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2016-01-0019

PT0549-3

02/15/16

13

PI4IOE5V9539

16-bit I

low power I/O port with interrupt and reset

iii.

Interrupt output

The open-drain interrupt output is activated when one of the port pins changes state and the pin is configured as an input.

The interrupt is deactivated when the input returns to its previous state or the Input Port register is read. A pin configured as

an output cannot cause an interrupt. Since each 8-bit port is read independently, the interrupt caused by Port 0 will not be cleared

by a read of Port 1 or the other way around.

Note: Changing an I/O from an output to an input may cause a false interrupt to occur if the state of the pin does not match

the contents of the Input Port register.

Figure 9: Read Input port register

Note: Transfer of data can be stopped at any moment by a STOP condition. When this occurs, data present at the latest acknowledge phase is valid (output

mode). It is assumed that the command byte has previously been set to ‘00’ (read Input Port register).