Datasheet

Data Sheet AD7877
Rev. D | Page 31 of 44
If the
ALERT
source is a GPIO, then masking out the interrupt
by clearing the corresponding ALEN bit to 0 or removing the
source of the interrupt on the GPIO pin causes
ALERT
to go
high again.
If the
ALERT
source is an out-of-limit measurement, writing a
0 to the corresponding status bit in the alert status/enable
register causes
ALERT
to go high. However, the status bit is set
to 1 again on the next measurement cycle, if the measurement
remains out of limit. The
ALERT
source can also be masked by
clearing the relevant bit in the alert status/enable register to 0.
Table 12. GPIO Configuration
EN DIR POL ALEN Data Bit Pin Voltage
ALERT
0 X X X X X X
1 0 0 0 0 1
1
1
1 0 0 0 1 0
1
1
1 0 0 1 0 1
1
1
1
0
0
1
1
0
1
1
1 0 1 0 0 0
1
1
1 0 1 0 1 1
1
1
1 0 1 1 0 0
1
1
1 0 1 1 1 1
1
1
1
1
0
0
1
2
0
1
1 1 0 0 0
2
1 1
1 1 0 1 1
2
0 0
1 1 0 1 0
2
1 1
1 1 1 0 0
2
0 1
1 1 1 0 1
2
1 1
1
1
1
1
0
2
0
1
1 1 1 1 1
2
1 0
1
A change in the data register causes a change in the output voltage on the pin.
2
A change in input voltage on the pin causes a change in the data register bit.