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I/O 40 Extender capable of interrupt



Are the IO’s on the extender via I2C interrupt capable? I couldnt find it in the documentation.



Hmm, two answers, all pins are interrupt capable. But I suspect that the interrupt pin from the expander isn’t fed to the EMX/Cobra.

How this could/should work: The expander fires an interrupt on the Cobra telling it that one of the pins on the expander has changed. It is then up to the Cobra to figure out which pin changed.

Thus, you can’t create an InterruptPin class for the pins on the expander. But using the interrupt provided by the chip on the expander you dont have to continually read the expander to see when something changes…



this is the way most i2c port expanders work. We use them a lot. The most of them have got an output that will go low if one of the inputs changes.

Like Errol said, you will need to connect that output of your expander to an interrupt capable input of your processor. Then you will only need to re read the inputs of your expander when the interruptoccurs.




This is already done by a community member. Look here: