slow rising signal and edge triggered interrupt

[rohit269]

I have an input signal of 60 Hz (16.66 ms time period). The signal transition time(rise time/fall time) as measured on the oscilloscope is 1 ms.

Will the GPIO edge trigger interrupt service work for this signal? If not, what are the other ways to detect rising/falling time edge of this signal?

Thanks,

[yugguy]

The slow edge won't be a problem for triggering an edge interrupt as long as the the Vil/Vih thresholds are met. The problem may be multiple interrupts as the signal slowly transitions through the region between Vio x 0.75 and Vio x 0.25 (or vice-versa). Noise in the system and inside the ESP32 may contribute to spurious interrupts, as will AC line noise. The ESP32 IO pad likely has some hysteresis built-in which would help, though I don't see a spec for this.

Try directly connecting to the pin, if that doesn't work reliably you'll need to add an external schmitt trigger buffer.