ZL30226/GA ZARLINK [Zarlink Semiconductor Inc], ZL30226/GA Datasheet - Page 47

• Manufacturer Part Number: ZL30226/GA
• Description: 4/8/16 Port IMA/TC PHY Device for xDSL
• Manufacturer: ZARLINK [Zarlink Semiconductor Inc]

3.3.6
A link is declared out of IMA Frame (LIF) synchronization state when the IFSM goes in HUNT mode for ’gamma +2’
frames after it was in SYNC state. Loss of IMA Frame (LIF) and end of LIF can optionally generate an interrupt
(IRQ). This condition is latched in bits 2 and 10 of the IRQ Link Status (0x0435-0x0444) registers. Refer to section
6.2.2 IRQ Link Status and IRQ Link Enable Registers for more details.
The LIF status bit reports the current condition of the IMA Frame State Machine at the time it is read.
3.3.7
The ZL30226/7/8 scans each incoming cell received for the Filler Cell Indication code. Filler cells are written to
external RAM to keep the IMA frame aligned. They are automatically discarded after being read from the external
RAM by the recombiner.
3.3.8
Each incoming ICP cell received is scanned for the Stuff Indication Code. Stuff cells are inserted at the transmit end
as two identical and consecutive ICP cells with the Link Stuff Indication Bits set as defined in the IMA specification.
The ZL30226/7/8 automatically discards one of the two Stuff cells without storing it in external RAM. The other is
kept and processed as a regular ICP cell. IMA Frame synchronization is maintained for all cases (except case 7,
O-19 optional requirements) as described in Figure 20 of the IMA Specification.
3.3.9
An internal buffer is implemented to collect cells from the RX TDM links for analysis by the software. This storage
unit has a circular buffer for each link and contains up to three cells per link. The buffer can selectively collect:
•
•
•
•
The type of cells collected is defined in the RX Cell Type RAM (0x0100 and 0x0101) registers. A status bit and a
maskable IRQ alerts the software when a new cell is waiting for processing in a specific link. These are found in the
IRQ Link Status (0x0435-0x0444) and Enable (0x0445-0x0454) registers.
Software can directly access the cells in the RX buffer through a two-cell-wide access window using RX IMA ICP
Cell (0x0800 - 0x0BFF). This access window can be advanced, one cell at a time, by issuing a command to move
the internal pointer to the next cell. Since the window accesses two cells, the last processed cell can be accessed
at the window’s base address and the new cell at the base address plus 0x20.
The RX Cell Level FIFO Status (0x0106) register is used to read the level of any of the 16 RX ICP Cell buffers. A
’0’ in this register signifies that no new cell has been received. A ’2’ indicates the possibility that one or more cells
have been missed (overflow condition).
The cell in the last entry of the circular buffer is a temporary buffer (scratch pad). If, for example, the Cell FIFO level
is 2, it is constantly overwritten by any new valid incoming cell.
When the level is 0, the cell that is at the window’s base address is never overwritten as is kept for reference.
The RX Cell Buffer Increment Read Pointer (0x0105) register is used to advance the access window by 1 cell at
a time. Upon the command, the Buffer level is decreased by 1. When the level reaches 0, the window is not
advanced anymore.
all valid cells received on a RX TDM port
all valid ICP cells
all valid ICP cells which contain new information (as indicated by the SCCI field, valid only when the link is in
IMA mode)
no cells
Loss of IMA Frame (LIF) Synchronization
Filler Cell Handling
Stuff Cell Handling
Received ICP Cell Buffer
Zarlink Semiconductor Inc.
ZL30226/7/8
47
Data Sheet