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參數(shù)資料
| 型號(hào)： | MT90221 |
| 廠商： | Mitel Networks Corporation |
| 英文描述： | Quad IMA/UNI PHY Device(四端口 IMA/UNI 物理層設(shè)備（四端口ATM IMA和UNI處理器）) |
| 中文描述： | 四IMA的/單向物理層設(shè)備（IMA的四端口/單向物理層設(shè)備（四端口自動(dòng)柜員機(jī)IMA的和單向處理器）） |
| 文件頁數(shù)： | 23/116頁 |
| 文件大?。?/td> | 309K |
| 代理商： | MT90221 |
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MT90221
15
ATM cells received from the ATM port are placed in a
TX UTOPIA FIFO, waiting to be transmitted. If the
Idle/Unassigned cell removal option is selected,
these cells are dropped. If the TX UTOPIA FIFO is
empty, an Idle cell is sent to the output link. The
content of the Idle cell is pre-initialized with the
header bytes set at 0x00, 0x00, 0x00 and 0x01. The
payload bytes are set to 0x6A.
TX UTOPIA FIFO Length Definition
registers are
used to set the TX UTOPIA FIFO size. The total
number of cells in all the TX UTOPIA FIFOs and TX
Link FIFO (includes the links used in IMA Mode and
the links used in UNI Mode) is limited to 58.
Idle Cells are transmitted on the UNI PCM Interface
until the bit corresponding to the link in the
UTOPIA
Input Link PHY Enable
register is set. Then, the
ATM User cells are transferred from the Input
UTOPIA port to the TX PCM port.
3.0 The ATM Receive Path
The receive path corresponds to the cell flow from
the T1/E1 interfaces to the ATM UTOPIA Interface.
The MT90221 provides cell delineation and optional
cell filtering to discard Unassigned or Idle cells on
each link. The incoming cells are stored in the
external RAM required in IMA mode to perform cell
recovery due to delay variation between the links
introduced by the network.
3.1
This block provides the circuitry necessary to
perform functions such as Cell Delineation (CD), cell
payload de-scrambling, HEC verification and filtering
of Idle (UNI) cells. The CD circuit delineates ATM
cells received from the payload of the T1 or E1 frame
through the PCM Interface.
Cell Delineation Function
When
calculations
performing
are
delineation,
interpreted
correct
indicate
HEC
cell
to
boundaries. The CD circuit performs a sequential
byte by byte hunt for a correct HEC sequence. While
performing this hunt, the cell delineation state
machine is in the HUNT state. Figure 5 depicts a
state diagram of the cell delineation operation.
Figure 5 - Cell Delineation State Diagram
When a correct HEC is found, the CD circuit locks on
the cell boundary and enters the PRESYNC state.
The PRESYNC state keeps checking the HEC to
ensure that the previous indication was not false.
False indications are interpreted to mean the circuit
is not tracking good ATM cells. After entering the
PRESYNC state, the first false indication triggers a
transition back to HUNT state.
If the PRESYNC state HEC is correct, then a
transition to the SYNC state occurs after “
δ
” cells
(DELTA in ITU I.432) are correctly received. In the
SYNC state, the CD circuit treats the incoming ATM
cell stream as stable and the MT90221 functions
normally.
While in the SYNC state, if an incorrect HEC is
obtained “a” consecutive times (ALPHA in ITU I.432),
cell delineation is considered lost and a transition is
made back to the HUNT state (see Figure 6).
As defined by the ITU I.432 recommendations, the
value of ALPHA and DELTA determine the
robustness of the delineation method. The value of
ALPHA and DELTA for the Cell Delineation state
machine are defined in the
Cell Delineation
register.
HUNT
Correct HEC (byte by byte)
PRESYNC
SYNC
ALPHA
Consecutive
Incorrect HEC
(cell by cell)
DELTA Consecutive
Correct HEC
(cell by cell)
Incorrect HEC
(cell by cell)
Figure 4 - Functional Block Diagram of the Transmitter in UNI Mode
(For Link[N] where 1
≤
N
≤
4)
ATM In
Cell_In_Control
Cell RAM
Tx Link [N] FIFO
P/S
Link [N]
Serial
Streams
Transmitter
Output Controller and
Cell Distribution
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MT90221AL | 制造商:MITEL 制造商全稱:Mitel Networks Corporation 功能描述:Quad IMA/UNI PHY Device |
| MT90222 | 制造商:ZARLINK 制造商全稱:Zarlink Semiconductor Inc 功能描述:4/8/16 Port IMA/TC PHY Device |
| MT90222AG | 制造商:Microsemi Corporation 功能描述:ATM IMA 40MBPS 2.5V 384BGA - Trays |
| MT90222AG2 | 制造商:Microsemi Corporation 功能描述:ATM IMA 40MBPS 2.5V 384BGA /BAKE/DRYPACK - Trays |
| MT90223AG | 制造商:Microsemi Corporation 功能描述:ATM IMA 80MBPS 2.5V 384BGA - Trays |
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