MT9072AB datasheet(53/275 Pages) ZARLINK

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MT9072

Data Sheet

Zarlink Semiconductor Inc.

achieve CRC-4 multiframe alignment by the end of a predefined period, the distant end is considered to be a

non-CRC-4 interface. When the distant end is a non-CRC-4 interface, the near end automatically suspends receive

CRC-4 functions, continues to transmit CRC-4 data to the distant end with its E-bits set to zero, and provides a

status indication. Naturally, if the distant end initially achieves CRC-4 synchronization, CRC-4 processing will be

carried out by both ends. This feature is selected when control bit AUTC (control register address Y00) is set to

zero.

5.2.4.1

Notes for Synchronization State Diagram (Figure 7)

1. The basic frame alignment, signaling multiframe alignment, and CRC-4 multiframe alignment functions operate

in parallel and are independent.

2. The receive channel associated signaling bits and signaling multiframe alignment bit will be frozen when multi-

frame alignment is lost.

3. Manual re-framing of the receive basic frame alignment and signaling multiframe alignment functions can be

performed at any time.

4. The transmit RAI bit will be one until basic frame alignment is established, then it will be zero.

5. E-bits can be optionally set to zero until the equipment interworking relationship is established. When this has

been determined one of the following will take place:

a) CRC-to-non-CRC operation - E-bits = 0,

b) CRC-to-CRC operation - E-bits as per G.704 and I.431.

6. All manual re-frames and new basic frame alignment searches start after the current frame alignment signal

position.

7. After basic frame alignment has been achieved, loss of frame alignment will occur any time three consecutive

incorrect basic frame alignment signals are received. Loss of basic frame alignment will reset the complete

framing algorithm.

8. When CRC-4 multiframe alignment has been achieved, the primary basic frame alignment and resulting multi-

frame alignment will be adjusted to the basic frame alignment determined during CRC-4 synchronization. There-

fore, the primary basic frame alignment will not be updated during the CRC-4 multiframe alignment search, but

will be updated when the CRC-4 multiframe alignment search is complete.

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