3-10
Signal Descriptions
3.2.6 Interrupt Signals
describes the Interrupt Signals group.
Table 3.7
Interrupt Signals
Name
1
Bump
Type
Strength
Description
INTA/
F4
O
16 mA
PCI
Interrupt Function A. This signal, when asserted LOW,
indicates an interrupting condition in SCSI Function A and
that service is required from the host CPU. The output drive
of this pin is open drain. If the SCSI Function B interrupt is
rerouted at power-up using the INTA/ enable sense resistor
(pull-up on MAD[4]), this signal indicates that an interrupting
condition has occurred in either the SCSI Function A or
SCSI Function B. This interrupt pin is disabled if INT_DIR is
driven LOW.
INTB/
F2
O
16 mA
PCI
Interrupt Function B. This signal, when asserted LOW,
indicates an interrupting condition has occurred in the SCSI
Function B and that service is required from the host CPU.
The output drive of this pin is open drain. This interrupt can
be rerouted to INTA/ at power-up using the INTA/ enable
sense resistor (pull-up on MAD[4]). This causes the
LSI53C896 to program the SCSI Function B PCI Interrupt
Pin register (
) to 0x01. This interrupt pin is disabled if
INT_DIR is driven LOW.
ALT_INTA/
F1
O
16 mA
PCI
Alt Interrupt Function A. When asserted LOW, it indicates
an interrupting condition has occurred in SCSI Function A.
The output drive of this pin is open drain. If the SCSI
Function B interrupt was rerouted at power-up using the
INTA/ enable sense resistor (pull-up on MAD[4]), this signal
indicates that an interrupting condition has occurred in
either the SCSI Function A or SCSI Function B.
ALT_INTB/
G3
O
16 mA
PCI
Alt Interrupt Function B. When asserted LOW, indicates
an interrupting condition has occurred in SCSI Function B.
The output drive of this pin is open drain. This interrupt can
be rerouted to INTA/ at power-up using the INTA/ enable
sense resistor (pull-up on MAD[4]). This will cause the
LSI53C896 to program the Function B PCI Interrupt Pin
register (
) to 0x01.
INT_DIR
G2
I
N/A
Interrupt Direction. This input signal indicates whether
internally generated interrupts will be presented on INTA/
and INTB/. If INT_DIR is HIGH, internal interrupts will be
generated on both the INTx/ pins and the ALT_INTx pin. If
INT_DIR is LOW, the internal interrupts will be generated
only on the ALT_INTx/ pin. This pin has a static pull-up.
1. See Register 0x4D,
in
for additional information
on these signals.
*
Summary of Contents for LSI53C896
Page 6: ...vi Preface...
Page 16: ...xvi Contents...
Page 88: ...2 62 Functional Description...
Page 112: ...3 24 Signal Descriptions...
Page 306: ...6 38 Specifications This page intentionally left blank...
Page 310: ...6 42 Specifications This page intentionally left blank...
Page 338: ...6 70 Specifications Figure 6 40 LSI53C896 329 BGA Bottom View...
Page 340: ...6 72 Specifications...
Page 346: ...A 6 Register Summary...
Page 362: ...IX 12 Index...