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XRT94L33
3-CHANNEL DS3/E3/STS-1 TO STS-3/STM-1 MAPPER IC DATA SHEET
Rev.1.2.0.
139
1.4.1
GENERAL FLOW OF XRT94L33 ATM UNI/PPP DEVICE INTERRUPT SERVICING
When any of the conditions, presented in
Figure 6 occurs (if their Interrupt is enabled), then the XRT94L33
will generate an interrupt request to the
P/
C by asserting the active-low interrupt request output pin, INT*.
Shortly after the
P/C has detected the activated INT* signal, it will enter into the appropriate “user-supplied”
interrupt service routine. The first task, for the
P/C, while running this interrupt service routine, may be to
isolate the source of the interrupt request down to the device level (e.g., the XRT94L33 ATM UNI/PPP
device), if multiple peripheral devices exist in the user’s system.
However, once the “interrupting peripheral” device has been identified and determined to be the XRT94L33,
the next task for the
P/C is to identify the functional block within the XRT94L33 requested the interrupt.
Finally, the
P/C will need to proceed further and identify the exact condition(s) causing the interrupt to be
generated by the XRT94L33.
The procedure for servicing the “XRT94L33” Interrupts is best achieved by executing the following steps.
STEP 1 – DETERMINE THE FUNCTIONAL BLOCK(S) REQUESTING THE INTERRUPT
If the interrupting device turns out to be the XRT94L33 ATM UNI/PPP IC, then the
C/P must determine
which “functional block” requested the interrupt. Hence, upon reaching this state, one of the very first things
that the
C/P must do within the user supplied “XRT94L33” interrupt service routine, is to perform a read of
both of the following registers.
Operation Block Interrupt Status Register – Byte 1 (Address = 0x0112)
Operation Block Interrupt Status Register – Byte 0 (Address = 0x0113)
The bit-format of each of these registers is presented below.
Operation Block Interrupt Status Register – Byte 1 (Address Location = 0x0112)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Op Control
Block
Interrupt
Status
DS3/E3
Mapper
Block
Interrupt
Status
Unused
Receive
STS-1 TOH
Processor
Block
Interrupt
Status
Receive
STS-1 POH
Processor
Block
Interrupt
Status
DS3/E3
Framer
Block
Interrupt
Status
Receive
Line
Interface
Block
Interrupt
Status
Unused
R/O
0
Operation Block Interrupt Status Register – Byte 0 (Address Location = 0x0113)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Receive
ATM Cell
Processor
Block
Interrupt
Status
Receive
STS-3 TOH
Processor
Block
Interrupt
Status
Receive
SONET/
STS-3c
POH
Processor
Block
Interrupt
Status
Receive
PPP
Processor
Block
Interrupt
Status
Transmit
ATM Cell
Processor
Block
Interrupt
Status
Unused
Transmit
PPP
Processor
Block
Interrupt
Status
R/O
0