ESP8266 Community Forum

INTERRUPT Gotcha : it would be useful to mention in the Interrupt docs that the interrupt pin requires a hardware pullup (or pulldown) resistor added for it to work (which some dev boards may already include, but breadboarded ESPs do not).

Another one, from my experience; do not use gpio3 (normally Rx) as an interrupt pin, even if you dont need the serial io; Interrupt does not seem to work consistently, even with a pullup, although the same pin works fine if polled.

If anybody's found out otherwise, I'd like to know, so I could re-edit my list of gotchas.

Hi Ardhuru,

A thought on your gpio03 interrupt inconsistency - floating inputs tend to float high, so when used for something, may have had a pulldown resistor added (typically 10K), in which case adding a similar value pullup would probably still leave the input in an indeterminate midway condition. Try using a 1K or 2K pullup and you might make the interrupt dependable.

I don't have time to waste unnecessarilly chasing shadows, so I'd be interested in having a peek at your Gotcha's list if that was possible?

Great point. Why didn't I think of that?!

I have indeed been using a pullup of 10k. I'll try lowering that today.

But how does that explain polling still working reliably, I wonder?