
XRT84L38
348
OCTAL T1/E1/J1 FRAMER
REV. 1.0.1
The table below shows the Receive Red Alarm State status bits of the Alarm and Error Status Register.
ALARM AND ERROR STATUS REGISTER (AESR) (INDIRECT ADDRESS = 0XNAH, 0X02H)
10.6.3
How to configure the framer to detect Yellow Alarm
The Alarm indication logic within the Receive Framer block of the XRT84L38 framer monitors the incoming
DS1 frames for Yellow Alarm condition. The yellow alarm is detected and declared according to the following
procedure:
1.
Monitor the occurrence of Yellow Alarm pattern over a 6 ms interval. A YEL valid flag will be posted on the
interval when Yellow Alarm pattern occurred during the interval.
2.
Each interval with a valid YEL flag increments a flag counter which declares YEL alarm when 80 valid
intervals have been accumulated.
3.
An interval without valid YEL flag decrements the flag counter. The YEL alarm is removed when the
counter reaches zero.
If Yellow Alarm condition is present in the incoming DS1 frame, the XRT84L38 framer can generate a Receive
Yellow Alarm State Change interrupt associated with the setting of Receive Yellow Alarm State Change bit of
the Alarm and Error Status Register to one.
To enable the Receive Yellow Alarm State Change interrupt, the Receive Yellow Alarm State Change Interrupt
Enable bit of the Alarm and Error Interrupt Enable Register (AEIER) has to be set to one. In addition, the Alarm
and Error Interrupt Enable bit of the Block Interrupt Enable Register (BIER) needs to be one.
The table below shows configurations of the Receive Yellow Alarm State Change Interrupt Enable bit of the
Alarm and Error Interrupt Enable Register (AEIER).
ALARM AND ERROR INTERRUPT ENABLE REGISTER (AEIER) (INDIRECT ADDRESS = 0XNAH, 0X03H)
The table below shows configurations of the Alarm and Error Interrupt Enable bit of the Block Interrupt Enable
Register.
BLOCK INTERRUPT ENABLE REGISTER (BIER) (INDIRECT ADDRESS = 0XNAH, 0X01H)
When these interrupt enable bits are set and Yellow Alarm is present in the incoming DS1 frame, the
XRT84L38 framer will declare Yellow Alarm by doing the following:
B
IT
N
UMBER
B
IT
N
AME
B
IT
T
YPE
B
IT
D
ESCRIPTION
7
Receive Red Alarm
State
R
0 - There is no Red Alarm condition detected in the incoming DS1 payload
data.
1 - There is Red Alarm condition detected in the incoming DS1 payload
data.
B
IT
N
UMBER
B
IT
N
AME
B
IT
T
YPE
B
IT
D
ESCRIPTION
0
Receive Yellow
Alarm State
Change Interrupt
Enable
R/W
0 - The Receive Yellow Alarm State Change interrupt is disabled. Any state
change of Receive Yellow Alarm will not generate an interrupt.
1 - The Receive Yellow Alarm State Change interrupt is enabled. Any state
change of Receive Yellow Alarm will generate an interrupt.
B
IT
N
UMBER
B
IT
N
AME
B
IT
T
YPE
B
IT
D
ESCRIPTION
1
Alarm and Error
Interrupt Enable
R/W
0 - Every interrupt generated by the Alarm and Error Interrupt Status Reg-
ister (AEISR) is disabled.
1 - Every interrupt generated by the Alarm and Error Interrupt Status Reg-
ister (AEISR) is enabled.