DS2141A Ver la hoja de datos (PDF) - Maxim Integrated

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DS2141A

T1 Controller

Maxim Integrated 

SR1: STATUS REGISTER 1 (20h)

(MSB)

LUP

LDN

LOTC

SLIP

RBL

RYEL

RCL

DS2141A

(LSB)

RLOS

SYMBOL POSITION NAME AND DESCRIPTION

LUP

SR1.7

Loop Up Code Detected. Set when the repeating …00001…

loop up code is being received.

LDN

SR1.6

Loop Down Code Detected. Set when the repeating …001…

loop down code is being received.

LOTC

SR1.5

Loss of Transmit Clock. Set when the TCLK pin has not

transitioned for one channel time (or 5.2 µs). Will force pin-34

high if enabled via CCR1.6. Based on RCLK.

SLIP

SR1.4

Elastic Store Slip Occurrence. Set when the elastic store has

either repeated or deleted a frame of data.

RBL

SR1.3

Receive Blue Alarm. Set when an all 1's code is received at

RPOS and RNEG.

RYEL

SR1.2

Receive Yellow Alarm. Set when a yellow alarm is received at

RPOS and RNEG.

RCL

SR1.1

Receive Carrier Loss. Set when 192 consecutive 0s have been

detected at RPOS and RNEG.

RLOS

SR1.0

Receive Loss of Sync. Set when the device is not synchronized

to the receive T1 stream.

LOOP UP/DOWN CODE DETECTION

Bits SR1.7 and SR1.6 will indicate when either the standard “loop up” or “loop down” codes are being

received by the DS2141A. When a loop up code has been received for 5 seconds, the CPE is expected to

loop the recovered data (without correcting BPVs) back to the source. The loop down code indicates that

the loopback should be discontinued. See the AT&T publication TR 62411 for more details. The

DS2141A will detect the loop up/down codes in both framed and unframed circumstances with bit error

rates as high as 10-2. The loop code detector has a nominal integration period of 48 ms. Hence, after about

48 ms of receiving either code, the proper status bit will be set to a 1. After this initial indication, it is

recommended that the software poll the DS2141A every 100 ms to 500 ms until five seconds have

elapsed to insure that the code is continuously present. Once five seconds have passed, the line interface

should be taken into or out of loopback.

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