XRT86VL34 datasheet(22/156 Pages) EXAR

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XRT86VL34

QUAD T1/E1/J1 FRAMER/LIU COMBO - T1 REGISTER DESCRIPTION

REV. V1.2.0

5-4

YEL[1:0]

R/W

Yellow Alarm (RAI) Duration and Format

The exact function of these bits depends on whether or not the one-second yellow

alarm rule is enforced. (Bit 7 of this register). The decoding of these bits are

explained in Table 6 and Table 7 below.

TABLE 5: ALARM GENERATION REGISTER (AGR)

HEX ADDRESS: 0Xn108

BIT

FUNCTION

TYPE DEFAULT

DESCRIPTION-OPERATION

TABLE 6: YELLOW ALARM DURATION AND FORMAT WHEN ONE SECOND RULE IS NOT

ENFORCED

YEL[1:0]

YELLOW ALARM DURATION AND FORMAT

Disable the transmission of yellow alarm

SF or N mode:

RAI is transmitted as bit 2 = 0 (second MSB) in all DS0 data chan-

nel.

T1DM mode:

RAI is transmitted as Y-bit = 0 (6th bit in the SYNC byte).

ESF mode:

1. If YEL[0] bit is set ’high’ for a duration shorter or equal to the

time

required

transmit

255

patterns

1111_1111_0000_0000 on the 4-kbit/s data link bits (M1-

M12),

RAI

transmitted

for

255

patterns.of

1111_1111_0000_0000 (approximately 1 second)

2. If YEL[0] bit is set ’high’ for a duration longer than the time

required to transmit 255 patterns of 1111_1111_0000_0000

on the 4-kbit/s data link bits (M1-M12), RAI transmission

continues until YEL[0] bit is set ’low’.

3. If

YEL[0]

bit

forms

another

pulse

during

the

RAI

transmission, it resets the pattern counter and extends the

RAI

duration

for

another

255

patterns

1111_1111_0000_0000. (approximately 1 second)

SF mode:

RAI is transmitted as a “1” in the Fs bit of frame 12 (This is RAI for

J1 SF standard).

T1DM mode:

RAI is transmitted as Y-bit = 0 (6th bit in the SYNC byte).

ESF mode:

RAI is controlled by the duration of YEL[1] bit. This allows continu-

ous RAI of any length.

SF, N, and T1DM mode:

RAI format is the same as described above when YEL[1:0] is set

to’01’.

ESF mode:

RAI duration is the same as described above when YEL[1:0] is set

to’01’, except that format of RAI is transmitted as 255 patterns of

1111_1111_1111_1111 (sixteen ones) on the 4kbits/s data link bits

instead of 255 patterns of 1111_1111_0000_0000.

NOTE:

255 patterns of 1111_1111_1111_111 is the J1 ESF RAI

standard)

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