TCA6416: How to use INT Pin

The interrupt pin allows you to detect changes at the inputs without having to regularly reading the expander registers. This might or might not be useful in your application.

Hi Gareth,

Clemens is correct in his explanation. 

In a practical case, we usually see customers utilize the interrupt pin as a feedback output to the MCU. For example, an input on the TCA6416 changes states. This flags the interrupt pin to transition from a high to low logic level. This interrupt pin has some connection to the MCU. The MCU sees the falling edge on the /INT pin, and then proceeds to do some calculation / reading data from the IO expander to detect the input that changed state. 

I.e. a push button is pressed, P0 changes state, /INT goes LOW, MCU takes in the interrupt and proceeds to read data from the IO expander. 

In another case where an IO expander does not have an /INT pin, a state may change on the IO expander input, but the MCU would not realize it. Thus the MCU would have to constantly poll the IO expander to check periodically for data changes. 

Regards,

Tyler