3 t1 transmit synchronizer, T1 transmit synchronizer – Rainbow Electronics DS26519 User Manual

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DS26519 16-Port T1/E1/J1 Transceiver

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9.9.3 T1 Transmit Synchronizer

The DS26519 transmitter can identify the D4 or ESF frame boundary, as well as the CRC multiframe boundaries
within the incoming NRZ data stream at TSERn. The TFM (

TCR3

.2) control bit determines whether the transmit

synchronizer searches for the D4 or ESF multiframe. Additional control signals for the transmit synchronizer are
located in the

TSYNCC

TLS3

.0 (LOFD) is provided to indicate that a loss of frame

synchronization has occurred, and a real-time bit (LOF) which is set high when the synchronizer is searching for
frame/multiframe alignment. The LOFD bit can be enabled to cause an interrupt condition on

INTB.

Note that when the transmit synchronizer is used, the TSYNCn signal should be set as an output (TSIO = 1) and
the recovered frame-sync pulse will be output on this signal. The recovered CRC-4 multi-frame sync pulse will be
output if enabled with

TIOCR

.0 (TSM = 1).

Other key points concerning the E1 transmit synchronizer:

1) The Tx synchronizer is not operational when the transmit elastic store is enabled, including IBO modes.
2) The Tx synchronizer does not perform CRC-6 alignment verification (ESF mode) and does not verify

CRC-4 codewords.

The Tx synchronizer cannot search for the CAS multiframe.

Table 9-16

shows the registers related to the transmit

synchronizer.

Table 9-16. Registers Related to the Transmit Synchronizer

REGISTER

FRAMER 1

ADDRESSES

FUNCTION

Transmit Synchronizer Control Register
(

TSYNCC