NRND

TP3404

SNOS703 – DECEMBER 2004

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Table 6. Status Register Functions

Byte 2

Indication

7

6

5

4

3

2

1

0

0

0

Line 3: deactivated

0

1

Line 3: line signal present but not in sync

1

0

1

1

Line 3: activated, no bipolar violation

0

0

Line 2: deactivated

0

1

Line 2: line signal present but not in sync

1

0

1

1

Line 2: activated, no bipolar violation

0

0

Line 1: deactivated

0

1

Line 1: line signal present but not in sync

1

0

1

1

Line 1: activated, no bipolar violation

0

0

Line 0: deactivated

0

1

Line 0: line signal present but not in sync

1

0

1

1

Line 0: activated, no bipolar violation

(1)

Bipolar Violation does not cause an Interrupt.

STATUS REGISTER

Status information for all 4 channels may be read from the common Status Register by addressing location X

′FF.

2 bits per line are coded as shown in Table 6. A change in the status of 1 or more lines is indicated by the INT

pin being pulled low, provided bit 2 of the corresponding control register is set to “ONE” to enable the interrupt for

that line.

BIPOLAR VIOLATION DETECTOR

On an activated line, whenever a line error is received there will be a violation of the AMI coding rule. This is

reported by setting the code 10 for that line. The violation indication is cleared to 11 after a read of the Status

Register.

As an example of the interpretation of the Status Register contents, if the byte 2 read back from the Status

Register =00111001 (=X

′39), this indicates the following status of the 4 lines: line 3 is deactivated; line 2 is in

sync with no error since the last read cycle; line 1 is in sync but there has been 1 or more errors since the last

read cycle of the Status Register; line 0 is receiving a line signal but the line transmission is not synchronized.

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