MCP23S17 Microchip Technology, MCP23S17 Datasheet - Page 25

• Manufacturer Part Number: MCP23S17
• Description: 16-Bit I/O Expander with Serial Interface
• Manufacturer: Microchip Technology

1.7.5
There are two possible configurations that cause
interrupts (configured via INTCON):
1.
2.
See
interrupt operations.
FIGURE 1-6:
© 2007 Microchip Technology Inc.
Port value
is captured
into INTCAP
GPx
Pins configured for interrupt-on-pin change
will cause an interrupt to occur if a pin changes
to the opposite state. The default state is reset
after an interrupt occurs and after clearing the
interrupt condition (i.e., after reading GPIO or
INTCAP). For example, an interrupt occurs by
an input changing from ‘1’ to ‘0’. The new initial
state for the pin is a logic 0 after the interrupt is
cleared.
Pins configured for interrupt-on-change from
register value will cause an interrupt to occur if
the corresponding input pin differs from the
register bit. The interrupt condition will remain as
long as the condition exists, regardless if the
INTCAP or GPIO is read.
Figure 1-6
INT
INTERRUPT CONDITIONS
and
ACTIVE
Figure 1-7
INTERRUPT-ON-PIN
CHANGE
Read GPIO
or INTCAP
for more information on
Port value
is captured
into INTCAP
ACTIVE
MCP23017/MCP23S17
FIGURE 1-7:
GP:
GP2
Pin
INT
Pin
Port value
is captured
into INTCAP
7
X
6
X
ACTIVE
DEFVAL REGISTER
5
X
INTERRUPT-ON-CHANGE
FROM REGISTER
DEFAULT
4
X
(INT clears only if interrupt
condition does not exist.)
3
X
Read GPIU
or INTCAP
ACTIVE
2
0
DS21952B-page 25
1
X
0
X