte memory. It is shared between
RISC Core and UTOPIA Bus Controller block. It also can be accessed by V
R
4120A RISC Processor, using Indirect-
Access. Tables and Pool Descriptors are located in this RAM.
IBUS is a 32-bit PCI-like bus.