Hello @nvko23
well, according to the schematics, SYS_INT is connected to multiple ICs, including PI4IOE5V6408, RX8130, AW9523, LM75 and INA226.
The required pull-up resistor (5.1k) is R10 - it's drawn near PI4IOE5V6408 on the CPU schematic.
Edit: I ran some tests - this is what I found:
Without any connections to Inputs 1 - 8 SYS_INT is high (as expected).
However if any input is asserted while powering up M5StampPLC SYS_INT goes low even though AW9523 interrupts are disabled during its initialization. See
here.
Adding _io_expander_b->resetIrq(); in the M5StapPLC library after disabling interrupts changes SYS_INT back to high.
My conclusion: AW9523 by default at power up has interrupts enabled and any interrupt sticks even when interrupts are disabled later on.
Thanks
Felix