á
PRELIMINARY
DS3 UNI FOR ATM
XRT7245
REV. 1.03
247
7.2.2.4
The Receive PLCP Processor will be disabled if the
XRT7245 DS3 UNI is configured to operate in the
“Direct Mapped ATM” Mode.
Direct-Mapped ATM Mode
7.2.2.5
Receive PLCP Processor-related
Interrupts
The Receive PLCP Processor will generate interrupts
upon the following conditions:
Change in OOF status
Change in LOF status
If one of these conditions occur, and if that particular
condition is enabled for interrupt generation, then
when the local
μ
C/
μ
P reads the UNI Interrupt Status
Register, as shown below; it should read “x1xxxxxxb”
(where the -b suffix denotes a binary expression, and
the “x” denotes a “don’t care” value).
At this point, the local μC/μP will have determined
that the Receive PLCP Processor block is the source
of the interrupt, and that the Interrupt Service Routine
should branch accordingly. In order to accomplish
this the local μP/μC should now read the Rx PLCP
Interrupt Status Register. The bit-format of the Rx
PLCP Interrupt Status register is presented below.
The bit format of the Rx PLCP Interrupt Status
Register indicates that only two (2) bit-fields, within
this register, are active. The role of each of these bit
fields follows.
F
IGURE
75. T
IMING
R
ELATIONSHIP
BETWEEN
THE
R
ECEIVE
PLCP POH B
YTE
S
ERIAL
O
UTPUT
P
ORT
PINS
—R
X
POH,
R
X
POHF
RAME
AND
R
X
POHC
LK
.
RxPOHFrame
RxPOHClk
RxPOH
t44
t45
t46
t43
UNI Interrupt Status Register (Address = 05h)
B
IT
7
B
IT
6
B
IT
5
B
IT
4
B
IT
3
B
IT
2
B
IT
1
B
IT
0
RxDS3
Interrupt
Status
RxPLCP
Interrupt
Status
RxCP
Interrupt
Status
Rx UTOPIA
Interrupt
Status
Tx UTOPIA
Interrupt
Status
TxCP
Interrupt
Status
TxDS3
Interrupt
Status
One Sec
Interrupt
Status
RO
RO
RO
RO
RO
RO
RO
RUR
Rx PLCP Interrupt Status Register (Address = 46h)
B
IT
7
B
IT
6
B
IT
5
B
IT
4
B
IT
3
B
IT
2
B
IT
1
B
IT
0
Unused
POOF Interrupt Status
RLOF Interrupt Status
RO
RO
RO
RO
RO
RO
RUR
RUR