What is "HIGH" on an ESP32

I have been climbing the learning curve on the ESP32, and I keep finding out new things that seem strange. I built an EXT1 interrupt that triggers when a pin goes high. Now 3.3 v. logic specifies that HIGH is 2 v. or above, but I find my interrupt triggers at exactly 1.565, or half the supply voltage. Do I have a freak chip, or is this the ESP32 definition of HIGH?



Manufacturers will specify a minimum voltage that is guaranteed to be read as a high (anything above that will be a HIGH for sure too), and a maximum voltage that is guaranteed to be read as a low (anything below that would also be a LOW). Between those values, there is no firm spec. On many parts it flips at around the middle, but there may be some hysteresis, it may depend how fast the signal is changing, etc. Manufacturer makes no guarantees.