PCF INT Pin.

[boe666]

the INT is not connected to ESP32 on every PCF. Why ?

[admin]

because not enough gpio for you. PCF8574 already can work well without INT pin. if you MUST want use INT pin, you can connect with any ESP32 free GPIOs.
you question already posted in another topic. next time, suggest not post multi threads with same question.

[boe666]

after analyzing the pcb board I thought so too. However I checked and it seems to me that the GPIO12 pin (pin14) is free, it can be configured as an input and used normally in Arduino (tested). Maybe I'm wrong, but the diagram shows that it is not connected. One Pin for two PCF would be enough - the solution with interrupts allows for the certainty of reading each signal from the 16 digital inputs - without interruption there is a risk that some signal will be omitted.