
XRT84L38
168
OCTAL T1/E1/J1 FRAMER
REV. 1.0.1
N
OTE
:
Setting this bit-field to "1" does not enable all of the interrupts within the Framer. A given interrupt must also be
enabled at the block and source-level before it is enabled for interrupt generation.
1.7.1.2
Configuring the Interrupt Status Bits within a given Framer to be Reset-upon-Read or
Write-to-Clear.
The XRT84L38 Source-Level Interrupt Status Register bits can be configured to be either Reset-upon-Read or
Write-to-Clear. If the user configures the Interrupt Status Registers to be Reset-upon-Read, then when the
μ
P/
μ
C is reading the interrupt status register, the following happens:
1.
The contents of the Source-Level Interrupt Status Register automatically is reset to “0x00" following the
read operation.
2.
The Interrupt Request Output pin (INT) automatically toggles false, or "High", upon reading the Interrupt
Status Register containing the last activated interrupt status bit.
If the user configures the Interrupt Status Registers to be Write-to-Clear, then when the
μ
P/
μ
C is reading the
interrupt status register, the following happens.
1.
The contents of the Source-Level Interrupt Status Register is not cleared to "0x00" following the read oper-
ation. The
μ
P/
μ
C has to write 0x00 to the interrupt status register in order to reset the contents of the reg-
ister to 0x00.
2.
Reading the Interrupt Status Register, which contains the activated bit(s) does not cause the Interrupt
Request Output pin (INT) to toggle false. The Interrupt Request Output pin does not toggle false until the
μ
P/
μ
C has written 0x00 into this register. The Interrupt Service Routine must include this write operation.
The Interrupt Status Register associated with a given framer can be configured to be either Reset-upon-Read
or Write-to-Clear by writing the appropriate value into Bit 2 within the Interrupt Control Register (see
Table 29
).
1.7.1.3
Automatic Reset of Interrupt Enable Bits
Occasionally, the user's system which includes the Framer, may experience a fault condition, such that a
Framer Interrupt Condition continuously exists. If this particular interrupt has been enabled, then the Framer
will generate an interrupt request to the
μ
P/
μ
C. Afterwards, the
μ
P/
μ
C attempts to service this interrupt by
reading the appropriate Block-level and Source-Level Interrupt Status Register. Additionally, the local
μ
P/
μ
C
attempts to perform some system-related tasks in order to try to resolve these conditions causing the interrupt.
After the local
μ
C/
μ
P has attempted all of these things, the Framer negates the INT output pin. However,
because this system fault still remains, the condition causing the Framer to issue this interrupt also exists.
Consequently, the Framer generates another interrupt request which forces the
μ
P/
μ
C to once again attempt
to service this interrupt. This results in the local
μ
P/
μ
C being tied up in a continuous cycle of executing this one
T
ABLE
29: I
NTERRUPT
C
ONTROL
R
EGISTER
R
EGISTER
26 I
NTERRUPT
C
ONTROL
R
EGISTER
(ICR) H
EX
A
DDRESS
: 0
X
n0, 0
X
1A
B
IT
M
ODE
F
UNCTION
T
YPE
D
EFAULT
D
ESCRIPTION
-O
PERATION
7-3
Unused
RO
0
2
INT_WC_RUR
R/W
0
Interrupt Write-to-Clear or Reset-upon-Read Select
Configures Interrupt Status bits to either RUR or Write-to-Clear
0=Interrupt Status bit RUR
1=Interrupt Status bit Write-to-Clear
1
ENBCLR
R/W
0
Interrupt Enable Auto Clear
0=Interrupt Enable bits are not cleared after status reading
1=Interrupt Enable bits are cleared after status reading
0
INTRUP_ENB
R/W
0
Interrupt Enable for Framer_n
Enables Framer n for Interrupt Generation.
0 = Disables corresponding framer block for Interrupt Generation
1 = Enables corresponding framer block for Interrupt Generation