ESP8266 Community Forum

Hi;
just some information for the community:
I had endless problems with using interrupts and I was banging my had reg. what I am doing wrong (soft- and hardware wise).
I exchanged powersupplies, adding capacitors to the power supply, grounded the ESP, shielded cables.... nothing helped - my interrupts fired randomly without trigger.
The odd thing, which finally helped me to find the root cause:
When I ran it connected to the PC (via USB), everything was cool.
When I used it offline insitu, it misbehaved.

The solution: A ferrite core wrapping around the power cable!
(The ferrite core from the USB cable helped - even when it was not plugged to the PC!)
Now the noise is gone and I can use interrupts.

I thought this might be good information for other as well.

Heiner

Awesome find!

Yes, there are other issues too such as improper power-up followed by high power consumption sometimes when power supply is not properly regulated and noise free. Also, messing with GPIO15 (which is unfortunately a part of HSPI as well) creates issues with booting if power supply is not of good quality.
So if these issues are seen too often, especially when breadboarding, then power supply or GPIO15 is the cause.

it is more likely your power supply that needs the ferrite core, not the ESP.
The picture you present says that ESP is running well on a stable, filtered power supply.
But when presented with unhealthy influence (noise) via the power supply the ESP misbehaves.
That holds most likely true for a huge percentage of microprocessors....
Usually they proof to be susceptible to "noise" on the interrupt line, too.
To sum it up: a good clean (emc proof) design can't be beaten ...