
XRT84L38
387
REV. 1.0.1
Set the Receive Yellow Alarm State Change bit of the Alarm and Error Status Register to one indicating there
is a change in state of Yellow Alarm. This status indicator is valid until the Framer Interrupt Status Register is
read.
OCTAL T1/E1/J1 FRAMER
Reading this register clears the associated interrupt if Reset-Upon-Read is selected in Interrupt Control
Register (ICR). Otherwise, a write-to-clear operation by the microprocessor is required to reset these status
indicators.
The table below shows the Receive Yellow Alarm State Change status bits of the Alarm and Error Status
Register.
ALARM AND ERROR STATUS REGISTER (AESR) (INDIRECT ADDRESS = 0XNAH, 0X02H)
12.5.4
How to configure the framer to detect CAS Multi-frame Yellow Alarm
The Alarm indication logic within the Receive Framer block of the XRT84L38 framer monitors the incoming E1
frames for CAS Multi-frame Yellow Alarm condition. The CAS Multi-frame Yellow Alarm is detected and
declared according to the following procedure:
1.
Monitor the occurrence of CAS Multi-frame Yellow Alarm pattern over a 4 ms interval. An MYEL valid flag
will be posted on the interval when CAS Multi-frame Yellow Alarm pattern occurred during the interval.
2.
Each interval with a valid MYEL flag increments a flag counter which declares MYEL alarm when 80 valid
intervals have been accumulated.
3.
An interval without valid MYEL flag decrements the flag counter. The MYEL alarm is removed when the
counter reaches zero.
If CAS Multi-frame Yellow Alarm condition is present in the incoming E1 frame, the XRT84L38 framer can
generate a Receive CAS Multi-frame Yellow Alarm State Change interrupt associated with the setting of
Receive CAS Multi-frame Yellow Alarm State Change bit of the Alarm and Error Status Register to one.
To enable the Receive CAS Multi-frame Yellow Alarm State Change interrupt, the Receive CAS Multi-frame
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 CAS Multi-frame 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)
B
IT
N
UMBER
B
IT
N
AME
B
IT
T
YPE
B
IT
D
ESCRIPTION
0
Receive Yellow
Alarm State
Change
RUR /
WC
0 - There is no change of Yellow Alarm state in the incoming E1 payload
data.
1 - There is change of Yellow Alarm state in the incoming E1 payload data.
B
IT
N
UMBER
B
IT
N
AME
B
IT
T
YPE
B
IT
D
ESCRIPTION
5
Receive CAS
Multi-frame Yellow
Alarm State
Change Interrupt
Enable
R/W
0 - The Receive CAS Multi-frame Yellow Alarm State Change interrupt is
disabled. Any state change of Receive CAS Multi-frame Yellow Alarm will
not generate an interrupt.
1 - The Receive CAS Multi-frame Yellow Alarm State Change interrupt is
enabled. Any state change of Receive CAS Multi-frame Yellow Alarm will
generate an interrupt.