Flow meter using Wemos Mini - ISR not in IRAM! I'm trying to use a flow meter with Wemos Mini.
Most tutorials are using Arduino boards ( which code and HW work OK ), but since I want this device to send alerts over the internet when abnormal usage/leakage is detected, I want to use Wemos Mini using How to Use Water Flow Sensor - Arduino Tutorial. On top of if will add my code for notifications using Telegram.

BUT - after uploading the original code (before adding Telegram changes ), an error occurs during code run : ISR not in IRAM!

I tried to change Pin - but still getting this error,
This happens because of conflicts between Serial and external interrupts
Put ICACHE_RAM_ATTR before your interrupt function, like this  ICACHE_RAM_ATTR void ISR()